Can you run Lithium and Lead Acid batteries together? Let's find out!

I'm was tired of getting conflicting answers on if you could run lithium (specifically LifePo4) batteries and lead acid together without an isolator - so I went out and bought a lead acid battery and hooked them up.
Check out our brand new "Series 3" battery here: glowevoltage.com/shop/batteri...

[@garyveitch4222]

I’ve done this with 4 100ah lead acid batteries and 1 LiFePO4 100ah battery. My setup is in an RV and the best thing about it is that the Li battery gets all the load and the Lead Acid batteries are sitting is a float mode all the time. The lead acid batteries only get used in periods of low Solar charging. This is a win win setup.

[@pieterbezuidenhout2741]

Now that makes more Sense to me than a ' Learned ' statement. Okay now let's bring in a bank of SUPER CAPS into the equation to realy handle the PUNCH of say a Starter motor. How long will such a setup make everything LAST Longer ?

[@MegaCyrik]

@@pieterbezuidenhout2741 if mainly for a motor i suspect LTO batteries could handle it. They are quite good in charge discharge and cycles.

[@GloweIndustries]

We just did a 2,488 amp hour (@ 12.8v) build for an RV with LifePo4!

[@richardyao9012]

@@MegaCyrikLTO definitely could, but have fun finding one in a standard automotive form factor, especially one that you use, at a decent price. I saw a forum post once about a guy who got one from China at a decent price, but the link to buy it from China was dead.😢

[@spanishtreasure9551]

@@GloweIndustries tell you a secret , you can mix lead and lithium together no matter that the chinese or "professsional" engineers say and they do compliment each other keeping charge and voltage longer / stronger etc, but if you live in land structure , i would make sure batteries are in outside inside of brick enclosure area for fire prevention just for safety precaution, as lithium would be the one that could catch fire~ its a known fact . the chinese , others etc dont want people to know you can combine lead with lithium together, when you do this as many people with home boats have already done, lithium will do the work when not charging at night, and keep the lead up in voltage . Rule is always have more lead battery volume than lithium. if in a structure , i would also make sure batteries are in outside inside of brick enclosure area for fire prevention.

[@pandaturbo]

Such a good video, buddy. Everything was explained very clearly and with enough argumentation. You helped me a lot, thank you.

[@GloweIndustries]

no problem, glad it could help!

[@boatelectricaldiy]

I'm a marine professional and I won't install lifepo4 without it being directly in parallel with a lead acid battery. You are on the right track my friend.

[@Hammerback972]

Really? That’s what I’m struggling with. There are so many “pros” in car audio that will declare that if I use lithium and have an AGM battery (or 3 in my case) that the AGMs will kill the lithium off. I have a 500A isolator in place, and a 325A H.O. Hairpin alternator under the hood.

[@boatelectricaldiy]

@@Hammerback972 I have left a 300ah LiFePO4 hooked to a lead acid battery for months and the lead acid was full and the LiFePO4 was at 98%

[@GloweIndustries]

I've heard this from more than one person that works on boats, for sure.

[@nicholas8793]

Any thoughts about lithium being in parallel with the lead acid starter battery?

[@boatelectricaldiy]

@@nicholas8793 the only problem would be the alternator on the engine lighting on fire. I recommend the Wakespeed 500 to solve this problem for my customers.

[@harvmac69]

Great experiment! Thanks for showing!

[@GloweIndustries]

Thanks for watching!

[@seniorcarlos686]

Good job. 👍 answered many curiosity

[@GloweIndustries]

Thanks!

[@jamieharland9080]

Hello, I am happy I found this video as I installed a 48-volt 200 amp system with 2 banks of lithium separately connected to bus bars with a lead acid 48-volt 200 amp system also connected to the bus bar. I had this for over 15 months. I was thinking that if the lithium went flat it would use the backup lead acid setup. Still, I have had good luck with my off-grid never passing 50% state of discharge! My logic was lead acid likes being fully charged so I could not go wrong with being as neat as possible too with covered terminals and circuit breakers! Thanks for your time with the video

[@jeepjoe1996]

Very nice test!!

[@GloweIndustries]

Thank you!

[@SkillzZ4ya]

Thx man ppl will try to make u blow up ur subs n amps and batteries. U are the truth 🔊

[@GloweIndustries]

Appreciate it!

[@bigdaadio.K2WW]

Great video, A simple Hi-current, NO relay would keep the draw that we saw, at bay... (I'm referring to this setup in a vehicle, that would energize the relay on "key on") I'd be curious to see the results after, say a week or 2. Thanks for shedding some light on the subject!!

[@GloweIndustries]

I used to run an isolator, too.

[@milesmccarty1005]

I have been running a CG 208AH FLA bank along with a DIY LFP 150 AH bank for over 5 years now in my trailer. Does that count?

[@robertkosovich1232]

Interesting video, Thanks.

[@GloweIndustries]

You're welcome!

[@SVAdAstra]

I've been doing that for 5 years with no problems. I have a 100 AH Odyssey lead-acid battery in parallel with a 100 AH Battle Born lithium (LiFePO4) battery. The results of my measurements are exactly the same as in this video. The advantage is, lead-acid batteries are perfectly happy being stored at 100% state of charge, whereas lithium batteries age quicker when stored at a full state of charge. By connecting them in parallel and floating at 13.4 volts, the lead-acid battery is fully charged and the lithium battery is at about 80% state of charge. My climate never gets below freezing and I've disabled temperature compensation on my charger. One disadvantage could be a charger that uses lead-acid temperature compensation could produce too high a float voltage to keep the lithium battery below 80% state of charge in cold temperatures during storage. Also, one should never charge a lithium battery below freezing. My lithium battery has temperature sensing that disables charging below freezing. If your temperatures ever drop below freezing make sure yours does too. As reported by others here, the lithium battery does the bulk of the work and discharging of the lead-acid battery only starts once the lithium battery is substantially discharged at a voltage below 12.7 volts. This extends the life of the lead-acid battery. Recharging a lithium battery requires a really robust alternator as it will appear as nearly a dead short to the alternator when the battery is substantially discharged.

[@GloweIndustries]

Our cells are actually OK with being charged at temps as low as -20c. Discharge down to -30c. 💪

[@Hammerback972]

-20c? As an American, I’m gonna break away from the video and google that in “non genius Fahrenheit “😂 I’m back- that’s -4F for any other folks wondering.

[@Jim12291958]

Great video... thanks.

[@kennyrodg]

Thanks for this, just what I needed to see.... I'm UK based but have an American RV....I'm going to be upgrading to Lifepo4 in the next couple of weeks and this dispels a lot of my fears. We flat tow a car and use a brake buddy, the toad takes a 12v feed from our house batteries, I also have a voltage sensing relay from the house batteries to the RV starter battery to keep that topped up plus there's the aux start function to consider...I'll be upgrading the shore power charger to a lithium specific one and my solar charger can also charge lithium....I think i should be good to go then.....If anyone in the comments can advise me of anything else I need to think about I'd be very grateful... Thanks again for the video....

[@GloweIndustries]

No problem, happy to help!

[@LuisMedina-ef8pm]

Thanks for the experiment. I can see this only being a problem once the lead acid battery has degraded over time and doesn’t hold above 12v

[@GloweIndustries]

Yep - but at that point it’ll have the same effect on any battery, not just lithium.

[@evil17]

Good job mate, interesting results, I thought the draw would be a bit higher than that.

[@GloweIndustries]

I went into this thinking it would be higher, too… but honestly it makes sense with how little current a trickle charge uses to maintain a lead acid at 13s/14s.

[@ALEX-xd7ko]

I run an agm and lithium. My system sat for 10 days in -20° temps and was at 13.26v at day 10.

[@GloweIndustries]

That checks out with the test results I got, for sure.

[@drpc98014]

I just got a 100 ah lfp battery for a ups install. I still have the old but still useable 200 ah sla battery. don't really need the added run time but thought I'd explore using both. thanks for the info.

[@BenMitro]

I've setup two 100AH AGM with a 75AH LiFePO4 all in parallel. Its only been setup now for a couple of months but are doing very well. Runs a water pump.

[@GloweIndustries]

Should last you a long time to come. The lifepo4 holding the bank at a higher voltage is similar to float charging the lead acid batteries which drastically extends their lifespan.

[@alanblyde8502]

Exactly what I’m about to do, we have 2440ah @ 48 volts lead acid 2 volt cells, they float at 54v, will be hooking up a 100ah 16s lithium rack jaki battery, at this stage our lead bank is on 98% SOC after night, my plan is to let the jaki battery fully charge back up in the morning and auto disconnect it with a contactor so day time lead takes the bulk load and reconnect it before sunset so they are on same voltages. Leads should be at 100% float all the time

[@philbrooke-little7082]

I've been doing this for over 3 years and it works really well and means I haven't needed to fork out on expensive "lithium charging" equipment. I do use a BMS on the lithium that cuts off at 14v which at common charge rates gets it to 99%+ full, this avoids stressing it by holding the voltage at a full charge level which is one of the 2 things that Lithium doesn't like and which would happen if charging from an alternator. You also don't want to let them float on a lead acid battery charger as 13.8v will still overcharge them once full. The 14v disconnect and 13.5v reconnect ensures that this doesn't happen.

[@MegaCyrik]

You can not overcharge atleast lfp at CV CC. The battery simply stops accepting charge until you raise voltage. So you can float charge a lfp for 29 years if you like, nothing will happen besides normal aging. Its a nice feature i use daily. Current just drops to zero. I use 14v as well on my batteries but they stop themselves at 14v without any futher action. Edit: so dont worry about 13,8v "overcharging"

[@philbrooke-little7082]

@@MegaCyrik I strongly suggest you do some more research, the current doesn’t drop to zero it drops to close to zero, that tiny little bit that isn’t zero is what is doing the damage. This is what destroyed mastervolt’s early lfp batteries prematurely, it is why cell manufacturers tell you to terminate the charge and not to float them. If you must float them then it needs to be at a voltage at which they will take no charge ie below their full resting voltage which would be around 13.2-13.3v. The people who would be likely to tell you it is ok would be battery suppliers rather than cell manufacturers as they stand to gain from the deterioration of batteries. It doesn’t happen over night just as positive grid corrosion on lead acid batteries from overcharging doesn’t but it greatly accelerates calendar ageing.

[@MegaCyrik]

@@philbrooke-little7082 i have not been able to detect any current with my 5bit meter. Please send me a link to the topic at hand that you say has been proven to work differently. That should be interesting reading. Thanks.

[@philbrooke-little7082]

@@MegaCyrik look up the charging spec for LiFePO4 cells from manufacturers such as EVE, look up the lithium charging profiles of chargers. As an example the EVE standard full charge for capacity testing is 3.65v until current

[@MegaCyrik]

@@philbrooke-little7082 i couldnt find any specific about damage with float. I did read a paper on floating for up to 180days at 3,65 pr cell which was just silly. Didn't do as much damage as cycling, and it were a lithium but not lfp so meh. The search do generate unreadable amount of documents. Ill look out for any concrete data should i find some. Also yes i do recall andy testing float in hus chanel and coming to same result that you cant float a lfp. Anyway, usually it at max a few hours a day i use it at 14,00 and have not seen any problems. As sun is getting low the batteries are drained until sun is up again. im not going to look up anything related to charging or debate if lfp wants to be held at 3,65. I think that's on you. Seems you are moving the goal post of the topic, not sure if that's on purpose. And no im not going to hit my breaker on the mppt because you have a charger that's smart enough to turn off by it self when its job is done. I got a bucket of those. They are not special lol.

[@MegaCyrik]

About to replace my 5*12v 32ah SLA with 32650 lfp in my small EV. I put the SLA on my table and ran a capacity test. They are high drain for lead acid at 0,3C so i kinda like them. Anyway. They really hold strong at full capacity. So i wondered why not add them to my lifepo solar bank. Ofc, need a breaker.. IF there is a faulth the lifepo will dump 77 tera amps into that lead acid before i realise anything, so.. yea.. i dont like explosions inside lol. Might put a breaker between each single of them. But got off track now.. i ment to say f yea nice vid thanks.. stay safe and stay away from bud light! :D

[@GloweIndustries]

In a lot of marine applications the designer will include a small lead acid battery along with the lifepo banks. The benefit is two fold. 1. Lead acid batteries last a lot longer if they’re float/trickle charged constantly. 2. LifePo4 cells last a lot longer if they’re not idle at full capacity. Adding the lead acid will help skim off that surface charge after a good charging session.

[@g1egz]

77 tera amps, seriously, ? I wouldn’t want to be anywhere near your battery bank , if that’s the amperage you got running?

[@elcaminosupersport]

Good informative video. If drive vehicle dally shouldn't matter. Only if storing vehicle for a long time id disconnect any battery type.

[@GloweIndustries]

If storing for a long time.. best to put the lead acid on a trickle charger/maintainer, and to leave the LifePo4 disconnected. They can hold their charge for over a year and still be over 80% capacity. That said - do be careful about that. A lot of LifePo4 batteries have internal balancers that discharge the cells more rapidly than they'd normally self-discharge.

[@Contact_Info]

Thanks

[@GloweIndustries]

No problem

[@douglundy5755]

Yep, I have FLA and AGM with Lithium of 250 ah in parallel, they charge up to 14.4 and drop together to about 12 volts till recharging with solar or generator. The AGM really takes a lot of charging but its a great cranking battery for starting diesel engine. The Lithium keep making power for hours to run refrigeration and support the system voltage. They act, one guy says, like a capacitor to hold a larger reserve charge. It works. Theory comes from practice.

[@GloweIndustries]

I won't say exactly like a capacitor, but I get the comparison for sure.

[@slickwillybudgetking]

Great information 💁‍♀️ 👍 Now begs the question: Under a 150a or 200a load, does the system default to the LA ability (weakest link theory) or is it a minimal percentage drop from the Li performance? In other words, often it is stated with certainty an isolator is necessary when having two batteries of significant power (amperage) difference. Maybe it's not.

[@GloweIndustries]

I think that it takes so little amperage to float charge a lead acid batteries in the low 13s it won’t make much diff.

[@GloweIndustries]

Actually the higher voltage will supply the power first.

[@evil17]

@@GloweIndustriesThat is correct, & it will share the load, ie: if u have a 100A lifepo4 & a 100A LA connected to an inverter in parallel & it is drawing 100A, the lifepo4 will take the bulk of this initially (say to 80%-90%) & as the voltage lowers u will see the draw from the lithium lower while the LA battery amp draw increases. At 12v a lifepo4 battery SOC is around 95%+ depleted. You can see this if u run a shunt from each battery to an inverter and apply a decent load.

[@rustycezar7532]

hi , great vid, can i do this to my gel type lead acid battery (400ahx2 in series)24v and add up a 24v 100ah Lithium LiFePo4 battery in parallel ? i want to add the power of lithium to sustain a load current at high discharge rate in my system. Will this give more current draw that i need? or will it only follow the current draw of a lead acid? Thanks , im new to this.

[@GloweIndustries]

gel type doesn't change the voltage per cell, and they behave very similarly to a standard lead acid as far as likes and dislikes - this should be fine.

[@herbertcharles8606]

When you join two batteries like this would you take the post from the lithium and the negative from the lead acid to your inverter connections or reverse to this.

[@GloweIndustries]

As long as the batteries are in parallel it shouldn’t matter too much with solid connections.

[@paulkoski8759]

Do you have you own line of led lighting or whos and i like the the meter in the grill how did you do it and cant wait to get the series 2 think it will be perfect for my rp4500 and 2 x12s plus leds heated pwer seats gonna be running a sundown scv7500 soon should i get 2 batteries???

[@GloweIndustries]

Yes we have our own brand of lighting and make all of the stuff you see. www.gloweleds.com

[@austingoergen3837]

I plan to add an xs power battery to use for my sub amp and my stock agm battery for my mid amp will this work if wired like this. Was also thinking why not just run a distribution block from + of alternator( 1 lead for each battery)

[@GloweIndustries]

Send it. As far as adding the XS, though.. You should really consider a glowe voltage. We have a few comparison videos posted, and we've dested a D3400 with lackluster results.

[@adamrussell4703]

Lead acid and lithium have a good symbiotic working relationship the lithium keeps the lead acid charged, but don’t hope for more than 13.2 volts. This is plenty for my needs.

[@jamieharland9080]

I found that to be true and it saves the life of the lithium not being fully charged for too long

[@GloweIndustries]

Yep. Extends the life of both the lithium and the lead acid both.

[@scrappydont2478]

I see the Problem . You can design any test to produce what ever results you want . What I have found is after the Charging stops the batteries balance themselves out . It may take overnight but after a while 20 batteries will act as one large battery . I just found out Not all inverters are the same so one may not work in your system but a different manufacturer will . It may all be in the inverter people use when testing these systems .

[@GloweIndustries]

Oh.

[@PVflying]

Is the lead acid battery you tested with SLA or AGM type? This may affect the results as what’s true for AGM doesn’t necessarily hold for SLA.

[@GloweIndustries]

It's SLA - but AGM *is* lead acid as well.

[@douglundy5755]

I have AGM in my system and it slows charging BC AGM take lots of charge time. Then they output more power. It still works fine. I never discharge below 12 volts

[@checkitoutguy3155]

I have a 48v 100ah (5kw) LFP Battery and a 48v 200ah (10kw) Sealed Lead Acid battery bank (4 x 12v 200ah) connected in parallel to my 10kw charger / inverter. They were connected when their voltages were the same. They charge and discharge in unison and their voltages remain identical (to within 0.01v / 0.02v) throughout. The battery low voltage disconnect cut-off is 48v, so c.10% for the LFP and c.48% for the SLA. The LFP charge voltage is 58.4v, the manufacturer's suggested SLA charge voltage is 58.8v - 60.00v. It seems to work ok and I have not noted any abnormal signs, the only thing is that the SLA batteries are charged to c.53.2v when at rest, when the suggested level is 52v, so I guess that will impact the SLA bank over time ?, but in the meantime, it means I can use them with my LFP battery and get another 5kw of usable battery capacity, otherwise they would just be sitting there doing nothing.

[@GloweIndustries]

Yep, I haven't found a downside yet, honestly.

[@checkitoutguy3155]

Thank you for demonstrating the results in your video, this information helps people make a transition from SLA to LFP less financially daunting or indeed provides wider usage possibilities@@GloweIndustries

[@drpc98014]

Why don't you do a vid on ups conversion from sla to lfp? I'm digging out all my EE school books and working on a circuit that addresses over/under charge and discharge. would like to share my design with others and get their thoughts.

[@raducumilea-is2yi]

Hello! In sistems like 24 volts / 48... You know how they behave?

[@eagleray1]

Nice test, good to know. I suppose if there's no danger to the lithium, then the only potential danger is to the alternator. Also, I'd be very curious to see if a LiFePO4 battery of drastically different capacity shows similar results. Why buy a fancy multi-stage charger if you can just buy a tiny LiFePO4 to keep lead batteries topped up?

[@goddardwb]

I use the AC200P 25 amp 13.4 dc output. With the LiFeP3 parelled to the Trojans lead acid attached to the 13.4 dc.

[@GloweIndustries]

I agree.

[@evil17]

@@goddardwb does 13.4v actually charge a lithium battery to a full SOC? I believe u need 13.8v (3.45v/cell) to effectively charge a LifePo4 to a full SOC & start any balancing, as this is where it is just starting to climb up to the peak of its charging curve. I like to see my lifepo4 get to 13.8v-14v so I know they have got some balancing and a reasonable full SOC & then drop the voltage back to 13.4v to maintain this charge as the solar controller will take on any load that comes on at this stage & the battery will only be drawn from if the controller (PV array) doesn’t have enough power to supply the load.

[@junkerzn7312]

@@evil17 No, 13.4V will not. 13.4V to 13.5V is the float range. It will neither charge nor discharge LiFePO4. So if the lithium happens to already be charged, dropping to 13.4V will be fine and it won't discharge. But if the lithium is depleted, 13.4V will not charge it by much at all. You might get to 30% or 40% or something like that. Charging at 13.8V to 14V... that will take the battery to 100% SOC, but the end of the charging curve will curtail the current more than it needs to... particularly in colder weather. But there is another problem too. Lithium batteries have BMSs and have to balance their cells. They only generally do this above 3.50V/cell (14.0V). In fact, trying to balance the cells below 3.45V/cell usually results in unbalancing them rather than balancing them. So generally speaking if a LiFePO4 bank is not charged to 3.55V/cell (14.2V) and held there for 1-2 hours, the cells will eventually get way out of balance and cause problems. Many boat and RV owners fiddle with the charging parameters in the mistaken belief that they will improve the wear characteristics of their LiFePO4 batteries, charge to too low a voltage, and wind up wearing the batteries out faster instead of slower because individual cells are over-volting as they go out of balance (while the overall pack voltage is left deceptively low). It takes months of improper charging, usually, for this to happen. But for RVs and boats, you can't count on a full charge every cycle anyway so really that 1-2 hours of absorption hold is mandatory for those times when you are able to. It won't really hurt the battery, even full daily cycling to 14.2V. And doubly so in RV and boat setups.

[@ShaneS071]

Hi there Did you try cycling the batteries while connected in parallel

[@GloweIndustries]

Many people run them like this daily.

[@goddardwb]

I use my AC200P Bluette 13.4 dc output to charge my T105 Trojan parallel to my Wieze lithium. This has worked fine for our trailer. Any suggestion?

[@GloweIndustries]

If it’s not broken, don’t fix it? Does the 13.4 charge actually get it up to 100%? That’s only 3.3v per cell. But, come to think of it.. my battery once fully charged does drop to at least close to that level.. I’d be more comfortable with at least 3.4vpc before calling the battery fully charged.

[@bigdaadio.K2WW]

Is 13.4 enough voltage to properly float the Trojan FLA batts?

[@goddardwb]

The Trojans call for float of 13.5 so I've found 13.4 ok The LiFeP3 at 13.4 are about 99% so OK for me.

[@valmikabeneteau7229]

if you charge the whole bank with an alternator will running the lead acid in parallel save you alternator diodes when the BMS shuts down?

[@GloweIndustries]

Folks using our stuff in their car generally don't run a BMS, but in the situation you described yes - having a lead acid battery not behind the BMS would make sure that if your BMS did disconnect the battery that there was still a battery present for the alternator.

[@drpc98014]

what if you add a float charger running 24x7 to the mix?

[@thomasmaurer1097]

1 comment about your test - Flooded Pd, has the Lowest Resting voltage of any Pd-type.. (12.8-ish New), were an AGM would have 13volts- and an HO-agm generally has 13.35volts -Matching most Lifepo4 resting voltage (see discharge curve of Lifepo4 - it's a Flat-curve like Nihm/cd "holds 80%-ish of its energy at 13.3-ish, with less than 10% under 12.6 "cut-out should be 12v" .. ) pd batteries have a slope discharge curve - but a lower IR (higher CCA/ca) - so for any major spikes (burst loads like Subwoofers) the AGM - takes the Majority of the Load, -but its voltage drops faster r- when it hits the Lifepo4, the continues energy is now being discharged by the lithium - letting the AGM stay at FULL-voltage waiting for them Burst loads that lithium sucks at. Note - there are not many manufacturers that make Ho-AGM's, and none of the Major brands make these cells (rainbow-tops,ever start,die-hard,energizer,) , - there are positives and Negitves to Ho-agm, they are built more like a Deep-cell than they are a starting battery - designed for a continues output (high continues),, - but there life-span (in years) and cycle life (solfacation) is generally Less - lowest life-span of any of the Pd-types these are mostly used in automotive Racing (no alternators in race-cars if possible - drag-racers/ 5 lap races /small engine-etc) .. note Many conterfit batterys claim to be Ho-AGM.. i dont think any Chinese manufacturer makes them (I could be wrong?) my favorite manufacture is MM, the Mighty-Vipers "mad in Vietnam" .. . XS also relabels good quality batteries as-well for example they do not disclose their supplier's

[@GloweIndustries]

Thanks for the input! I’ve never seen an agm that can handle an amperage load like the stuff we’ve recently started selling. Our “Series 2” battery is capable of discharging at over 600 amps (2-3 second bursts or 535 amps (long 30s burst) while maintaining over 12 volts. 💪 Should check them out!

[@thomasmaurer1097]

i most cerntly will have a look im supper-watting a Ho-agm, i dont think your selling them, because you would Know if you were, these are not sold to general public normally , most people in Marketing / sells have no idea about the advantments in PD-batterys , just Lithum this, lithum that, not taking into considerations of Climet-temptures, or CCa-to-MASS, that Pd stomps all other battery types, - Ho-agms have a down-side - Maximum life time in Years is less, and have $-to-watt is just as high as Nihm/cd the Mass-and surface area directly relates to its ability to raidate the heat from the IR, = an agm can outperform a lithum for certain applications - but "advanced Pd (aka HO-agm) batterys are vary- hard to find , only a few manufactures make these puppies, the Us-military is the larges customer, and you have to buy them bulk to get ahold one - or a Surplue store , that will come afew-years old non-maintaind.. (find these in Manpads and different contrers for - bomb-removing drones ) some are designed for a Huge surface charge (like a supper-capacitor) and some are built for a Deep-cell applications , being able to deep-disscharge under 20% without damage and will parshal charge for a lot longer time - equaling Lithum's cycle life doing so .. these cells are labeled with "advanced Lead carbon AGM" Nano-Carbon AGM (VRLA) from C&D Technologies -- VARTA AGM technology also make a Ho-cell .. @@GloweIndustries

[@nzdatsports9659]

before i watch this , ill just say yes you can i've been doing it now for three years .no issue .

[@GloweIndustries]

My data will back up your experience. 🫡

[@andrewbarnard667]

@@GloweIndustries does your data show what will happen when the lead acid fails with a shorted cell?

[@ranig2848]

Great video. Here’s another one - many people saying charging lithium with an alternator will damage the alternator since lithium can sustain more amps when charging than lead acid and alternator at low rpm can overheat. So, most people add a dc-to-dc charger between the alternator and the lithium battery to regulate the current. But, would it be possible to just use a 1/4 ohm power resistor. At max alternator produces ~14.4v and lithium usually bottoms out at ~10v. With basic math we get 4.4v/0.25=~17amp. This would limit load on the alternator. It will also avoid the “shock” to the alternator if/when BMS does the high voltage cutoff… Wdyt? Will that work? Or am I missing anything? (Granted, as max voltage delta it would waste ~60 watt but it’s easy to find resistors that are rated at 100w and as the voltage delta decreases so will the wasted wattage - so not great but not a disaster either)

[@GloweIndustries]

I’m going to be straight up with you - I’ve always let my alternator charge my lifepo4. I find that charging rates keep at a reasonable level as long as the lifepo4 isn’t deeply discharged. If it was, I definitely would charge it by driving my car not idling it for sure to keep the fans going. I know quite a few people who have removed the lead acid from their car (myself included) and haven’t had any issues at all. As far as charging too quickly or pulling too many amps? Pish posh. Having a lifepo4 with an IR of 2 miliohms isn’t any worse than having a pair of lead acid at 4 miliohms as far as the current/draw is concerned.

[@andrewbarnard667]

​@GloweIndustries there are numerous people doing this on narrow boats and have had alternators burn out. They tend to rev quite low. They solve the problem by using a longer lead from the alternator. So charging it slightly less efficient. But when the lifepo4 is quite low it can still put a very high load on the alternator for many hours.

[@cccmmm1234]

You could use a resistor but that will turn a unch of energy into heat. At 17A a quarter ohm resistor would be turn 17x17x0.25 = about 70W into wasted heat. A DC to DC converter should be over 90% efficient.

[@ranig2848]

@@cccmmm1234 that’s correct but most of the charging time the current would be around 8amp (14-12v/.25) so while it would still waste energy, it won’t be 70w, it would be closer to 16w. If you’re budget constrained or space constrained that might be worth it. Also possible to use a smaller resistance resistor just to ensure amps don’t spike. Also keep in mind that battery has internal resistance, which is not big but still something.

[@charlesmanning2266]

@@ranig2848 It certainly is an option and should be included in the mix. What works for one situation might not work for others. If you were space constrained then I would go with a DC to DC converter eg Victron. Dumping up to 70W through a heat sink requires some space.

[@gatgolf]

What happens when the starter motor draws 800 amps to start? Will it all come from the LA as if the LA was alone, or will it over draw from the LFP, potentially causing the BMS to shut it down?

[@GloweIndustries]

Most BMS will allow over current for a short time. For instance, I used a 200a BMS at one point and I could start my car (taking 330a) no problem. On some models you’ll need to adjust the short circuit cutoff time to allow for longer to start the car, since a sudden rush of current demand may be translated as a short by the BMS depending model. The current will likely come primarily from the lifepo since it has a higher resting voltage and current from the lead acid would only be relied upon once the load forced the lfp down to the lead acid’s level. Example, if your battery can provide 200a before falling to 12.7v, that 200a would come from the lifepo4, after that the lead acid would kick in. But the rates still won’t be even since it takes less load to pull the lead acid down, they’ll both begin providing the amperage they can while remaining in sync with the voltage from the second battery. If the motor takes 800a to start, I’d recommend one of the 500a-1000a BMS modules they have specifically for starter engines. In the car audio world it’s a moot point - BMS modules aren’t used, only balancers.

[@wendellkeresztyen7687]

Could I do this on my boat for my trolling motor? Currently I have 320ah of lead acid/agm. On the front of the boat I have two 6volt 210ah in series as well as a 100ah agm in the back compartment. Could I swap the 100ah agm for a 100ah lithium? How would charging change? I plug in the boat when not in use to a charger/maintainer.

[@GloweIndustries]

A LOT of folks are doing this combo for marine purposes, for sure.

[@thriveforbest3217]

Sir i need help 😊🙏 can i use just 6x45ah lithium cells and remove my AGM battery from the car audio? I running standard alternator too. can it work without issues?

[@GloweIndustries]

It really depends specifically on what lithium cells. If they're solar cells rated at only 1c, it's going to struggle to even start the vehicle.

[@jimmythebudgetbuilder7197]

The lithium batteries will not charge over what it’s resting at,when you cut the car off and the wet batt is at 13v and the lithium is at 13.8 (example) it will trickle charge the wet batt basically until they are even at whatever voltage it meets at

[@kylewest100]

What I’d like to do is is set my 100 AH 12v lifpo4 in my aux battery tray of my Silverado and tie it directly to the starter battery. I’d like to do this because it’s annoying to me when my turn signals are going and the lights dim etc etc. I’d eventually be installing a winch and other overlanding accessories like diesel heater and fridge. Probably get a decent inverter but mainly want to stick with 12v gear for simplicity. I’ll probably end up running a mppt and install it in the back and just run two leads upfront. Decisions decisions.

[@GloweIndustries]

Careful installing a lithium battery under the hood of your vehicle!! This is definitely not advised.

[@kylewest100]

@@GloweIndustries I ended up buying a litime 12v 100 ah and also bought a trolling motor box with accessory plugs. Would the bed be fine? Or I could lay it on its side and put it under my rear seat.

[@BobboNaught-YT]

thx for this experiment! It sounds like there is effectively no draw. You'll get worse with a bluetooth BMS, perhaps.

[@GloweIndustries]

Bluetooth BMS can definitely kill a battery over time, but most will cut themselves off before things get too dire.

[@BobboNaught-YT]

The next experiment I would try is if any imbalance occurs with light or heavy loads due to differences in internal resistance, but I don't expect it to make a difference - they're still in parallel.

[@GloweIndustries]

I’ve done this test. Almost all of the load is drawn from the lifepo4. In upwards of 90%. Basically, if it takes 10a of draw to take the lead acid down to 12.5v, and 150a to drop the lifepo4 to 12.5v, that’s the distro you’ll get applying a 160a load.

[@nicholas8793]

@@GloweIndustries what about starting an engine? Will the amp spike get pulled from the lead acid?

[@novafilters]

what type of shunt are you using,

[@GloweIndustries]

A WonVon Bluetooth 600a shunt. Can find them on Amazon for like $90.

[@carloscardoso1909]

I have a starting lead acid battery and a house lithium battery on my boat. Can these two battery have their grounds connected together ?

[@GloweIndustries]

Yes they can. If they're both connected to the same circuit, the grounds are already connected in one way or another. This is extremely common in marine situations, actually. Your lead acid battery will last much longer if hooked up to a LifePo4, since the LifePo4 will do the equivalent of trickle charge it worry-free for in many cases months at a time depending on the size of your lithium battery. To be specific, though, this video is in regards to a Lithium Iron Phosphate battery (3.2v per cell) setup. You say a house lithium battery - if it's a battery consists of 3.7v cells (14.4v nominal) then no, this would not be a good situation as they charge at different ideal voltages.

[@carloscardoso1909]

Thank you for the information!!! The battery I have is: LiFePO4 12V 50Ah Lithium Iron Phosphate Battery. I’m not looking to charge them together or even connect to positive just the negatives. And was wondering if this is safe.

[@michaelbouckley4455]

Another KZbin video by Emily & Clark’s Adventure “Best Way to Charge Lithium - Mix it with Lead” gives recommended charge voltages.

[@GloweIndustries]

I actually talked to Clark today for quite some time!

[@tim1299]

@@GloweIndustries He says to add a lead acid but goes on to say the charging rates were bad for the lithium. He confused the H out of me. I have a motorhome and am deciding whether to go with lithium for house battery. Just one 100 amp is all I need. His video he posted two months ago is the one I am referring to.

[@kylekaden7696]

So I can keep my main starting battery lead acid an then hook up a 32ah headway bank with no isloter without problems..?

[@GloweIndustries]

That’s what my tests shows, yessir.

[@freshbutplain1144]

Did you do it and how did it turn out?

[@hommerdalor6301]

Except if the lithium is fully discharged during the night, the lead acid battery will be overdischarged, and the engine will not start. Cheers.

[@GloweIndustries]

@@hommerdalor6301 what? Are you saying that.. if your batteries are dead they won’t start your car? Yes that’s true. How would your lithium become discharged without draining your lead acid in the first place, though? 🤔 This is no different than running a lead acid alone. Or a lithium alone. If they’re completely discharged they won’t start your car.

[@hommerdalor6301]

@@GloweIndustries 😂🤣 Also, even with an isolator, if the lithium is fully discharged, and the contact is made with the charged starting battery, when the engine is idleing, the alternator can’t produce much power, his tiny fan won’t cool it. Maybe the 8Ah cells will have no influence, 32Ah, not much, but 90Ah, or 280Ah will certainly need something to limit the charge current , and a protection system to diconnect the batteries if the starting voltage becomes too low. ;-)

[@robertdillon9989]

Now try and apply a load !

[@GloweIndustries]

The lithium battery provides nearly all the power initially since it's voltage is quite a bit higher throughout it's charge cycle.

[@krazzykiller1]

keeping the lithium at below 80% charge will extend itself cycle life by 35%. keeping the lead battery at 100% will extend itself cycle life by 100% i siet the studies dine by gm in the 1970s.

[@GloweIndustries]

Yes, so this is actually healthier for BOTH batteries.

[@Angel_xXx_76]

Please redo this test with an XS Power AGM...

[@GloweIndustries]

Send us one!

[@bullbutter9699]

GO BLUE !!!

[@GloweIndustries]

O-H!

[@immrnoidall]

The lifepo4 has a BMS in it and won't overcharge or discharge.

[@GloweIndustries]

Not in this video.

[@leetaves9143]

man just what a poor man order i like it

[@GloweIndustries]

Should order 3.

[@elcaminosupersport]

If people drive vehicle daily seems like it would be ok if parked for months at a time it would be better if batteries were disconnected. Seems to me I don't know

[@GloweIndustries]

That's pretty good advice. But you can't leave a lead acid battery sit for months at a time or it will be drained by the time you go to start your vehicle.

[@7071SydcHome]

@@GloweIndustries Batteries are like dogs - they need excise!! LOL

[@ramiroaka9]

I would add supercapacitors

[@StevenStGelais]

I think the solution here is just install a disconnect on the lithium so if the car wont be driven for more than a week, flip the disconnect

[@spanishtreasure9551]

tell you a secret , you can mix lead and lithium together no matter that the chinese or "professsional" engineers say and they do compliment each other keeping charge and voltage longer / stronger etc, but if you live in land structure , i would make sure batteries are in outside inside of brick enclosure area for fire prevention just for safety precaution, as lithium would be the one that could catch fire~ its a known fact . the chinese , others etc dont want people to know you can combine lead with lithium together, when you do this as many people with home boats have already done, lithium will do the work when not charging at night, and keep the lead up in voltage . Rule is always have more lead battery volume than lithium. if in a structure , i would also make sure batteries are in outside inside of brick enclosure area for fire prevention.

[@GloweIndustries]

I know a lot of folks using both, too.

[@1981dasimpson]

the real problem would be engine cranking and if that would damage the lithium

[@GloweIndustries]

Hmm. The cells we use are all high-discharge LifePo4, and have no issue at all starting up even beefy V8s.

[@toryrobinson5898]

So they can run together in a vehicle????

[@GloweIndustries]

Yessir.

[@toryrobinson5898]

@@GloweIndustries do I have to use a fuse link or something

[@nathanandnieldiaries2858]

How about if we are connecting two diff batteries with diff capacities.ex. 24v 250ah lifepo4 and 24v 150ah sla batteries in parallel? What will happen?

[@evil17]

@@nathanandnieldiaries2858 if the sla batteries are ok, the results will be similar, size doesn’t matter. Andy paralleled a 100a lfp battery with a 1a palo lfp & did charge & discharges with them together, his tests showed no matter how unevenly charged they were each battery would only charge or discharge proportionally.

[@curtchase3730]

A couple of things here. Yes, I agree with the results of the test, ok fine. I've done it myself. Discrepancies could occur if the lead/acid battery has aged and it's capacity is reduced. One or more cells create a high resistance short from aging. Now the L/A battery may become a parasitic draw much more than when new and fresh. The other thing is IF the Lithium battery is literally strapped to the L/A battery using heavy cables, like 1ga or lower, when the starter motor kicks in, the Lithium will output much more current than the L/A battery! If there is enough current draw from the starter, it "could" kick off the BMS protection OR blow the thing up. Yes, the lithium battery will pull a harder charge too. That's my 2 cents worth.

[@GloweIndustries]

I have personally replaced the lead acid in my vehicle and rely solely on lifepo4 cells, even to start my car. It works well, but you do have to use a BMS capable of 300a loads. In the 12v car audio market, most folks top balance the cells then rely on an active balancer and forego a BMS though.

[@curtchase3730]

@@GloweIndustries Thanks 4 info. Some things are still new to me. 300amp BMS? wow. Most standard import LiPo's don't go that high till you get to 300amp/hr or higher.

[@evil17]

@@GloweIndustries hey mate, what type of 300A BMS & vehicle do you have? Because I thought they might need more than a 300A BMS to start without tripping on OC. I have an old Toyota hj45 3.5ltr diesel that needs pre-heating. I tried my new 1000A Kings starter battery on recently & it wouldn’t start it, maybe I should have disconnected the battery & just hooked up the jumper on its own as the battery was fairly low, or I could have just got a dud Kings starter battery as they show them starting 5 x 4WD’s with batteries disconnected, a total of 19 starts on one charge, I thought was pretty impressive.

[@GloweIndustries]

@@evil17 It's rare to find anyone using a BMS for car audio purposes.. A lot of builds are pulling over 1,000 amps etc. Most use active balancing with LifePo4.

[@evil17]

@@GloweIndustries interesting, thanks for the info.

[@matthewwiemken7293]

Lithium is so cheap now for usable capacity you get. Not worth it anymore to supplement

[@GloweIndustries]

Agreed.

[@cccmmm1234]

Very interesting, but please be more precise in your usage of Amps and Amp hours. You seem to get those confused a lot.

[@GloweIndustries]

That comes from filming stoned I think.

[@2008guelo]

@@GloweIndustries😮😂

[@mikecolwell5387]

Only difference I would see is when both batteries are in an actual vehicle there's draw as soon as you hook them up so your lithium starting at 14.3v or whatever it was is more like 13.3 so then regulator battery pulls from the 13.3 then rests at like 12.5 which is another story

[@GloweIndustries]

Not sure I follow.

[@slickwillybudgetking]

There are indeed mountains of bull 💩 🤣

[@GloweIndustries]

Way too much.

[@jasonbroom7147]

Leaving them connected to one another isn't necessarily a concern, but they have different charge profiles and very different behavior as SOC and voltage drops. As you saw in the first part of your testing, the LFP battery was taking most of the current during the charge cycle. LFP batteries should not be trickle charged, while SLA/AGM definitely should be. Most importantly, an LFP battery can be left at 11.5 volts for weeks on end with little or no damage, but if you tried the same thing with any lead-acid battery, it's going to self-discharge even further and permanent damage will result. What you "can" do and what is prudent are often very different things. You proved you can do something that trained engineers have already explained is simply not a good idea. Why would you leave dissimilar battery types connected? What is the net benefit of doing so when it's very easy to follow the common guidance on this topic?

[@GloweIndustries]

Many trained professionals do this especially in marine applications. As you mentioned, LifePo4 doesn't like being all the way full, and lead acid likes being float charged. The LifePo4 literally used a very small amount of current to float charge the lead acid battery in the mid 13s while not using very much energy at all to do it.

[@jasonbroom7147]

@@GloweIndustries - What's the net advantage, though? I have a boat with an SLA for cranking and LFP (24v) for my trolling motor. I don't see any reason to connect them together, when it is quite easy and prudent to manage them separately. I guess it's different for a vessel you live in, like a larger boat or RV.

[@semperfiblackjack6062]

You lost credibility when you used red cables for negative and positive connections. While you made the connections correctly, the mixing of colors presents a poor demonstration and would, if done in a real insulation, would be a safety risk.

[@GloweIndustries]

If insulation color is mandatory for credibility in your book - you’d hate a whole lot of the cleanest installs I’ve ever seen that all use a single color (normally black) for *all* of the wires. 😉 That said - I can understand why someone so fascinated with crayons would be offended by the color choice, Hooah!

[@1over137]

"4 point Amp hours flowing through the shunt". is nonsense. You don't get it do you? Ohms law. 4 amps through X resistance = 13.39V. If you change the current or the restiance, guess what? The voltage changes. All you guys seem to handle the first iteration of ohms law, but never the second and the third order required. It matters.

[@PVflying]

It’s hard to discern what your point is, because your attitude is getting in the way. You could perhaps take another run at explaining your opinion when you’re feeling calmer? It seemed fairly clear from the video his test was to see what current flows between two fully charged batteries at rest, so I’m not sure why you think ohms law is relevant as for sure the voltage he’s referring to is not that across the (very low resistance) shunt but rather that appearing across the terminals of each battery.

[@1over137]

5 hours in. The LFP is at 13.30V. That's about 60% charged. You just drained it by 30+% in 5 hours while it was running nothing. Draw the circuit out. The batteries are current/voltage sources/sinks, they are also resistors and capacitors. The leads are resistors. So the full circuit is 2 batteries and a set of 4 resistors. There are at least 4 critical voltages to understand what is happening. Also, at one point he says, "We are matched out here." One meter says 13.48 the other meter says 13.4V. That is NOT matched. Not by nearly a volt. Using mickey mouse little meters and measure voltage in one or two places will not explain what is happening and why you are flatten the battery. For the next test, leave the Lithium alone. Leave both disconnected and measure their SoC 5 hours later. Then maybe you will see the point.... that this process has no point, it will literally just flatten both batteries eventually. The LA will pull the LFP down with it. Completely negating the point of having lithium. My original gasp was because even the terminology is completely wrong. I am a believe that anyone who can't use the terminology correctly is not worth listening to. Ah do not flow through shunts. Amps do. Batteries do not produce "watts per day", that's just as stupid.

[@GloweIndustries]

@@1over137 what are you talking about? The battery wasn’t even close to 30% drained. It literally had nearly full capacity after two days.

[@GloweIndustries]

@@1over137 what’s stupid is measuring a lifepo4’s SOC by its voltage. 🤷‍♂️ If I said amp hours flowing - I misspoke and am not a professional video creator. Sue me. I believe the point was clear that there was very minimal current flowing from one battery to the other over the duration, and as the lead acid battery floated higher / closer to the resting voltage of the lifepo4 battery - that current dropped substantially. You know, because exactly what you said. Ohms law. If I have a battery that’s 13.336v and a battery that is floating at 13.335v, the amount of current flowing from one to the other at a .001v variance is insignificant.

[@GloweIndustries]

Also, you state that 13.4 and 13.48 are nearly a volt difference. By most standards .08v is not nearly a full volt difference.

[@rss608]

DP moho. new alt is $250 for the cheapy and $500 for the high dollar unit. Combining flooded cell for start batt and lith for coach batt.... will the lith batt kill the alt by over heating it when charging when it is drawn down? Or do I need to install a "time out" device to prevent the overheating of the alt.

[@GloweIndustries]

As long as you’re driving the vehicle (higher rpm) in a situation where you’ve discharged the battery, in most cases you’ll be ok. It’s when folks turn the car on to idle and let it charge up a depleted battery that the alternator tends to get too hot. 💯