2 Ways Lithium KILLS Your Alternator (and how to prevent it)

In this week's video, I answer the question "Is my alternator safe with LiFePO4 batteries?" The answer is... it isn't-unless you take precautions.
In this video, I refer to a thermal switch I bought. It was a 10-amp, normally-closed thermal switch. I chose one rated for shutdown at 110-degrees C. That temperature is something you should choose yourself, but I think that is a good number for a thermo-switch mounted inside the alternator case.
In preparing for this video I searched eBay again and found a better choice. This is the same basic thing, but this one is rated for 16a. That would be more then plenty for any alternator I've seen. Also, it's CHEAPER!
www.ebay.com/i...
A commenter brought up a concern (thanks Apollo). He thought that the thermal switch might suffer from the back emf of the coil being disconnected when things overheat. He might be right though I have seen this done in motors before. Either way a simple "flyback diode" (Google it) might give extra protection and is cheap and easy to install.
Another thing that I wish I had talked about in this video was engine room ventilation. It seems basic but keep it cooler around your alternator and your alternator will run cooler!
Well as I say the description section is how I reserve the right to get smarter.
If you would like to learn more about the BankManager or order one, check out:
www.emilyandcl...
Here is a link to the video where I talk about engine belt upgrade • Boat DIESEL ENGINE Hac...
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[@bearchow1929]

I'm a highly accomplished electronic engineer in several things including power management systems and devices used in alternators and battery management systems. I passed by your video thinking "what is this non sense". I was quite surprised to find that you are quite technically correct in this video. Excellent job.

[@pieterbezuidenhout2741]

It's the years experience that sometimes counts more than the Qualifications 😁.

[@davelee7572]

why not just run a 4x4 relay dual battery VSR? if the bms cuts out the lead acid battery will still be there.

[@EmilyAndClark]

Because the lithium gets mischarged by the alternator.

[@davelee7572]

@@EmilyAndClark mischarged how? "Lithium Ion batteries are charged with an absorption voltage of 14.25 V"

[@EmilyAndClark]

They shouldn't be. I suggest you read Conrad's writeup linked to the bottom of this. www.emilyandclarksadventure.com/bbms

[@mikehill3764]

The service manager at the marine mechanic facility I use just talked me out of using a lifepo4 battery for my starting motor. He was worried about how the charging system would be affected on my mercury pro xs. Told me to stick with agm and that’s exactly what I plan to do. Nice video. Very informative.

[@EmilyAndClark]

I agree. Use lead for starting. If you want to add more battery you can add li in parallel with a BankManager

[@jgatkinson744]

I remember when alternators first come out I was working for the Ford company on the coast of Mississippi. They sent us to auto school in New Orleans and they explain the function of the alternator they were going to replace the generator on cars and they replace them were the last cars, we had that had generators 1960 alternators took their place the fields turned inside the armature right reversed to what a generator did and you had to have 1 1/2 volt to excite them to make them work. If you had a dead battery you could push that car all day long and it would never generate any power that was a long time ago we have come along way now with electronics . Grate job Clark as always

[@EmilyAndClark]

Thanks

[@TreDeuce-qw3kv]

And people mistakenly think batteries and charging systems are simple and don't understand why I think they aren't. This post and the following comments/discussion support my contention. I rarely read comments, but I took probably an hour or more to go through these. Very informative and time well spent....👍👍

[@EmilyAndClark]

Yes Everything is simple until you understand it.

[@CruisingMaya]

Thanks for the great breakdown, Clark! I'm a marine electrician and have hesitated to do lithium installs on my customers' boats because of the off chance that a BMS opens the circuit, frying the alternator and everything else. I REALLY like that the lead battery is there as a guardian.... and now with ways to thermally protect even internally regulated alternators I'm even more excited. I'm currently cruising, but will be back to work in a few months. I look forward to the next video and the possibility of installing a bank manager. Thanks again for the great video and sharing your knowledge!

[@nordic5490]

No chance that a soft start 50A BMS can fry the alternator when a 90A compressor, or a 200A winch with ugly back emf, doesnt. The starter battery has very low impedence and is the voltage clamp, in much the same way as a giant zener diode

[@EmilyAndClark]

@maya. Have you gotten back yet? Did you find an opportunity to do a BankManager install?

[@darrellobrien4416]

would a flyback diode work with the lithium battery BMS shutting down?

[@EmilyAndClark]

@@darrellobrien4416 nope. It's not a reversed colapsing field. It's just the alternator making full power. Forward and too strong for a diode anyway.

[@CruisingMaya]

@EmilyAndClark almost had a customer convinced to get a lithium bank and keep the existing lead acid. They didn't go for it though...

[@michaelm6682]

The way the author of this channel explains and teaches reminds me of my enthusiasm for science as a youngster in class (late 70s-early 80s). I’ve had deafness since birth, and what little I could understand verbally was supplemented by visuals in the classroom. The author has many of the qualities of those teachers I admire and I appreciate that very much. Thank you so much. As an adult, with my deafness, KZbin, with its closed captioning, has made the educational aspects much more accessible thank goodness. With the help of YT, I’m attempting to design & build a 100ah lipo battery system for my truck with limited space. I’ve purchased a Renogy 12V 30A DC to DC Charger with MPPT, On-Board Battery Charger. At the moment, after learning from this video, It’s clear that I need a system that is plug and play. I don’t have the capacity to understand all the science at play here. I use my truck daily as part of my job doing outreach and reliability and safety is my utmost concern. As well as affordability, which is why I’m trying to design and build it myself. I just wish there was a complete system I could install myself with more confidence in those goals. Any suggestions? Thanks for “hearing” me explain my situation in advance. Kind regards.

[@EmilyAndClark]

You might find this useful. www.emilyandclarksadventure.com/bbms

[@Nerd3927]

Excellent! I use a DC DC converter from 12v to 24v since my house battery is 24v, but I never thought of a thermal switch as a protection. Very simple and cheap :-)

[@douglasrobbie9998]

Great video, valuable info with minor amount of self-promotion. I see so many people switching to the external regulator alternators at great cost.

[@herberthahn6964]

Clark, your tutorials are always full of great information. Emily help with mad scientist look. We all know he isn't mad.

[@MrZeissOne]

Thanks Clark. I'm finding you far more straightforward and informative than the battery manufacturers. Q: If I go either the dc-dc or Battery Bank route, d o I need to install a monitor or alarm/fuseto let me know if it fails? Or, is my first indication smoked alt diodes. I sent an inquiry to LiTime, asking if they are recommending any sort of dc regulator. So far, no response. And I'm finding lithium battery ads pushing their products as "drop in replacements" for lead acid batteries. The alternator is a convenient back-up for cloudy days, so I would really like to retain it as a charging source. However, I've just done an alternator replacement. It was not fun, easy, or cheap, and I'm not looking forward to doing it again soon. Thanks again for this video. It's a valuable service for any of us who go lithium! 4:56

[@EmilyAndClark]

Li is nowhere close to a drop in replacement for Pb. Even the li charger controllers available today don't charge it right for a long life. To keep your alternator cool the best solution is an external regulator with a temperature sensor. I've always used Balmar. People I respect like Sterling. BankManager and some lead will keep your alternator's diodes safe and charge your Li property for a long life. (So there's my commercial. ) www.emilyandclarksadventure.com/bbms I'm not a fan of DCDC chargers. I think I go into it in the FAQs in the link above

[@Tron-Jockey]

For an extremely down and dirty (cheap) fix you could try putting a BZY91C18 (18V nominal) Stud Mount Zener Diode across the output (DC side) of the alternator. It's rated at 100W Steady State Power and 5000W Peak Pulse Power. They're about $20. Voltage will never go above 19V. Might want to include a current limiting resistor as well.

[@rylanbrowne5658]

Spot on. I was thinking a decent capacitor ocross the battery input

[@EmilyAndClark]

Caps can cause other issues. Be careful.

[@Les_Grossman]

Why not a ZVS like the 1.5KE16CA? Cheaper and biderectional?

[@EmilyAndClark]

Because I'm pretty sure it will melt. But you are free to try on your boat.

[@ar5000]

How about adding a metal oxide varistor?

[@jimb348]

Great information as usual. Your deep understanding of electrical engineering and excellent explanations are what make your technical videos so great. Often other channels, even when providing technical details, are just repeating what they were told by equipment manufacturers. Which is not all bad or wrong, just sometimes not quite all the details that we really need to understand all the issues and make the best decisions. I am looking forward to the alternator tear down. I have often seen people say that you should basically throw away an alternator if you blow the diodes and that has always seemed like it shouldn't be that hard to fix. Thanks for all the great videos. I don't even own a boat yet and may not for several more years, but I'm tempted to buy a BBMS just in case you quit making them. So please give advanced notice if you every decide to quit. But hopefully you will be hugely successful with it and keep making them.

[@EmilyAndClark]

So nice of you to say Jim. As for fixing alternators, that could be true based on the cost of US labor. And because of that culture parts are hard to find. Go someplace like the DR or Mexico and everything is fixed. So parts are readily available.

[@neilfromclearwaterfl81]

@@EmilyAndClark The Alternator parts are all pretty easy to find, at least here in the area around Tampa Bay. Alternator Starter Parts Wholesale in Port Richey Florida is a great resource for (as you might have guessed) alternator and starter parts since the owner is quite passionate about not only having the parts but also the quality of the parts. They recently got me an American Made higher quality long nose starter drive than most put into a rebuilt Marine 454 inboard and got it overnight for pickup at no additional charge. Had a nice motorcycle ride on a beautiful Florida day when I went to pick it up and was able to look a person in the eye and shake a hand. Hopefully his son will continue running the enterprise when he retires. How many folks throw out small appliances just because its cheaper to say replace a $125 portable ice maker because it costs too much to pay someone to put 3 drops of sewing machine oil on the bearings of the computer fan that was used on the condenser. We often don't think of the cost of waste on the environment when we do that and only look at the Dollars and Cents or whatever currency you dealing with. I just fixed a small appliance by taking the 15 minutes to oil the computer fan inside it instead of throwing it away and dropping $125 on a new one. That was like getting paid at a $500 an hour payrate for 15 minutes of work plus it took less time than it would have to purchase a replacement, unbox it, etc, etc along with dispose of the old one. Perhaps we should have a moment of silence for the demise of all the Emmet's and their Fix-It Shops (remember Mayberry) across the country who've fallen victim to the disposable culture we live in. Keep up the good work but don't keep working so hard at it that you don't have enough time to pause and do the simple things like comb your hair. ;> I technically gave you three likes on this one but the counter sadly only accepted the first one. Best!!!

[@Tron-Jockey]

For an extremely down and dirty (cheap) fix you could try putting a BZY91C18 (18V nominal) Stud Mount Zener Diode across the output (DC side) of the alternator. It's rated at 100W Steady State Power and 5000W Peak Pulse Power. They're about $20. Voltage will never go above 19V. Might want to include a current limiting resistor as well.

[@HitTheDirt]

Worked in power when many were new. This is also a great video for anyone thinking of building an off grid hybrid solar/mechanical system.

[@EmilyAndClark]

Thanks

[@Knuckledragnation]

I’m quite the opposite of the person below who stated they were highly trained and experienced in electrical systems. About all the training I have is enough to know sticking one’s tongue on a 9 volt battery or a fork in a 110v socket is definitely an experience I will remember for the rest of my life. To me electronics are similar to magic but what I will say sir is you definitely explained things in a way that even a caveman like me can understand. Thanks and I look forward to watching more of your videos. ✌🏽

[@EmilyAndClark]

Thanks, Please consider sharing this video if you think your friends might also like it

[@sailingjoco]

We’ve been binge watching your content lately. I love the idea of a Lead/Lithium hybrid bank and it looks like you did a great job on your BBMS product. I’m looking forward to this upgrade soon!

[@EmilyAndClark]

In just editing an endorsement video from a buyer now. So fun to see how much people like this. I think I'll release it as this week's video. He put it in a really big system.

[@davidconner-shover51]

My fix for this issue, tie in a supercapacitor in parallel to the battery. Iv'e actually blown out two solar charge controllers and nearly took out my inverter over a very similar issue. Smoke and flames, glorious flames! Many of the earlier LiFePO4 4 batteries had a lower cutoff voltage; right around 14.1 volts, the newer ones run around 14.6volts. Regardless, even if the BMS triggers, the cap provides enough cushion to allow the charging equipment to shut down safely. the supercapacitor did 2 things for me, it fixed this issue, it also allowed me to start fairly heavy motors rated at nearly the inverter capacity without issue.

[@EmilyAndClark]

What size cap are you using?

[@sgtbrown4273]

​@EmilyAndClark I tried 5F single with heavy wires like 2AWG . I also have an RZ high performing alt. 250 amps never runs over 65, though. Use a DC to DC 30 Amp charger powered by a predator engine. it's all off 😂grid stationary. so far, so good 😂🤞

[@davidconner-shover51]

50F, the sucker looks like a 6 pack

[@EmilyAndClark]

My concern with big cap banks is what happens when you get a short circuit someplace in your system.

[@CampPrevost]

I use the Sterling Alternator Protection device $80 bucks specifically made for an alternator dump.

[@dannyjensen4954]

Great Lithium topic. If you have a Balmar with an expensive external voltage regulator, you can rig a switch that allows 50% output. You can run in 50% mode by default unless you want to "fast charge". Fast charging is used on exception and prolongs the wear on the water pump pully on my Yanmar 3GM30f motor.

[@chiraldude]

For protection from sudden BMS shutdown, why not use a zener diode shunt? A zener diode is non-conductive until the threshold voltage is reached. Then it becomes a near open circuit. If you were to put a zener between the positive and negative charge wires, the voltage spike would be limited. Since the voltage spike would only last a few hundred milliseconds, the zener would be able to dissipate the excess energy with no problem. The alternator regulator will respond and bring the voltage back to normal and the zener shunt will turn off. I did a quick search and found 50W 50V and a 50W 35V zener diodes for around $10.

[@EmilyAndClark]

I've tried a zener in the past. It blew like a fuse. I don't remember the specs. Maybe there are better ones now. It's going to have to dissipate 35vx140a, that's like 5kw. That's a lot of power. The time wouldn't be the 400ms. That's how long before the alternator diodes fry and the zener it trying to protect those. It's going to be until the regulator shuts down and then the time it takes for the rotor field to dissipate. If you run the test tell me how it goes. I don't want to risk my alternator.

[@teardowndan5364]

An alternator under full load can be putting out 200+A for a few ms after the load disappears, your 50W zener will be taking 2000+W during that time. You need something more robust to take the spike. A 15V zener driving the gates of a dozen 250W MOSFETs to spread the heat and 5W 0.1 ohm balance resistors between each source and negative rail might work for clamping surges to about 18V. (15V zener + 10A x 0.1 ohm + 2V of gate drive for logic-compatible FETs = 18V) Since the name of the game is slowing down the voltage spike so the regulator can react before voltage gets out of hand, a 500 000uF 25V capacitor bank could also do the trick.

[@DrJuan-ev8lu]

You could probably put a super capacitor across the alternator to absorb the spike.

[@patrickfitzoot]

More solid content, well organized. I'm definitely sold on the Bank Manager....but I don't have any lithium yet, so that order will be awhile coming. Cheers.

[@brianwnc8168]

Your content and presentation is excellent. In the upper threshold of KZbin influencers that I've watched over many years. I hope you keep up the good work and are taking care of financially for it

[@Lana_Warwick]

From the title, I thought it's just another vid about bank manager, but its so much more. Looking forward to the tear down.

[@EmilyAndClark]

Thanks Lana

[@johnmeyer7655]

I have motorhome with lead starting batteries and lithium house batteries. When the engine is running, the Alternator charges both systems. This means the lead batteries are there when the lithiums turn off at full charge, and the Alternator is protected from damage. When the ignition is turned off, the lead batteries are completely isolated, they will not charge with shore power or solar panels. But there is also no power draw, so they can sit idle for weeks at a time. When the ignition is turned off, the 2 battery banks are cemetery isolated.

[@EmilyAndClark]

An issue you should consider is with the engine running your Li is being charged like lead (not good) and then floated at voltage over 13.48 (really not good). Are you considering a change?

[@tim1299]

@@EmilyAndClark I thought you were giving me a green light for my motor home to have a lithium house battery. Now you are talking contrary with this response. I'm left confused once again.?? So I still won't buy a lithium battery for the house side of the motor home. And I thought lithium was to be charged at 14.4 to 14.6 volts to 100%. state of charge 13.6 volts. If I am charging and floating like a lead acid battery, how would the lithium battery ever get to full charge to shut down the BMT and destroy the alternator if no lead acid battery were present?

[@EmilyAndClark]

That was in a very old video. I have learned a lot since then. That's why I developed the BankManager

[@tim1299]

@@EmilyAndClark It was posted two months ago. OLD?? remove this video!

[@EmilyAndClark]

What video are you referring to?

[@leo169]

Great idea with the thermally operated switch to control the alternator. Will store that one away for future use. 🙂

[@bhartley1024]

These thermal switches are so cheap, I don't understand why all motors and alternators aren't thermally protected. I once burned out a Makita planer just planing some hardwood. You spend all that money on a power tool and they can't put thermal protection on the motor?

[@brettschacher8644]

Referring to diode failures, back years ago, I was having issues with cheap reman. alts. I found the issue was cheap diode bridges installed in the reman's. I found a source for plasma bonded diode bridges which fully eliminated the future failure issues. The cheap bridges were soldered diodes which we all know has a low melting point. The diodes were simply falling out of the alt on the road as I drove along. Now not all alts are constructed so the diodes can simply fall out of the cases, such as late model Fords or many others. Not that long ago, I was working on restoring a Ford 7.3L powered PU which I had installed a reman alt. One day I was working on something else and sparks just lit up the inside of that reman alt. It was on account of a diode bouncing around inside the case which in the end pretty much destroyed that unit. This is the second vid I've watched today from Clark and they were both educational. I've been working on engines in boats and autos most of my life and have learned something even today after over 40 years of mechanic work. Of course very little experience with LiFePo4 batteries in cars has been the case. I'm really liking the hybrid battery concept now.

[@EmilyAndClark]

Thanks Brett. Hope you choose to subscribe and continue to enjoy our stuff

[@BigDreamsBoating]

I love the content you guys are creating. Watched a ton and I feel I’ve learned so much. I currently liveaboard but I’m new to this life. Being a construction worker I’m financially challenged but very handy. With this information I’ve been able to enter a new way of life with confidence. Thank you so very much for all the knowledge I’ve gleaned from your content. So badly want a bank manager for my Pearson 40’s solar system and I’m starting from scratch. ❤

[@EmilyAndClark]

I have a few black box 1.x units. Same electronics and software but $100 off

[@BigDreamsBoating]

@@EmilyAndClark that’s good to know because function is my only concern. Soon as the budget allows thanks

[@apollo8352]

Great video.... having the starter battery permanently connected to the alternator and hooking the lithium in parallel through a battery isolator solves the high volt issue, then with a long 10mm2 battery cable about 10 m long going to the lithium house battery gives enough resistance to limit charging current so the alternator does not run to long at full amps...which is what I did on my RV I love the vee belt comment as it was also known as a wedge belt, noisy friction stuff. I worry that the thermal switch solution may not be so good due to the inductive reactance of the field causing back emf high volts causing the thermal switch a problems..

[@EmilyAndClark]

Good point on the magnetic collapse and the switch. Could add a flyback diode to the switch to give a path. I should have thought of that.

[@benkanobe7500]

Your flat (most times installed serpentine) belt also has substantially more surface area compared to a typical "V-Belt" so it wears out much more slowly. Also, a flat belt usually has a spring tensioned self-adjusting pulley that is easy to adjust tension for belt removal and replacement unlike a fixed position pulley on V-Belts which require more tools and frequent adjustment.

[@EmilyAndClark]

So much better!!

[@stephencox4224]

@@EmilyAndClark Not always I have pulled down many engines and found that the amount of tension applied by serpentine belts shows wear on the front upper main bearing shell at about 11 o clock which shows they often have too much tension applied in the design stage, So not everything is all apples in every case

[@johnnylightning1491]

Thanks Clark, now I have to figure out what kind of alternator I have. Keep the good stuff coming.

[@paulpozboater]

Love this, thank you Clark! I've learned so much from you. Hope you and Emily are well and I'm so glad you're back on the boat.

[@EmilyAndClark]

Thanks Paul

[@bitsurfr46]

Great video, Clark! I was about ready to go out and buy a DC to DC Charger when you told us that I didn't need one because I bought your Bank Manager.❤

[@mickwolf1077]

I have a few more ideas. You can have a voltage sensitive relay that connects your lithium to your lead starting battery only when your alternator is charging the disconnects when lead battery voltage drops to its resting state. It won't matter if your lithium battery disconnects because your lead battery is still connected. You can also upgrade the BMS in your lithium battery, my JK BMS turns off charging when battery is full but still allows discharge so there should be a voltage there for your alternator to see and not shoot up in voltage, that's what happens with my solar inverter. You can also maybe have a decent capacitor in parallel with your battery to hold a voltage in case the BMS shuts off while the alternator is charging, in theory the alternator will sense the voltage in the capacitor and think its a fully charged battery. You can also remove the regulator and diode assembly in the alternator and manually power the rotor field with your ignition or a switch and connect the 3 phase stator to a 3 phase bridge rectifier to get your high voltage dc and with a suitably rated capacitor to filter the DC then connect the high voltage dc to a solar regulators pv input to simulate solar panels. The charge controller will then handle all the charging to the lithium battery. I will be trying this to make use of a fried diesel inverter generator. Great info about the overheating and thermal switch mod too.

[@marc4322]

Great info as always Clark! Happy to see I am not the only one with vbelts that goes to dust! I will do the upgrade.😊

[@detlefdaniel6106]

I'm usually not commenting on you tube clips, but i think i can add some useful info. For those who have newer boats with 2014+ Yanmar YM.. engines, they are all equipped with 125A 12V Valeo alternators, which have internal regulators - simple (dumb) voltage regulators. The video suggests to add thermal switch in the field current path to prevent overheating the alternator when LiFePO4 is used. Indeed, there is a Yanmar Tech bulletin out (YMTQTB17-007), which recommends to limit the charging current to 100A. This will limit the alt temp to 200 deg C, which seems high, but apparently is OK for Yanmar. Now, a thermal switch can accomplish this, but it does not address the voltage spike problem. Here is why. I'm assuming a typical scenario with lead acid starter and LiFePO4 house battery bank, both separated by a battery isolator. The LiFePO4 batteries typically use a battery monitoring circuit (BMC), which will shut off when a single cell (there are 4) reaches its max voltage. This shutoff happens instantly with severely unbalanced cells. The lead acid battery starter battery is normally fully recharged after a few minutes and therefore won't act much as a buffer raising the charge voltage above the 14.4V limit. The only way to remedy this is a controlled ramp down of the charging current so that the regulator can follow. So far i haven't found any specs for ramp down of BMCs, maybe someone can enlighten me.

[@brianhind6149]

Great Video ! The condition of the battery "spiking" is , I believe is known in engineering terms as "load dump " . I am amazed by how many people work in electrics or electronics, are unfamiliar\ with load dump , & its ability to destroy components. My first introduction to load dump was an automobile I had & the negative cable fell off the battery post (don't ask !) & every damned light that was "on" at the time instantly vaporized its filament.

[@adelarsen9776]

I think it's wonderful that you're helping people. Thanks Clark. :-)

[@reginaldpotts2037]

Greetings from Portugal, Europe. Not sure why your video appeared in my YT feed but nevertheless, information greatly appreciated. Thank you.

[@EmilyAndClark]

I hope you like our other offerings

[@GoCoyote]

Electrician here: The voltage spike from open circuiting a large 12 volt alternator under max load can exceed 1k volts. This is why a TVSP device will help protect the alternator and all of the electronics in such events if you have a battery disconnect switch of any sort, including the BMS. If not using a lead acid battery in parallel, I would go with an adjustable external regulator that will connect to the BMS of the battery to regulate both current and voltage to provide optimal charging within the required range of the lithium battery. One can even set the output voltage of the alternator regulator slightly below that of the PV array charge controller settings so that the array will be prioritized over the alternator, plus the output of the alternator can be controlled to allow for de-rating if overheating is occurring. I believe that there are now can-bus controlled alternator regulators that will integrate with the entire system. Those lithium iron batteries are a big investment, and one will want to get the longest life out of them. The heat created by the alternator is a function of the winding resistance, the power output/field strength, the alternators cooling fan, and the temperature and volume of airflow in the engine compartment. The reason we use alternators over generators is that they have the ability to provide a fairly large output even at low RPMs by increasing the strength of the field windings, creating more current flow in the windings, thus more heat while the alternator fan and the engine fan are operating at low levels, thus causing more heat buildup under slow RPMs. Normally this is not an issue in running basic electronics and keeping the starter battery topped off, as the alternator will just be idling well under its rated maximum output. But add a load like a lithium battery capable of keeping the alternator at max output continuously, and that can really stress the alternator. One can help overcome this by using the above mentioned regulator, and by also using electrically operated and thermostatically controlled fans to cool the engine compartment, along with de-rating a larger alternator. A 100Amp alternator will have 1/2 the winding resistance of a 50Amp alternator, and will run much cooler when outputting 50Amps than the 50Amp alternator running at its maximum output.

[@brownnoise357]

very good insights for people, thank you Clark. 👍 Personally my next boatbis likely to need refurbishing and upgrades, along with replacements, Full wiring design check, Network Wiring, Lightning protection isolation and Bonding, New instruments (replacement originals that work, kept as spares for other boaters, and expensive but worth it Alternator, serpentine belts, external Regulator, standing rigging, running rigging, New Sails, and existing checked, valeted, and kept as a backup suit of Sails if good enough. That kind of thing. I'm still a bit wary of Lithium, after communicating with a Chinese Manufacturer. Like Lead, Lithium Hates being discharged below 50% Capacity, and you lose recharge cycles each time if you do it for longer life, they don't appear to like being charged over 85% apparently, so useful non damaging capacity appears to be between 85% and 50% , so a tual useable capacity would be 35% .? Now Lead Loves being charged to 100% right? So bon damaging capacity therefore looks to actually be 50% right, plus Lead batteries are easily and fully recyclable? Plus the extra weight, can help put displacement down low where it is useful. A badly treated AGM Battery can last as little as 18 months, but we'll looked after, 10 years. How long do badly treated Lifepo4 Batteries last ? What is their Maximum Life ? Information on those factors, are highly noticeable by their absence aren't they ? So I may go with deep Discharge Dual Purpose AGM, and Never Deep Discharge them (even with Lithium, deep Discharging Damages them. Any experience with Carbon Lead Clark ? They look interesting. As an aside, Offgrid on my Smallholding, I got 15 years outbof a bank of heavy Duty Cheap Agricultural Tractor Batteries, and only lost them thanks to Not forecasted extreme cold down to minus 45 degrees C cracking their cases. Never discharged below 50% and usually a couple of volts higher than that. I won't have "Normal" Lead acid Batteries on a boat though, must be sealed. Best Wishes. . Bob 👍

[@EmilyAndClark]

Hi Bob, Carbon lead is very interesting and people I respect are having good luck with them. I haven't owned a set myself. I think you might want to broaden your research into LiFePO4. I think you will find evidence that a lot of your ideas about life and discharge are not exactly right. It's still early days for this technology but it seems to me that Lifepo4 can be fully charged as long as your charger can accurately know where 100% is. That can't be done with voltage alone so basically only my BankManager can do this safely. They seem OK with more than 50% discharge. In fact they should be stored for the long term at 50% charge. I set my lower limit to 20% so I get a working spread of 80% of rated.

[@brownnoise357]

@@EmilyAndClark Good points Clark, Lifepo4 is indeed a Bit different, to Lithium, but that 85% charge maximises the service life of mobile phone batteries and Tablet batteries may point to it pointing that way for Lifepo4 as well. It was a pretty good Chinese Lifepo4 Batteries Manufacturer (pretty sure looking to sponsor me with a Housebank Set, to help them determine what the maximum useful service life could be if properly treated ) who was quite firm about the number of Recharge Cycles being harmed badly, if discharged below 50% Capacity, if done often. I suspect there could well be a way of treating Lifepo4 batteries, to get a useful service life of 20 plus years tbh. Though Tester Will Prose has said that, or at least strongly hinted, that Lifepo4 batteries will self destruct internally, a long before Cycle life can be reached. Now That I find worrying worrying enough, to seriously consider whether even a free Housebank set is really worth the bother of testing, and is certainly serious food for thought. Thanks for the thoughtful response Clark, Best Wishes. Bob (who does love testing stuff ) 👍⛵️✨️✨️✨️✨️✨️

[@brownnoise357]

@@EmilyAndClark PS Me again Clark. I think I'm going to let others find out about Lifepo4 possible service Life, and as 10 years for AGM properly treated is now solidly established, I think a Carbon Lead Housebank with AGM e gine, bowthruster, and Windlass batteries as a setup for long term testing, will probably be the route I go , thinking about it. Thanks again. Bob. 👍 the edit was because the message decided to post itself before completion, so added the change of direction for me as well . 🤣

[@braithmiller]

Carbon lead Firefly make lithium look cheap.

[@brownnoise357]

@@braithmiller eta dropped letters from words. Luckily they aren't the only manufacturers, and Carbon Lead can be cheaper by a fair bit than Lifepo4 when on offer. AGM too, for a solid 10 year service life if treated properly, such as Never Deep Discharging any Deep Discharge Battery for starters, no matter the chemistry of its construction. You just need to develop an appropriate Battery Bank size, with a good routine for managing it. One Boat Owner, no names, no pack drill, an engineer ffs, absolutely Trashed his new AGM Batteries inside 18 months, and replaced them with very expensive Lifepo4 batteries. Did he change his management regime ? Nope, so bets may be taken on how long efore he trashes those Lifepo4 batteries. I would put money on them not lasting very long at all, and likely less than 5 years. Expensive lessons should be the best Education, Right ? Should have learned from his AGM bank that he wasn't doing things right imho, a nice guy, and he will probably figure it out in the end. 🤔

[@jemdost6724]

Such an excellent video. I'm convinced you can confirm if my expensive way of keeping my alternator in check will work for my upcoming project. Mind you I'm installing these on a yamaha jetboat (because I have a very demanding audio system) So I bought an Epoch lithium battery 12v460Ah claims the following statement on the website: " CANBUS Communication allows BMS to communicate directly with Victron OS" I also bought a Balmar XT 250 alternator. I will be buying the all new Arco Zeus external regulator (it is a canbus enabled regulator similar to the wakespeed WS500) I will also buy a victron cerbo GX. I'm hoping the Epoch batteries internal BMS will connect to the Cerbo GX to be able to enable DVCC and then from the Cerbo GX to the Zeus regulator which then will control the Balmar alternator to shut off when my lithium gets full and stops accepting charge or out of balance etc any time it shuts downs. All concept and I already bought most of the expensive parts but really would appreciate if you would look into these specific products. I have a good feeling you will be familiar with the individual items I have listed and will have a stronger opinion on if they will be able to communicate in the way I'm hoping. Looking forward to your reply and thanks for the videos, cheers!

[@EmilyAndClark]

No I haven't put that exact system together as I solve this a different (better) way with my BankManager. It can't fail and actually charges your Li correctly unlike these devices. It's also much cheaper. I suggest you ask this question to the guys buying from.

[@jemdost6724]

I see so what happens if the Lithium BMS shuts down unexpectedly, does the starter Lead Acid Battery or AGM battery absorb the extra current so it doesn't damage the alternator plus all the other electronics?@@EmilyAndClark

[@EmilyAndClark]

Yes exactly. And since my hybrid battery manager always keeps the lead on line, it's always there to absorb the energy. Nothing can fail.

[@jemdost6724]

@@EmilyAndClark amazing I’ll watch your bank manger video first chance I get to learn more

[@EmilyAndClark]

This might also prove helpful. www.emilyandclarksadventure.com/bbms

[@RichKernan]

Wow - so interesting to see how much knowledge you have on this topic. Thanks for the vid. I read all the comments and have simple question: We have a wake boat with your typical 90A alternator and a single lead acid battery that runs everything. I just purchased a Blue Sea Systems 7650 Add-A-Battery Kit ($125 on AMZN), which seems to be very highly regarded. I had planned to buy a 100AH LIFEPO4 (probably CHINS - $300) to use as a house battery to power the upgraded speakers and amp we just added so as not to run starter battery down when anchored and cranking music. My rationale being that the LIFEPO4 would be ok with getting run down, would last longer, etc. Having come across your video, I now know that the very low internal resistance on the CHINS will crush my alternator when I start the engine and the Blue Sea switches to allow the alternator to charge the house battery. Adding $380 for a Bank Manager is not worth it for my needs. Should I just forget about LIFEPO4 and get a marine battery, or maybe just charge the CHINS with a typical battery charger (one with a Lithium setting) when back in the slip and plugged in to shore power? My Battery Tender brand charger is 4.5 A and has a LIFEPO4 setting. I know it would take forever, but don't care. Thanks for any advice

[@EmilyAndClark]

Lots of battery chargers nowadays have Li modes. That's marketing, they don't charge li as it should be charged. But I bet with the project you are planning you could be fine with the li dying in 3-5 years. There are a lot of right answers in life. I'd bet that your alternator wouldn't overheat. Id try it and see how it works. Give it access to nice cooling air and small stock alternators usually run cool enough in my experience. I suggest you watch my early videos on hybrid battery systems before I developed the BankManager. It explains the method of doing it safely. I don't think the add a battery is a good safe way to add Li. One should not allow li and lead batteries to connect at different charge states.

[@RichKernan]

@@EmilyAndClark Thanks for the reply. Unless I have it wrong (totally possible) the Blue Sea never connects both batteries to the charging system at the same time. It's always one or the other. The only way to have both connect is to manually override to allow both batts to be used to start the engine if starter battery too weak. In that case, it would be switched back to normal after starting. I will check out earlier vids - thanks again for sharing knowledge. Super dumb question. If not Li, will any lead battery work as house battery in my application - or does not need to be a Marine one?

[@EmilyAndClark]

Well exactly so you discharge your starter battery and ask the blue sea to do its thing. Now your Li is dump charging into your lead AND trying to start your engine at the same time. Ouch! What you want is a deep cycle battery with thick plates to handle multiple deep discharges. Forget marine. It means nothing but wing nuts on the terminals and marketers trying to turn a sticker into money.

[@mottavator]

I just found your channel. I assume your device will apply to an RV system? I have a dual alternator system as this vehicle was originally an ambulance. I have removed the rear batteries and now have the original dual battery system for the diesel under the hood. I have upgraded one of the alternators and plan on using the other alternator exclusively for my "House" batteries which are lithium. As I understand from your video, If I install a lead acid battery as an intermediate to the lithium batteries and install the Bank Manager to regulate the alternator it should help my second alternator live to charge the lithium battery bank along with 1200 watts of solar. Thank you for this video which has come up on my youTube home page!

[@EmilyAndClark]

Yes it will work fine in an RV. In fact we just did a 3 month RV trip through the rocky mountains. kzbin.info/www/bejne/lX6TgJx3npqle68

[@4runner4ever83]

You made this more complicated. I have a lead battery as my starter battery and is using a dc-dc charger for my agm battery. I use this in a car setup. Please note i can use a lithium battery but too expensive for my needs. My agm is only used to power my fridge during a road trip and camping. I created a video on my channel about it and works like a charm.

[@EmilyAndClark]

Your needs are simple Others need different levels of performance. I, and many other commenters, believe this was just as complex as it needed to be.

[@EmilyAndClark]

Not really. Ask yourself this. What voltage do you set your dc-dc charger to? The more research you do the more you will realize there is no correct answer. You can't safely charge li to a voltage. Lithium requires a specific charging method that simply can't be met by those devices.

[@EmilyAndClark]

Yes I'm talking about lithium specific chargers of all types. They all charge to a voltage. What voltage?? It's different for every current being delivered to the li cells.

[@badactor3440]

@Emily & Clark's Adventure The Renogy DC to DC charger can be set to 4 different voltages by setting the 5 "dip switches" to a predetermined configuration. 14V, 14.2V, 14.4V and/or 14.6V for Lifepo4. It also can be set to charge LA. 12.6V, 12.8V and/or 13.0V. I'm using the 14.4V (lifepo4) setting, which is widely recommended by many manufacturers of lithium batteries, including mine.

[@EmilyAndClark]

I know. I own one. I'm saying there is no right answer for every charging rate. If you charge at 20 amps one day there is a setting that's right. Then the next day you charge while there is a load, say your refrigerator is running at 7 amps. Now you are charging at 13 amps and you need to stop the charge cycle at a lower voltage. There is no one voltage that doesn't cause low current overcharge. This causes irreparable damage to the cells. Also repeatedly not charging to full causes memory.

[@AN-kg4ei]

I just picked up 2 100A Eco worthy lithium batts and likely won't be long before wanting a BM regulator from you Clark! In the meantime I might do a little DC to DC charging experimentation.

[@EmilyAndClark]

Careful with overcharging if you charge slowly I'd set the charge limit to something like 13.8v and have it float to 13.3 right away after it hits 13.8v

[@KA9DSL]

First, you never never tie an alternator to a lithium battery. A LiPo will draw as much current the alternator can supply. A DC-DC converter is needed which has current limit capabilities. This setup has been in my Van for about 2yrs. 3-100@hr batt's. Works great!

[@EmilyAndClark]

Did you actually watch this video???

[@cabracove]

@@EmilyAndClark I did, I must have missed why this is wrong. My setup can never draw more than 40 of 160, and the alternator is never hot. The cells balance evenly. What did I miss?

[@EmilyAndClark]

Seems like your alternator doesn't have overheating issues. Many don't. I'm not sure why you are only getting 40 amps out, you might want to look into this. The bigger problem is what happens to your alternator diodes when your Li BMS shuts down during charging. That's where the lead protects your alternator diodes.

[@cabracove]

@@EmilyAndClark Its a 50 amp DC charger, but I've never seen it charge at more than 40 to 45. And that's with it hooked up on the solar side as well, but the switch off. So it lets the alternator charge at more than 25. Power going through it is supposed to be a one way thing with how it's set up but I'm gonna look into this more, thanks.

[@EmilyAndClark]

I'm personally not a big fan of dc-dc chargers. They do current control but there are cheaper, more reliable, ways to derate your alternator and of course they don't know how to properly charge lithium even if they have a Li setting.

[@ianwillcock6314]

Great video as always Clark, now that I know the bbms will protect my alternator from my lithium I can stop worrying about it.

[@EmilyAndClark]

Thanks Ian

[@bjrnetveter253]

All hail the alterntor god 🙂 Thanks for the tips. Useful.

[@bmunday]

so glad I heard about you from another cruiser. this is HQ content! Thanks clarke!

[@jroschella]

Glad to see you back on the boat.

[@StewardDIYcave]

I am going to advocate for a good DC/DC converter as the best solution. First, they can be up to 98% efficient so losses aren't a problem. it will isolate the LFP battery from the lead acid battery which have different charge characteristics. Isolation also prevents the alternator from seeing the sudden disconnect when the LFP BMS disconnects the battery. Modern LFP batteries can pull 200-250A while charging which will overload your alternator even if it is a heavy duty model. The DC/DC converter sets a limit on how much current is drawn from the alternator. Finally, a DC/DC converter is a current source which can be easily paired with solar charger current source.

[@EmilyAndClark]

Anything can be paired with a solar charge controller. A continuous duty alternator is just that. Show me a 98 percent efficient switching power supply and I'll ask you why does it have heat sinks or fans. But most importantly they all charge to a voltage. Charge li to a voltage and you will see 3 to 6 years of daily use. It's simply not the way to treat LiFePO4. www.emilyandclarksadventure.com/bbms

[@StewardDIYcave]

@@EmilyAndClark 2% of a 500W charger is still 10W and warrants a heat sink. That is just good design. A DC to DC charger is a thing and they have LFP charging profiles to optimize battery life. My point about the alternator is that if you don't have something to limit the current into a modern LFP battery you can easily draw more than even a heavy duty alternator is rated. I have a 250A alternator and I limit is to 30A max. That preserves the life of the battery and the alternator.

[@lkeil84]

Clark, loved the video. I have a very challenging problem though. My boat has 2 engines and 2 separate banks. Both banks can be charged by either alternator through a 2 alternator, 2 battery isolator. This is great when smaller similar batteries are used. My case involves a house battery bank (starboard) of lithium rated at 700 amp hours with 6 batteries in parallel. It is very unlikely that all 6 batteries would shut off, especially since the alternator really only wants to stop charging at about 14.2 volts. Since it goes through the isolator, a voltage sense wire is needed to the alternator due to about a 0.7 volt drop through the diodes in the isolator. This is one of my problems as the non house side with lead gets fully charged rather quickly essentially shutting down that alternator and now it contributes nothing through the isolator. This leaves the other house alternator doing the work to charge a 700 amp lithium battery. As you noted about alternator speed, I ussualy run 900-1100 rpm and air flow is probably not sufficient to cool this alternator resulting in a melted brush cage in my last alternator. My thought was to use a dc-dc charger from the Port Engine battery charging the Starboard engine that has the house batteries. The charger failed within about 10 hours running though. This also puts a constant 75 amp load on the port alternator at this low rpm. I am at a loss on how to get these 2 alternators to combine their strength to charge the lithium bank and have some sort of heat regulation without the 2 battery banks connected. This system was done for safety so if the house battery is depleted to a point that it cannot start the Starboard engine, then the port engine and generator battery are isolated and still full to get the generator with charger running as well as the port engine. This would charge the Starboard engine battery in short order to facilitate a start. There must be way to accomplish this without spending thousands of dollars on larger externally regulated alternators along with who knows how many other components. The temp switch may be a partial solution as I think if the voltage sense wire is disconnected, this would shut down the output and at least protect that one alternator from frying again. Getting the other alternator involved would be a bonus. Any thought by you or anyone else out there?

[@EmilyAndClark]

Wow there is a lot going on here. I'm afraid your question deserves more time and analysis than I can give here. If you would like to drill into this design I'm confident we can come up with an inexpensive system to do what you want but it will take back and forth to really drill down to the requirements. Take a look at our Patreon "Dream Believers" tier. If that looks good to you, its the right place for this level of question. For short advice. I'd start by considering loosing the isolators and using a pair of these in stead kzbin.info/www/bejne/p5TOnqVsgsyEedU They are cheap, and cause no voltage drop. Diodes were a great solution to this issue in the 70s but time has marched on.

[@patrickfitzoot]

U need to change your alt(or engine/or both) pulley so your low rpm spins the alternator enough not to overheat

[@InspiredByBrad]

Our RV (Pleasure-Way) uses the factory Mercedes Sprinter 200 amp alternator connected directly to 2 100AH Lithium batteries via a timed switched solenoid. The amps range between 90 and 130. It seems to function well.

[@EmilyAndClark]

Glad for you. Have you ever had the BMS disconnect?

[@braithmiller]

Excellent words I now won't have to type either. Thanks. Some have played with varistors temperature compensated. A few sailors tired of the cost of the potted voodoo regulator went hardware simple despite being programers. I have a VSR daisy chain working well till more money. No heat at all. Your BMS in on my wishlist.

[@ericdelevinquiere9902]

Personally I like the idea of regulating my power input from alternator to LiPO, even if it cost me a little power. It will extend the life of your alternator and battery if you have a well matched system. No need for lead batteries, could even use capacitors to start your engine.

[@brnmcc01]

You can't use capacitors, they can deliver an insane amount of amps for only a very short time, and then they present a total dead short to the charging system... As far as "regulating" the power input from alternator to the LiPO, all you need is a battery that has an actual 'intelligent' BMS system, or just get a battery from a good brand like Victron energy. You get what you pay for.

[@ericdelevinquiere9902]

@@brnmcc01 done this 10 years ago on my beater car, no issues just looses charge after a few weeks but if you can recharge at will not an issue. What do you think solid state batteries are?? Victron is expensive and you can do the same circuits yourself at least that way you will have knowledge and recourse when it brakes down ! If you gonna try this today just be careful with your circuit protection, new stuff is uber sensitive to intermittent voltages, like you can fry some components especially memory.

[@neilrasmussen2063]

​@brnmcc01 Bombardier uses a capacitor to start small 2 stroke engines currently in production. I don't know enough to know how that scales, but it does exist.

[@tiny3669]

I run a dual alternator set up and have my battery bank on a 375 amp alternator with a external adjustable voltage regulator. Works great.

[@EmilyAndClark]

I don't understand. Alternator hooked to battery works. Of course it does.

[@jimjones7821]

@@EmilyAndClark Clark, I think he is just saying that he has a system setup as he notes and it is working out really well - thats all. I dont think he was posing any sort of question at you.

[@EmilyAndClark]

Thanks, after reading and answering hundreds of questions I guess everything starts looking like a question.

Very informative. Interesting approach. Personnaly I would probably use a slightly different approach. For the charging: Having a lead starter battery and wiring in a charge controller that draws from that battery and the alternator, combined with a low voltage shutoff setting, so it can not drain your starter batttery. Easiest is probably a solar charge controller that can handle the voltage of the alternator. regarding the heat issue it depents on how much power you want to draw, either have an electric fan controlled by the alternator temperature that adds cooling when the tempt gets too high, or, preferrably, use a liquid cooled alternator, that is cooled by the engine cooling system. This is especially useful for high power alternators that put out power in the Kilowatt range and can charge large battery banks. not the cheapest solution, but the cleanest from a technical point of view and with minimal additional effort since you need to cool the engine anyways and engine temperatures are in a similar ballpark or lower than the allowable temperature for your alternator. Of course this approach is useless with aircooled angines, but those are rather rare in marine applications. Benefit of using something like a victron BlueSolar MPTT 100/50 with a 24V alter nator and a 12 Battery bank - or a 48V alternator and a 24V Battery bank is that it will not just limit the current to what it is specced for (you can use more than one in paralell if needed, but it can deal with the BMS and its shenanigans and protect the alternator. if used with a seelctor switch that allows to swithc to solar input it could also act as a spare charger in case the main solar charger is damaged. in that case you just move the voltage source fron your alternator to your panels - or some of oyur panels to keep the voltae with in the spec.

[@bendegroot8234]

Victron tells dont use a mppt as dcdc between two banks. They have another product for this the Orion dcdc.

@@bendegroot8234 if they have a dedicated device for that, even better.

[@jimanderson4444]

Good work Robert, I like the solar connections . An offgrid system and my old Toyota ice running some big water cooled alts for backup has been my plan. Jim.

[@philbrooke-little7082]

Most BMS only disconnect charge. So if the BMS disconnects and destroys the alternator the power doesn’t go out as the the battery discharge mosfet is still turned on. A big alternator will produce less heat for a given amount of power owing to its lower internal resistance. Another method that works is to find the continuous happy current of the alternator and you then extend the charging cable to add enough resistance to reduce the current. F have a 14.2v Alternator then you subtract the lithium voltage it spends most of its time charging at which is around 13.6v so you just need to drop 0.6v at your chosen amps. Many systems already drop this anyway but it generally doesn’t need much extra cable. An advantage to this method is that it also produces a short current taper towards the end of charge which is what the cells like. This is one place where resistance in the charge circuit works to your advantage using the very flat charge curve of lithium in order to work. I can now say from my own feedback that dozens have used this method in hybrid systems to good effect. So long as the correct cable is used that can safely carry the max output of the alternator then no rules are broken. I too believe that DC-DC chargers in this situation are the spawn of Satan. I’ve just scribbled the software and built the hardware for a regulator that can measure voltage, current and temperature and regulate based on all 3, I only did it as I got a 180A smart alternator for £20 where the internal regulator is useless as it’s controlled by the car management system and so had to be bypassed anyway. It’s really stupidly easy and cheap and has wifi monitoring and setup.

[@martinsonneveld440]

Thanks for discussing this! But why so hard on DC-DC Converters? Yes it's another green or blue box but I installed one it works flawlesly and doesn't need a lot of attention, you can easily adjust on charging profile, set voltage, amps, duration so it can nicely work together with what you already have. No need to fiddle with alternators, easy install and not more expensive than alternator and regulator upgrades. Very easy to live with last 2 seasons, and solves both issues you rightly brought up here! While Lithium takes a charge so easy you hardly have to max out on alternator power, In parctice I rarely draw more amps than 1/4 of the rated alternator output (115A), most of the times its set to 25A.

[@EmilyAndClark]

I have used dc-dc chargers. Sometimes they are a good solution but usually they aren't. My issues: They are mono-directional. Can't move solar power to the start battery. They waste power (minor issue with power to heat but major issue since they can't pass much power. As you said seldom 1/4 of the power available. They don't charge li correctly. They charge to voltage not to full. See my recent video on the BankManager for a definition of low current overcharge. They are basically unnecessary. Hybrid batteries are better if managed property. But we are all captains of our own ships and should do as we wish.

[@martinsonneveld440]

@@EmilyAndClark true, all choices are personal, only wanted to add my positive experience here.. to react to your points: I connected the solar power to a Blue Sea 1-2switch (after the solar charger) to choose banks manually. When not aboard it is switched to the lead acid starterbattery. The DC-DC Charger can be set to stop charging the Lithiumbattery ones Tail-current thresholds are reached, in combination with the apllied voltage (eg 14,0 Volt at the Li-battery), just like the solar charger or the shorepower charger (all monofunctional on purpose). I am least worried sofar on the efficiency of the setup, more to (losing) simplicity and how to save or enhance some sort of redundancy. I am very interested in your creative solutions and will sure look into the benefits. Many thanks for your time and efforts!

[@EmilyAndClark]

Which dc-dc are you using? I've only tried the renergy. Be careful with the battery combiner switch. If your lead is quite discharged li can try to send LOTS of current into it. We have seen some smoking wires during tests.

[@martinsonneveld440]

@@EmilyAndClark I installed the Mastervolt MacPlus 12/12-50 2 years ago, as part of a total overhaul of the electrical system. Can also act as a stabilized (max 50A) DC-source, so if Lithium is down engine can be used as generator (for basics: nav, autopilot, lights etc, not microwave). This Blue Sea switch has deliberately no combiner function, it is in to be able to maintain control over the solar charging.

[@EmilyAndClark]

Thanks

[@sifilmaker]

This is how RVs are setup.. lithium batteries are connected to the started battery through a DC-DC charger. BMS are pretty stable nowadays, even the old crappy Chinese ones have become better and beefier than ever. The price of lithium batteries have dropped dramatically if you are running Lithium you should have an alternator that has a higher output. Best days of a boart owners life, the day you bought it and the day you sell it. I loved my boat but man was I glad I got rid of it. lolol Nice video..

[@EmilyAndClark]

That's a way you can set up an RV. My camper uses the BankManager approach as you might expect. Once you take the little life jackets off the electrons, boat and RV electrical systems are very similar.

[@ar5000]

This may explain a similar problem I'm having. I recently replaced both batteries in my wife's BMW. One was toast, the other, 5 years old, but still working fine. It's worth noting that these two batteries look and feel like a regular car battery, except they are $350 each. Something about the battery having a BMS made them so pricey. About the same time, I bought an old boat and needed a battery for it, so I just used the BMW battery. After a few months, the alternator on the boat started putting out 18-20V. It was the original alternator from 1995, so I replaced it without much thought. A couple months later, now my new alternator is also outputting a 17-19v. I'm starting to think the BMW battery is killing the alternator voltage controller.

[@EmilyAndClark]

Batteries with a BMS can just turn off. Alternators hate when you remove their battery. All your other electronics hate when alternators have a bad day.

[@robertmorris9998]

Don't know if you'll see this there are a lot of comments, but here goes. I have a semi truck, with 4 starting batteries, and 2 house batteries for the sleeper. They used to be deep cycle, but I recently bought lithium, thinking it was the way to go. My mechanic called and said he wasnt sure if they would work with my isolator, and could I check. Days later, down the rabbit hole, I find that maybe a DC to DC charger is what I need. But then do I hook it to the starting batteries as power in, or to the alternator? No concrete answers found. Then I saw your video, and your little gadget. Can you help?

[@EmilyAndClark]

Yes I can help. The BankManager is specifically for making a hybrid battery system between LiFePO4 and, well anything, but lead is the most common. The only rule is you need some lead always connected to the lead side of my contactor. This could be your starters (they won't be cycled but if you discharge your Li your starters are next). Or a small lead on the house side of your isolator. That lead could be a car starter battery. The lead on the house side is to keep whatever charge controllers you have "same" when the BankManager removes your Li after full charge. The BankManager will charge your Li the way it should be charged for long life unlike any other charge controller on the market which are just lead controllers with the absorption time set to 0. www.emilyandclarksadventure.com/bbms

[@coachgeo]

THANKS for putting this video together.

[@EmilyAndClark]

You're very welcome

[@EmilyAndClark]

Hope you enjoy our other videos as well

[@coachgeo]

@@EmilyAndClark been thru them numerous time and purchased (but not installed yet) a BBM+

[@cliffweinan3907]

Good point about loss of battery load killing alternator, especially on diesel with no engine electical load. How about simply keeping the alternator / regulator always lightly loaded with a couple of engine comparment light bulbs?

[@hyperchannel4048]

You can buy alternators with watercooling. But power is amps times voltage and torque times rpm so lower rpm needs more torque and a stronger field. That wears out your alternator. You can chose the pulleys in a diameter that gives your alternator more rpm even during idleing. But keep an eye on the bearings. At sea there is.nothing more reliable than a standard alternator and a standard lead acid battery to keep you able to start the engine. Keep that in good and original condition. Make anything else with a second alternator and its own belt. The guarantie and the insurances will tell you that anyway. You can protect your system against overvoltage with a varistor or surpressor diodes. A save and dry stored spare alternator and a magnet is worth its weight in gold. Have you seen the new capacitore based jumpstarter? Supercapacitors are able to start your engine. With an step up converter and a solar panel or a weak battery you can always start your engine. But do not shortcut or overvoltage them. A lot of.information here thanks for sharing!

[@brianbuchanan5170]

The communicating BMS, as should be the standard, interrupts the regulator. It could be as simple as a relay breaking the wire that energizes the alternator. A smart BSM will actually test and validate charge control functionality on a periodic basis. Actually disconnecting the battery should be the absolute last resort. Now it’s not only the alternator that can cause issues but solar chargers, generators, or shore power chargers. All of those potentially need to be slowed/stopped. A second method to slow charging equipment is to have a step-up DC signal for the voltage indicator at the BMS which can suggest to older equipment that the battery voltage is higher (such as 15 volts) and allow the equipment to slow charge that way. The problem is the inexpensive lithium batteries are designed to be small, cheap, and modular without considering how to protect the whole system. It’s much easier to package a whole “replacement” battery instead of individual cells and a single common BMS - one using relays and a shunt or two instead of relatively high resistance mosfets.

[@EmilyAndClark]

Your statement seems like an argument to do it my way. Easier, cheaper and pretty bullet proof.

[@jackpatteeuw9244]

And even simpler solution. Leave your existing or upgraded alternator connected to your existing flooded lead acid engine starting battery. Buy a dedicated DC-DC lithium battery charger. Wire it between the 2 batteries. It will "properly" charge your lithium battery through multiple steps. If will also prevent any damage to your FLA and alternator. Yes, these DC-DC chargers LIMIT the current to the lithium battery so it will take longer to charge.

[@EmilyAndClark]

They also cause low current overcharge damage to the li

[@ii1825]

DC/DC chargers are bad for LiFePo batteries? First I've heard of this. Care to expand on this? These type of chargers are used all over the place in overlanding vehicles and I have not heard many if any complaints. Shouldn't matter if it's a land or sea vessel.

[@EmilyAndClark]

Read Conrad's article linked to the bottom of this www.emilyandclarksadventure.com/bbms As a start to research. All chargers currently available (except mine) cause low current overcharge which seems to kill LiFePO4 in as little as 3 years. Li should live much longer than that.

[@ajf9034]

@@ii1825there is nothing wrong with dcdc for lithium housebanks, it’s the simplest and safest way to charge a lithium battery from an alternator and their regulated charge current will lead to the longest life possible as regular rapid charging decreases battery life even with lithium, any reputable lithium battery manufacturer may allow a 100 amp max charge for example but the recommended charge current may only be 30 amps for maximum longevity. Old mate here needs to try some redarc or Enerdrive products which have adjustable tail current so low current overcharge is not a problem. Keep it simple, lead acid start battery or batteries and a lithium house bank charged by a dcdc charger with an inbuilt mppt solar regulator and a shore power charger.

[@dalegimben4448]

I was unaware about blowing my alt when the lithium is disconnected. Luckily, my truck AGM battery was there. Our Renogy DC-To-Dc converter failed out of warranty, but only a few hours use and I didn't know until the house battery was at 10.2 V. (We have a pull-behind trailer I've converted to lithium so it has a private hi-current plug for charging). Once at the campground, I ordered a 100W/ 0.1 Ohm resistor and wired it in series with the charging ckt from the alt. Renogy won't repair and I won't re-buy so I made up 3 switches and 3 heavy relays; one for direct, one for 0.1 ohm, and one for 0.2 ohm series resistance. So far at max draw we drop about 3 volts across the 0.1 ohm resistor, but as the battery charges, the current goes down, and the drop is less. I already have a 50 mv shunt current meter on the dash so I can monitor charging current. I don't care if the battery doesn't fully charge while on the road. We seldom dry-camp more than one night between campgrounds. But by switching resistors, I can fully charge my lithium, protect my alt, and not have to hassle with Renogy. All for less than $50. and I can fix it if it breaks.

[@dyslectische]

Cheap and easy way ? Pwm controller with lithium support . Done . You connect it to your lead Battery. What u use for to start the engine . And set it on your Lithium. Switch to set it on or off . If you go full lithium than u use dc to dc converter. If you have low power alternator like a small one outside engine you can use a pwm .

[@EmilyAndClark]

It's not that simple.

[@grakkerful]

Well, I picked up some thermal switches. Looking forward to the next video so I can learn what to do with it.

[@EmilyAndClark]

Someone suggested a potential problem with this. He might be right. Adding a flyback diode might help protect the switch for longer life. I'll talk about it in the description of the next video. Too late to film anything.

[@grakkerful]

@@EmilyAndClark I'm looking forward to it. I recently upgraded to 200Ah of Lithium (27' sailboat) and I've been a little worried about how the rest of the system.

[@EmilyAndClark]

I just updated the description of this video to talk about it. I basically said check wikki. What I really should have talked about in the video was venting the engine room. I think I'll add that to the description now.

[@lloydevans2900]

How about this for an idea: Get a 12 volt powered fan (like an old car radiator fan) and position it so that it's blowing extra airflow directly at the alternator. Then wire up the fan through the "normally off" contacts of a DPDT relay, with the relay coil powered from the alternator output through one of those thermally activated switches - with the switch mounted to the hottest part of the alternator of course. That way, if the alternator does overheat and turns the switch off, this will turn the relay coil off and therefore turn the fan on, blowing extra cooling air over the alternator. Or, if it's possible to get a type of thermal switch which which turns itself on when the rated temperature is reached (rather than off, as the type you described does), you could dispense with the relay and just wire up the fan directly through the switch. I had a similar setup several years ago on a rotary vane vacuum pump in a chemistry lab - the pump was old but still worked most of the time, probably had slightly swollen vanes so the motor had to work harder than it was supposed to, so it would overheat, especially in the summer. Like an alternator, the motor had its own integral cooling fan, but that wasn't enough, so I rigged up a couple of 120 mm brushless fans to blow extra cooling air over the motor, which stopped it overheating. The pump had its own thermal cut-out of course, which would save the motor from catastrophic heat damage, but that was a last resort since keeping the vacuum running was the main priority.

[@EmilyAndClark]

Yes. I wish I had mentioned the obvious solution. First improve cooling! Those switches are readily available as NO and NC

[@ScottMason-ss8ww]

They're being put on narrow boats on British canal system... The average boater cat afford these batteries. A decent solar and lithium costs about 10k! Most of us living on both couldn't afford them if we wanted to! Great information to have though.. Thanks!

[@EmilyAndClark]

Yes I've heard back from a lot of narrow boat owners with BankManagers installed. Not having to basically scrap your existing system makes going Li a lot cheaper

[@Kosmonooit]

The charging voltage for Lead Acid and Lithium is different, that's why a DC to DC charger for the Lithium is a good idea. Also higher than rated charging voltage for Lithium can shut down the BMS

[@EmilyAndClark]

For the best answer to all this check out www.emilyandclarksadventure.com/bbms

[@MikeSantis]

Fantastic. Thank you Clark. You explain things in a way for us that don't know much about this stuff so we can understand.

[@EmilyAndClark]

Thanks Mike

[@fc436]

i have an alternatorCarGo (Bosch group) of 65A. But the power curve in data sheet say clearly that at lo RPM don't produce more than 25A. So, at the stop or streetlight red, in bed cooling conditions, no danger for alternator. And its not depend from type of battery. not even short circuit can produce full current. Another thing. Lifepo4 battery have a very high voltage already less than half SOC. If the voltage on battery terminal don't if it does not exceed the same battery voltage, the charge current will be null or minimal. Because a thin section of cable maybe with 60A cause a drop from 14.3v on alternator and 13.4 on the battery terminal. Supposing a 150A alternator. These means that the lifepo4 at 60% Soc don't will charge if not with a very small current. The problem would be with a very big cable eventually. I've seen camper of my friends with decent cable, but some problem in voltage regulator of the 90A alternator. The 280ah lifepo4 at 40 -50% SOC don't take more than 15A. And at higher Soc almost 0 Amp. Obvious, the voltage on the battery was no more of 13.5v victron produce a smart relais (cyrix LI ct) to charge lifepo4 battery directly from alternator. i charge my 150ah lifepo4 directly from alternator, with cyririx. Never problems. At low rpm or charge 20/25A without big loads, or with big load , the battery partially gives current in collaborations with alternator to loads. its more, when I have AGM, at 50% SOC , for 2 minutes they take more current then lifepo4. Because de difference between the applied voltage and battery voltage was more, respect to lifepo4. Despite the internal resistance in liofepo4 is almost 10 time less. mastervolt produce a 3 -Fhase voltage regulator for bosch compatibles alternator. 3 step charge but without current limit. I hate the very popular dc dc of 20 or 30A in RV with 300ah lifepo4 battery pack and 200A alternator. If you set off on a journey with 2 e-bike, a fridge, an evaporative cooler, you've already finished all charging current of your expensive dcdc. Maybe with 200A alternator. And a 100 0r 150A dc dc are crazy expensive. my system with smart battery combiner (lithium version) work PERFECTLY

[@larrydugan1441]

Excellent video Clark. Really informative. Thanks

[@EmilyAndClark]

Nice of you to say Larry

[@kb9knd]

I enjoyed this video. The idea I had when you were talking about using the lead battery to protect the alternator when the lithium battery opens it’s circuit and stops charging was, would one of those super sized capacitors used in audio amp installation work in place of the lead battery? The capacitors I’m talking about are over 1 farad and some even have digital voltage displays built in. Capacitors life generally lasts longer than lead batteries. Just a thought. Thanks for the interesting video. This is the first time I’ve seen your channel.

[@EmilyAndClark]

Technically it would solve the problem nicely. But,, it creates so many problems of its own. It's hard to control current with one of these. Its charge acceptance ability is scary.

[@overlandready]

All alternators have a regulator, so that limits the voltage the vehicle sees, that will remain at no more than 15VDC! What does actually happen is the battery draws very high amperage, as the volts DROP off, as the BMS regulates the Watt input to the battery. The alternator is not destroyed by Voltage, it is destroyed by HEAT! ps an alternator produces about 250vAC then regulates it. You can use an alternator to run a mains generator. The simple way to stop the Lithium from cooking your alternator is fit extra and efficient cooling, secondly fit a volt sensing device that has overvoltage as well as undervoltage cut offs, have a smaller sacraficial L/A battery so the alternator is not subjected to heat spikes from being disconnected, The other MUST is a ingition relay that instantly removes the lithium from the systen when the engine is shut off, this avoids the amp spikes when shutting off. A DC/DC inverter cahrger is the easier and simpler way to go and honestly, the losses are not really an inssue unless you are already maxing out your charge system which is not good. I normally allow 10% for inverter charger losses.

[@kmnl926]

Add capacitor 10000uF/25V to your alternator. Will allow regulator to work and prevent over-voltage output from alternator when BMS turns off battery.

[@EmilyAndClark]

Could do. Have you done this?

[@kmnl926]

Yes but give it a test for your application. Run alternator with battery and cap. Disconnect battery and verify that alternator still works afterwards. Reconnect battery and charging from alternator will resume. Good luck.

[@EmilyAndClark]

No thanks.

[@rylanbrowne5658]

Spot on

[@71970eli]

Brand X alternators can make you an alt that will have zero care in the world while charging your lithium battery. They make an alternator for just about any engine with amperages rating from 180A- to 540 amps.

[@Eduardo_Espinoza]

thinking of parallel connection (pbo2 & lifepo4), alternator connected only to pbo2, hopefully balance-charging changes the lifepo4 battery too :). thanks for bringing this to our attention :).

[@EmilyAndClark]

You should consider the BankManager for that. www.emilyandclarksadventure.com/bbms

[@my_channel_44]

This applies to motorhomes. KZbin recommended it. Leaning on the Dakota Lithium DL+ as a direct replacement.

[@EmilyAndClark]

Yes. And consider the BankManager. It not only treats your new li right it lets you keep your old lead charge controllers In an RV the engine alternator and the AC charger are particularly hard and expensive to replace. www.emilyandclarksadventure.com/bbms

[@svestancia]

I’ve always asked myself if a blackout was possible when BMS disconnects.. wasn’t sure if it only disconnected from incoming power or disconnected the whole thing.. now is clear.. doesn’t sound good to electronics and a little annoying..

[@Mountainmandean207]

i love your videos as a new sailor the are so valuable thanks

[@retiredguyadventures6211]

Great video! I am new to lithium batteries. I had an AGM battery in my cargo trailer hooked up to the alternator from my tow vehicle so it would charge along with the tow vehicle's battery while driving. I recently bought a LiFePO4 100 AH battery for the cargo trailer because I want to put a solar charger on it, and it has a 100 amp BMS rating. Basically I had the cargo trailer AGM battery in parallel with the tow vehicle's lead acid battery for charging off the tow vehicle's alternator when driving. I have a couple of questions. #1 - Can I even put a LiFePO4 battery in parallel with a lead acid battery and charge off an alternator? #2 - If I can put the two batteries in parallel will the tow vehicle battery act as a shunt to prevent the voltage spike when the LiFePo4 BMS shuts off?

[@EmilyAndClark]

I have several videos on this topic . You can do it manually but it's best to use my BankManager if you want the best life from your batteries. I suggest you watch through my videos on the topic. Check out playlists.

[@tracker001]

Sailing Yaba , needs to see this !

[@tonyrebeiro]

From what I understand, you are dealing with a spike, that happens because the AVR on the alternator is not quick enough to cut exciter current. You say that the spike is about 400mS long. I have not tested what I'm going to say, on this particular case but I know it will work, because I've used it in other places to achieve the same function. You can put a 20 volt, (for a 14.8V system)80F Supercap bank in parallel to your alternator output. This setup should be able to absorb the spike, thereby ensuring that the voltage is within manageable limits. Supercap banks are capable for absorbing a good deal of energy and stabilize your DC bus.

[@EmilyAndClark]

Yes a capacitor bank can absorb this energy. They are great at sucking down big current. But at what cost. Lead does the same thing and has loads of other benefits. One down side of caps is they can discharge great pulses of current. Say you do this and then connect a big inverter. The discharge from these caps to the caps in the inverter will cause a possibly dangerous current flow. Then you find yourself having to deal with current flow issues.

[@tonyrebeiro]

@@EmilyAndClark No. Nothing like that will happen. Trust me. I have 35 years of experience, fooling around with these things. That's why I suggested using a Super Cap. This small 400mS surge pulse will hardly make a dent on the VOLTAGE across the Supercap. So, your explanation about the inverter and a surge etc is not relevant. Moreover, most modern Inverters have PWM based DC to DC converters on the DC side. So, if there is a small rise in the DC voltage, the input filter capacitors and converter will absorb it very easily. These kinds of 'Dangerous' current flows can happen if the voltage surges, but if the voltage is within, say 10% of the nominal input voltage of the Inverter, NOTHING will happen.

[@jase1911]

As a great option for a upgraded alternator MECHMAN has up to 400 amp alts. & definitely worth the price

[@EmilyAndClark]

That seems unbelievable

[@rickcreel3657]

Some BMW alternators are water-cooled with the cooling system coolant. You would have to make a pot to fit the alternator in with an 0-ring seal.

[@davidelliott5843]

I tried an LFP on a large motorcycle. It worked extremely well and the alternator seemed to cope just fine. But the battery failed far sooner than it should. I had the exact opposite problem. Bikes can stand unused for extended periods. LFP handles disuse better than lead acid. However, lead just gets its life shortened. LFP at low charge is shut off by its internal protection. The small remaining charge soon drops below the critical voltage and your battery gets bricked.

[@EmilyAndClark]

Yes I have the same issue with the LiFePO4 in my 1.7 liter Roadster Warrior. I leave the bike for years at a time while out sailing. If you have that bricked battery you likely can recover it. A modern battery charger will detect it as dead beyond charge but if you use a bench power supply (or just parallel it with another battery) it's BMS will likely wake up. Get some ah into it and your regular charger will be able to take over from there.

[@timchambers5242]

Some external chargers can charge "flat" LiFePO4 battery (fallen below 2.5V/cell). Will wakeup BMS & get it working again once it's over 2.7V/cell. Better to recharge to atleast 3.3V/cell before trying to start a motor. Most LiFePO4 have a 1C continous, 2C peak for a few secs (eg. 10Ah has 10A BMS with 20A max). SLA often allow 8C peak discharge for 5-10secs to start engine with no BMS (no limitations). YMMV. DC-DC charge controllers can limit charging rates & taper current when closer to max voltage, boost lower supply voltage or prevent charging while starting engine. Yes, it's complicated.

[@hinoonenterprises]

Do I need a new voltage regulator?

[@trevortrevortsr2]

Narrowboats have this issue - their solution is to put the lead acid starter battery in parallel with the lithium house battery and throttle the current by making the parallel wire connection to lithium with about 2 -3 meters of 10awg - this is crude it relies on the voltage drop across the long 10g wire to reduce the potential difference and thus reduce the current - the wire needs to be silicon or similar as it will get warm!

[@EmilyAndClark]

They should try a BankManager www.emilyandclarksadventure.com/bbms

[@Nicedesk]

Great info thanks!!!

[@termiterasin]

My new favorite gear is the Renogy 50A DC to DC charger with MPPT. For $300 there is nothing that is a better value. 50A of solar or 50A of alternator charging for any battery type and very safe for lithium.

[@EmilyAndClark]

It causes low current overcharge.

[@stanleybest8833]

If I had to deal with lithiums, I'd just introduce a heavy resistor such as a giant tungsten light bulb. On land, I favor dilute acid lead batteries and I often tell people no batteries wired in parallel. Bigger systems? Separate charge controllers. Separate batteries. Separate loads. If your battery won't charge on a Delco 10, it's not 12 volts. I can easily charge your fancy 100 amp lithium with my Sichuan Sifa MB168F 3 horsepower diesel. Adapted shaft up to 1 inch, it will take a common 7 or 8 inch pulley. Turn a common regulated alternator with the governor throttle on 25%, and the slower diesel load will just settle in. When the battery voltage climbs high, the RPM's won't follow. On a sailboat, you've got to have a small generator. Your solar space is limited and there are storms and cloudy crossings. Even deserts get their cloudy week. You don't want your food ruined.

[@EmilyAndClark]

Yep. But remember your resistor eats power all the time And Li isn't lead. There is more to it if you want them to last

[@stanleybest8833]

@@EmilyAndClark No. The resistor only uses power during charge. A small price to pay for peace.

[@EmilyAndClark]

@stanleybest8833 yep, I see that working. What problem do you have with what I suggest?

[@sailingrumrunner]

I have a Yanmar 56hp diesel which I think has an 80amp alternator. My starter battery is two 6V deep cycles in series for 12V. I have a victron 18amp DC/DC converter fed from alternator to two 12V 206ahr SOK LiFePO4 batteries. I like the idea of the thermal switch and having spare diodes on board. Any advice or critique here? BTW, really love the way you explain things. I am a retired chemist and typically chemists and engineers don't see eye to eye. My eyes , and ears, are wide open. Thanks Captain Qwiksword SV Gratitude Cocoa Fl.

[@EmilyAndClark]

Thanks. I'll assume your request for discussion is for others as I'm on record. Also glad you read about the flyback diode.

[@nordic5490]

Ok... when I use my big air compessor in my 4wd, this thing draws 90A from the battery with the engine running, pulsing on and off, and the alternator doesn't blow up (and pumps the tyres up fast). I used to be a surveyor out in the remote part of nothern Oz (NT), and once a month or so, I had to use the winch to get out of a bog, no Idea of the winch current, but, I think 200A would be in the ball park. On off on off... and the alternator didnt blow up on 2 80 Series landcruisers, and on 2 GU patrols. I never heard of an alternator blowing up this way ever. No one has mentioned it. I Was working in the NT for several years. And some are very hard on their winches. So, if very high loads, eg 200A can be pulsed on and off with the alternator running, plus all the back emf that ensures, and the alternators survice (they all do on 4x4s running winches and big compressors in the bush) , then there is no way a nice gentle easy peasy dcdc converter, with its soft start, can damage the alternator by causing overvoltage ramping the battery itself has verylow internal impedence and is a massive 13v clamp. Did you put a scope across the 12v to verify this theory ?

[@EmilyAndClark]

As I say in the video a good continuous duty alternator should have no problem with overheating if installed well. The problem is on boats the owner falls for buying a hugely rated alternator. Something that can put out 170amps but is built in a small alternator case has trouble cooling itself over hours and hours of full performance. Sure a dc-dc will solve this by imposing its 40 amp current control but it has loads of other problems. The bigger threat to alternators is (as I describe in the video) when the BMS removes the lithium batteries suddenly from the charge system. With your experience you must know that suddenly removing the batteries burns out the alternator diodes??

[@jjjoooojjj]

Thank you Clark for this excellent episode. I have one question though. What if I have starting battery Lithium as well. Please let me know..

[@EmilyAndClark]

I don't recommend that. The major reason I developed the BankManager approach to a hybrid battery system was to use each battery chemistry to its strongest advantages. With all lithium you loose the passive alternator protection and honestly the cheap easily replaceable starter battery (I bet that li starter cost a mint!) As well as a reliable battery system to fall back on. We went into all that pretty deeply in the document the ISO asked us to write docs.google.com/document/d/1a5M0V9JjaMezCZjJwrGv0IhCekAy-r_X6PPKs1YG8dY/edit?usp=sharing If I were you I'd use a lead starter battery. Something like this. kzbin.info/www/bejne/jqGZpKahaayoq8U

[@hiteck007]

Mate I've killed 2 alternators with an AGM 2nd battery and a DC to DC charger. We suspect somehow the alternator Overheated even though it's only under a 40% load. Alternators are rubbish these days, since I got rid of the DC to DC charger, no more blown alternators.

[@chrissmith2114]

The main problem with lithium based batteries is that because their terminal voltage is not a good guide to SOC they need a control board to measure amps in and amps out to tell the SOC. This is called Coulomb counting and even small devices like phones and shavers need it. I had a Li-Ion battery go bad in a Philips shaver, so I got a new battery - charged it up outside the shaver and soldered it into place, I was shocked when the red ' battery low' red LED started flashing and shaver would not run (remember I fully charged the battery before soldering it in )... What I had to do was unsolder the new Li-on battery, discharge it with a 5watt 12 volt incandescent bulb, fit it back into the shaver and charge it fully inside the shaver... once charged the battery performed great, and has done for years since... So lithium is tricky, its coulomb counting charge circuitry is everything.

[@EmilyAndClark]

You are right. And many battery control circuits use the coulomb counters like your shaver (kudos for replacing your battery and not the shaver). But as you can see that method has faults. Chief fault is that coulomb counters aren't perfectly accurate and tend to drift. Using them to find 100 percent charge can easily lead to 110 percent charging and battery failure. So those control boards tend to stop at 80 for safety which not only wastes capacity but causes memory conditions in the battery. The BankManager has a coulomb counter as good (or better) than any but I don't use it for charge termination. In fact I reset the coulomb counter upon charge termination. I've developed a multi dimensional equation that has been proven to take LiFePO4 to precisely 100 percent. It can also be targeted to lower POC levels. The BankManager does a lot of useful things but the ability to charge LiFePO4 correctly is the one I'm most proud of.

[@fsj197811]

Well done, thanks for sharing.

[@EmilyAndClark]

You're welcome