Lithium Cells in Float Charge. Will it destroy your battery?

[@sharonpointon4929]

Thank you, thank you, thank you. From a women who lives in a caravan and knows nothing about LifePo4 batteries, this has really helped me to understand how they work. Good to know that they don't have to go into float. 😁

[@Salsadepr40]

This video may be from 3 Years ago, but today 2024 it still makes a lot of sense with my Victron Solar charger controlar. The battery charger sheet for Battle Born is accurate. The understanding of the charging and float different made it easier for me through this video to make the proper settings on my battery charger. Thank you for a great explanation. 🙏🏼👍🏼

[@junkerzn7312]

Just a side note, once you've charged a LiFePO4 (and I think other lithium types too) up, say up to 13.8V or 14.0V and then stop applying voltage, the battery voltage will actually drop down to around 13.6V fairly quickly (well, probably closer to 13.55V). It remains fully-charged, that's the just the natural stable voltage for 4 x fully charged cells. So don't be surprised if you charge the battery up higher that you see it drift back down to that voltage. It just doesn't take a whole lot of current for the voltage to almost instantly drop back to around 13.55V. It can happen fairly quickly (depending on the BMS's vampire draw) even if no load is attached. So, for absolutely definitely sure, never set the float voltage above around 13.55V... that will cause the charge controller to apply a little current quite often due to the battery wanting to return to its stable voltage... and that is bad for the battery. And, of course, as the battery ages, even 13.55V will cause a constant current. Hence you probably shouldn't set the float above 13.4V or so regardless... and lower values are even safer. Up to a point. Remember to use the discharge curve, NOT the charging curve, to figure out what float settings you want. This means that, in fact, if you charge the battery up to 100% and start discharging it with the float set to 13.4V, the battery will still remain at least 90% charged as the charge controller starts matching amps below 13.4V against the load. However, if you discharge the battery sufficiently and the charge controller does not go back into BULK mode, then the battery's charge level will probably sit at just below 90%. So, to figure out the worst case charge level for the battery, you want to look at the discharge curve and at the voltage point where the charge controller switches back into BULK charging mode. So lets say float is set to 13.20V and the charge controller flips back into BULK mode at 13.10V. Thus, 13.10V on the discharge curve is the worst case charge state that the battery will ever be left in... lets call it 50%. Definitely NOT ideal. -- This creates a conundrum. If you set the float TOO low, the worst case state of charge that the charge controller might leave the battery in will be too low. Things can get iffy below 13.2V, so my recommendation is that the float be set at roughly 13.4V in order to ensure that the charge controller goes into bulk at a reasonable voltage (say, 13.3V, depending on the charge controller). This way if the voltage only drops to 13.31V and the charge controller stays in FLOAT, the battery will still be at around an 80% state of charge. You can safely set the FLOAT voltage to anything under 13.55V for a new battery, but to deal with battery aging you should consider not setting it higher than 13.45V or so. If you want to be conservative, then use 13.3V or 13.35V. I would not recommend 13.2V for the float because that means the battery could be seriously discharged before the charge-controller decides to go back into BULK mode. The state of charge drops precipitously enough below 13.3V that you just can't depend on setting the float below that voltage. This is why the Victron's Float is set at 13.30V. Its a good conservative value that will deal with battery aging but isn't too low to cause the battery to be left in too-low a state of charge when it could be charging. Now Bulk and Absorption are a different matter. In order to charge the battery, voltages in excess of 13.6V are required. 14.0V is a typical target voltage for BULK. Absorption is basically irrelevant... so set the voltage to something inbetween Float and Bulk Target and then set the absorption time to 0. HOWEVER, on some (most?) Victrons, the Absorption *IS* the bulk target voltage. Therefore, you should set Absorption to 14.0V (for roughly 80% charge) and set the absorption time to 0. If the Bulk target (or Absorption, depending) on the Victron is set too low, and the battery is being charged up from a low state of charge, it will probably never reach even 50% charge before the charge controller decides it is done. Once LiFePO4 reaches the target voltage during charging (Bulk target of 14.0V or so for 80% charge), the charge is done. The battery will remain at 80% charge even as its voltage slowly drops back down to 13.55V, and the percent-charged during discharge will head south from there on down. When you are discharging the battery, you should refer to the discharging voltage curve and not the charging voltage curve. This target voltage is really what you are comfortable with. Most people use 14.0-14.2V. Use 14.6V only if you want to actually charge the battery to 100% (most people do not as this reduces the life of the battery). This is my understanding. -Matt

[@OffGridGarageAustralia]

Thanks so much Matt. These are the comments we need with good, easy to understand explanations and examples. Great. I have planned to set the absorption to around 3.35V-3.37V and the floating just a tiny bit lower. As there will be more batteries following in the future, I'm not planning to charge them to 100% on a regular base. Maybe once in a while to do a test or so but I try to keep them between 85-90%. The same at the bottom, going below 3.1V is almost pointless, there is almost no capacity left und voltage will decrease very quickly under 3V anyway.

[@junkerzn7312]

​@@OffGridGarageAustralia Yup. Maybe even slightly higher. The exact setting will depend on the device's voltage measurement error. This might be why identical settings in the two charge controllers you tested yielded different results. The voltage sensors used by charge controllers, BMSs, etc, particularly cheap ones, typically have around a +/- 1% error factor. So the settings on one charge controller verses another may not manage the battery to the same exact targets. 1% is massive. e.g. at 13.0V the error is +/- 0.13V. Very significant. Higher quality equipment might cut that error in half, and if really done properly the equipment will be factory-calibrated and the firmware will temperature-compensate readings to get the voltage sense error below 0.3%. The balance lead voltage sensors are usually a bit more accurate but even so we're still talking 0.5% or so (0.016V @ 3.35V). On a cheap BMS even these are probably only 1% accurate. They can still balance the cells because the same inaccurate circuit is typically round-robined across each pair of balance leads, so the error winds up being the same for each pair. But in terms of relying on absolute voltage readings, you need to take some care when dialing in settings. How to get a more exact voltage reading? Difficult. A typical Multi-meter is usually calibrated to 3.5 digits or so... roughly 0.5% accuracy. Getting higher accuracy gets expensive real quick. -- Hence why it is a good idea to do a real capacity test with your charge controller settings to make sure its doing what you want it to do. These are longer tests (I'm specifying for LiFePO4). (1) Discharge the battery to 50% or lower, charge it up with the charge controller, then do a full discharge capacity test to the low voltage cut-off. Record the resulting Wh. (2) Charge the battery up with the charge controller, then apply a current-limited 14.6V to the battery with a power supply (limit current to 0.5C) and watch it like a hawk until the current begins to drop off to see how much more the battery could have taken. Record the resulting Wh that was additionally charged. And from those two results you will know what the charge controller is actually charging the battery too. -Matt

[@junkerzn7312]

@@OffGridGarageAustralia One other thing to keep in mind is that there is a voltage barrier somewhere in the 3.35 to 3.40V range. If you are below the barrier, the battery will basically not charge much at all, as you noted in your reply. More importantly, if you are above the barrier for long enough, even slightly, the battery will eventually get to around 90% charge without further intervention (albeit with ever-dropping current). The key word is 'eventually'. If you set your charge target too low and the charge controller then cuts off the voltage the instant it hits that target you could easily end up with a battery that is only 20% charged. -- This is perfectly fine for a 'Float' voltage set below this value, e.g. to 3.3V for example (remember, the discharge curve is very different from the charge curve!). But it is NOT fine for a Bulk or Absorb voltage set below around 13.8V (3.45V per cell or so). Anything below a Bulk/Absorb of 13.8V (3.45V per cell) or so is going to give you inconsistent results with a charge controller. Your Bulk/Asborb really needs to be at least 13.8V to get any sort of consistent charge percentage on the battery. The reason is as stated above... its because you aren't holding the voltage there. The charge controller is immediately dropping the voltage once it hits that target. You can dial-in your Bulk/Absorp voltage. Between 13.8V (unknown but usually at least 50% charged) and 14.6V (95%+). 13.8V (3.45V/cell) - usually at least 50% but wiggles around a lot. (charge to target voltage and then stop). 14.0V (3.5V/cell) - usually around 70% charged. (charge to target voltage and then stop). 14.2V (3.55V/cell) - usually around 80% charged. (charge to target voltage and then stop). 14.4V (3.6V/cell) - usually around 90% charged. (charge to target voltage and then stop). To get to 100% charge requires holding a charging-level of voltage (typically 13.6V or higher) for a period of time before ending the charge. The battery will continue to charge up to 100% or close to it. Faster with higher voltages, slower with lower voltages. Basically until the Cell stops accepting current (goes below 0.1C in current draw). With a charge controller this can be accomplished by setting the Absorption time to some value larger than 0. Of course, most people do not want to charge a lithium battery to 100%. (And again for other readers, never set the Float voltage that the charge controller drops to above the cell's nominal voltage of 13.55V or so or you will over-charge the battery. 13.3V is still an excellent setting for Float). This is also why, when testing, you have to start with the cell fairly significantly discharged... discharge it 50% or more. If you do not discharge the battery prior to testing, your will get a false result from your charge controller bulk charge test. -Matt

[@OffGridGarageAustralia]

Matt, you're saying: "Anything below a Bulk/Absorb of 13.8V (3.45V per cell) or so is going to give you inconsistent results with a charge controller." But if I charge to say 3.4V only and have a long absorption time, this result should be fairly accurate and repeatable. I can set the Absorption time as well as a Tail Current in the Victron to end Absorption and switch to Float. So if either the Absorption time runs out OR the current goes under the Tail Current threshold the controller switches to Float. I've done this before and could observer that it won't take longer than ~1h (if the sun is out) to drop the current from 20A to under 1A at 3.4V CC charging. That would mean the cells have fully absorpt at this voltage of 3.4V. And I should be able to get back to this exact point with the next cycle.

[@junkerzn7312]

@@OffGridGarageAustralia At lower target voltages, the current drops off very quickly, even before the battery gets much above 50%. At 3.40V you could easily see the current drop off to close to zero with the battery only 50-70% full (its a very wide range). If you trickle-charged it forever at 3.40V the battery would eventually get up to probably around 90% full, but the problem is that the time required is completely indeterminate. So the issue with using 3.40V for you is that you could wind up leaving quite a bit of your solar array's power sitting on the table unused due to the current drop-off. Now the question is... how much? And the answer is I don't know because your charge-rate is already really low so you might actually be putting most of the array's power into the battery through a good chunk of the current drop-off. I just don't know the answer with regards to how much solar power you wind up wasting during the current drop-off period. You will need to determine just how much the state-of-charge shifts around with target settings that low. My expectation is that even with the low charge rate, 3.40V/cell target could result in a battery bank that shifts around between 50% and 75% of full at the point the charge controller thinks it is done, depending on starting conditions. I think you would probably get more deterministic results with a 3.45V/cell target. At least I, personally, would not use a target lower than that even if I were trickle-charging at an ultra-low C-rate. The other issue still remains as well... small differences between cells will get magnified around 3.40V due to the voltage/current curve around that voltage, resulting in more out-of-balance cells. Another reason to have your charging target be at least 3.45V. -Matt

[@John-xu3jk]

wow .... literally years of being confused and 20+ minutes clears all the fog !!! Thank you

[@dennisbosworth3665]

I am glad I found you, here on KZbin. I just am in the process of switching my solar system from lead acid to lithium and I am finding the charging algorithms to be completely confusing - that is, until I found your channel. Now, things are starting to make sense! Thank you for sharing your knowledge.

[@bimmerjones3266]

I have found your observations to be spot on, especially for EPEVER charge controllers, which many think are faulty, or don't work with Lithium batteries. Their default settings are way too high for LIFEPO4, and the gap between boost and float create the challenge exactly as you mentioned. Your video was the most informative and educational one I have seen, and rectified what I thought was an issue with my 3 different EPEVER Charge controllers in my off grid setup.

[@OffGridGarageAustralia]

Thanks a lot for sharing and your kind feedback. That is great that you could understand the problem and finally fix it.

[@fishhuntadventure]

I have had a persistent problem across various models of Epever charge controllers. When battery is at a near full charge with FLA batteries or anything above ~13.x Volts on my recent LiFePo batteries the charging suddenly ‘drops out’ to only a couple amps or so. In good sun it will not recover to ‘normal’ charging until the following morning (darkness having occurred overnight) OR if I happen to be home I can turn off the panels, turn them back on, and it immediately tracks mppt and begins charging at 25, 30, 38A or whatever the sun position can muster. This occurs and has occurred on a 3210AN, one older tracer 4210AN and a newer triron 4215AN, a 5415AN, and a 6420AN. This does not occur /has not occurred with my MPP Solar AIO hybrid, nor with my 30A P30L PWM controller. Only the Epevers. I was about to sell everything Epever but I am going to attempt again with 14.2 boost and float and see how it goes. Seems a bit ridiculous that these otherwise excellent mid-shelf products have not been able to work dependably. Others on forums report similar issues so I’m not alone and would love to solve this.

[@ididntknowthatsr6993]

Any update did you fin the problem

[@danstrayer111]

are you controlling the EP charging parameter with the MT 50 meter? Just getting into this EP brand, setting it up next week. Hope you can respond

[@Nadeeja94]

You're a life saver Andy. I just finished wiring up my DIY battery pack and solar inverter and was so confused on what to set for bulk and float charge values. There's no absorption option in my inverter and this is exactly what I needed. Its all working smooth as butter now. Thank you so much. Love from SL

[@LaBamba690]

Nice video. Lithium batteries have been around for decades now so there's no excuse for these charge controller companies not to have a lithium battery setting that ELIMINATES all the old lead acid terminology and just uses the correct lithium battery parameters. Then you could simply edit them per your particular lithium battery manufacturer's recommended settings. All this "float", "boost", and "bulk" stuff is useless and misleading.

[@fc436]

no. the terminology is still correct. only the electric physic is important to management of the battery. if you reason by terminology or name of algorithms, then you dond understand the basic of electricity, like ohm laws

[@sethje]

@@fc436 Nope, he is correct. Terms like float do not work with LFP so should be avoided. They only confuse things. If the voltage drops under the treshold then the charging should start.

[@ekeokoronkwo8357]

​@@sethjeThe battery can be floated but the question is at what voltage, this keeps the battery at its peak charge more so in a case where the battery is connected to a load. The battery could be floated without the battery really charging.

[@sethje]

@@ekeokoronkwo8357 floating is only usefull when a battery looses power by itself. Lfp does not do that (extremely little) . Floating thus only increases the chemical aging of the battery. So no floating!

[@JShmoe]

There is only charge and discharge to the appropriate voltages with LFP.

[@capecoaster69]

Thank you very much for addressing the setting parameters relative to the chemistry of the battery. That is the fundamental feature that need to be look at first ,before embarking on the charge/discharge of batteries.

[@steve82608]

Another great video. You explained it well. I tend to think of the float voltage as mainly keeping the cells at a pretty high state of charge, and allowing you to run loads off the solar power when you have good sun. As you said, if you use either no-float (my CC does provide a 2-stage with no-float) or a really low float, you are missing out on using the sun when you have it.

[@jeffbowers950]

Excellent video explaining why float shouldnt or cant be used with lithium. You made it more clear than my battery manufacturer and solar componant supplier, both of whom did ok but not as well as you. Thanks for the effort. Glad to see you escaped from that tiny box.

[@fratermus5502]

> explaining why float shouldnt or cant be used with lithium I'd say it explains that "float" for Pb and Li means different things, and the Vfloat setpoint is used for different purposes.

[@FloryJohann]

You took years of mysteries away in just a few minutes and showed how it is working.

[@OffGridGarageAustralia]

Thanks a lot for your feedback!

[@BeepingMad]

Thank you for posting this, I am running a 24v hybrid system and have set the back to recharge voltage at 25.5v and the float charge at 25.1v. I have learned so much from you. Thank you again for your good work.

[@Deiseboi]

I have set my victron controller to 13.40-13.30 as you pointed out...new to the world of solar...so i wont have to doing anything more now and stop worrying???...many thanks for such a simple explanation of how it all works.

[@lebogangmogashoa8817]

I've been struggling for 3 days with charger settings for my lithium battery. Found useless contradictory info all over the internet, until I stumbled on this video. Great advice. Looks like I have now set my charger correctly. Only if I had seen this video sooner

[@gregronan4592]

Same here , longer than 3 days

[@OffGridGarageAustralia]

Thanks a lot for your kind feedback, guys! Much appreciated. I felt the same when I started, reading through endless forums and found information which did not make much sense.

[@williamcarpenter8902]

The inconsistencies are astounding!

[@lifepolicy]

Now revisiting your video two years later: on my Victron the Lifepo settings are bulk 14,2V and float 13,5V. That makes perfect sense because like you said in another video the voltage from a fully charged battery drops to 13,5V after a while no matter what if you charge it with 14.2V or 13.8V (13.5 is 100% from my mfg's handbook). When the charger hits float, you must restart it to start a new cycle.

[@bathfun]

My goodness, I actually understand this now. Thank you. The frog is fast becoming a star!

[@XspeedXracerX]

Just created a new Playlist and named it "Solar". Your video is the only one there at this point in time. Thank you for the great content!

[@OffGridGarageAustralia]

Thank you.

[@spyke556]

Late to the party here, but here is a perspective you may have missed, and that is charge current... So I want my batteries to charge to 3.4V, however when I set my charger to this voltage as we approach this voltage the current in the battery will start to drop, eventually reaching 0A at 3.4V when the battery is fully charged. This will take a long time. So I set my boost charge to 13.8V so that I can make maximum use of available charging power and keep the current high even at the desired 13.4V. Yes it means I am "over charging" my batteries past my target for a few hours, but at least I charge as fast as possible. Then when we switch to float charge, my loads will bleed off the excess charge and we will then reach my desired 13.4V and solar will kick in an supply the load. This way I get my batteries charged as fast as I can to take advantage of available sun.

[@chasethames2845]

Whenever I’m reading anything regarding my solar system or in solar forums it’s Andy’s voice in my head and if it’s not for you then I’m sorry we can’t be friends 😊

[@genxgamerdad141]

Wow, glad YT recommended your video, this cleared up a lot. Recently on a forum where people adamantly said not to float Li batteries. Even a representative from a certain inverter/charger company said Li should not be floated. As a solar newbie, I was confused by this. Looks like Float for lead and Li are two different things entirely. My battery manufacture even recommends a float voltage for their Li batteries. I set my batteries up per my manufactures recommendation including float, and all seems fine.

[@J7-Steny]

And what floating voltage did they recommend olvs its full capacity!?

[@genxgamerdad141]

@@J7-Steny I have 48v EG4 LP4 batteries. From their spec sheet: Charging Voltage (Bulk/Absorb) 56.2V (+/- 0.2V) Float 54V (+/- 0.2V)

[@2hotscottpro]

So there not all the same it seems.Battle Borns Green Dragon says to shut off float.And bulk or absorb ,don’t remember because I can’t do it with this Jamboni mppt.Learning and will upgrade mppt.

[@Marc-vl7wp]

Thank you. Finally LIFEPO4 bulk and float settings make sense because my inverter has no Lithium battery selection but a user defined one instead which still has the Float setting required.

[@benediktschluter7313]

Best video I've seen on this topic.

[@mannyfragoza9652]

yes and simple enough for a dummy like me to understand.

[@farmerjhemp]

If you want to shorten the life of your battery follow his advice. Setting the float and absorption so close is foolish. It will cause charge microcycles and shorten the lifespan of the battery. You should really just stick with the preset settings of the victron. When the sun's out I might be getting 800 watts going. My voltage might be showing let's say 27v once a cloud rolls over it immediately drops to 26.5. this proves that the cells aren't really at 27 volts. Their actual voltage is much lower. So if I was having my absorption at 27 volts I might only be utilizing 50% of my potential capacity. I might as well just go buy some lead acid batteries if I'm going to only use 50%. What is this guy trying to leave his cells to his great-grandchildren?

[@mannyfragoza9652]

@@farmerjhemp yeah we will have to wait and see 10- 15 years from now. Im not going to hold my breath lol

[@Sparklift]

Hands down best explanation

[@frankdg7090]

Many Thanks Andy....I Use a 100/30 MPPT Victron Smart and I only set the absorption-time for my 180A Lifepo4 to max 1 hour (instead of the standard 2 hours) but the absorption remained up to 14,4v....13,6v is actually 99% SoC. With your video I will decrease the absorption to 13,5v....and see what it gives...We are cooking very often with a induction plate, using a Nespresso, water cooker and toaster...with a 2Kw inverter

[@OffGridGarageAustralia]

Thanks Frank. You have to play around a bit with these settings. 14.4V is definitely on the high side but start with 13.8V as absorption voltage and leave it there for 1h or if the current drops below 10%. That should get you 99.8% capacity. Float could then be 13.4V to keep the battery 100% filled without any stress. If you have loads running the SCC will supply the power at this stage if they can.

[@SVAdAstra]

Perfect demonstration. I've been using the same method for 3 years.

[@immrnoidall]

I'm not trying to brown nose here but, seriously, you should get some kind of kindness to humanity award, lol, for your educational generosity. Just this one video has a classroom size of 127 k so far. I believe when teaching, there is nothing better than real world lessons.

[@ElectricCarAustralia]

Well done Andy on explaining the differences using practical demonstrations. This stuff needs to be right otherwise people will wreck their solar/battery gear.

[@urbanbeeman5402]

I agree wholeheartedly. If anything if you have a minimal load the "float" could keep you topped of at a very low charging rate...... Good job. I've been watching some of your videos for awhile but today you get a subscription.

[@OffGridGarageAustralia]

Thank you very much and welcome aboard!

[@solarute5486]

Good video mate :-) I have run my offgrid LFP bank (nearly 8 years ) in pretty much the same way. There is some research suggesting that the "mini" charges that the "float" setting does detracts from the cycle life more than if you could do one or two top up charges per day. So if the Charge controller, after bulk ("Top Up") charge cycle, could just supply make up current so the battery was not getting discharged - (but at the same time not charging the battery). .Then either at a lower threshold voltage or time (3PM in Brisbane) , the "Top Up" cycle could recommence. This will be the way I'll do it in the next incarnation of my system.

[@kareldelvoye8928]

Your video is what I needed. I use a Rebelcell outdoorbox 12.50 AV (Lithium-ion). Ask Rebelcell what setting to use to charge it with a solar panel, they didn't answer and all I could find was to use absorption not higher than 12.6V. The Victron controller 75 | 15 is set to Absorption 12.6V and Float to 12.3V and after your video I know I did the right thing.

[@ceeweedsl]

Most LFP mfr suggests 14.2 absorption. 13.3-6 float.

[@AveRage_Joe]

Excellent explanation and visual on a subject that many dont understand.💥🤘

[@jogo9996]

I have 2 new battle born batteries..i had it by mistake on agm. For a month it float charged a number of times..did i hurt my batteries..it's on the right setting now.. thank you...

[@kuhrd]

What you are talking about is not really self-discharge. You are talking about the surface charge going away which is a product of battery internal resistance. A fully charged flooded lead-acid battery is fully charged at 12.8V and some AGM Lead Acid batteries are fully charged at 13.0V. So the float voltage for most charge controllers will be slightly above that to keep the voltage high enough to prevent sulphation while also keeping the voltage low enough to reduce water loss. Most quality lead-acid batteries will lose about 5% per month due to self-discharge. So a 280Ah FLA or AGM battery will have a self-discharge rate of about 20mA @ 12.8-13V. When you charge most lithium chemistries they will still have a small amount of surface charge but they have lower internal resistance and also a lower self-discharge rate at about 0.5-2% per month. The self-discharge rate of your 280Ah cells will be about 2-8mA. Your lithium batteries will still draw power to match their self-discharge rate at whatever voltage you charge them to but your meter is likely not accurate enough to show the current at that rate. The reason you don't float charge your lithium batteries with the same settings as lead-acid is that the charge curves are different enough that you can use a differential instead and prevent the lithium battery from staying at a high charge state when you are trying to get the maximum number of cycles out of the cells. You typically try to cycle most lithium battery chemistries between 10% and 90% state of charge to get the maximum cycle life while also taking into account the trade-off with calendar aging.

[@OffGridGarageAustralia]

Thanks for your great explanation.

[@kuhrd]

@@bobby1970 Can you point me to a credible source that states that doing a discharge down to 10% capacity even one time will irreversibly damage the cells? Every cell type and manufacturer generally quotes their charge cycle life at 100% DoD to 70%-80% capacity. So a typical NMC cell can do 300-1000 cycles at 100% DoD. A typical LiFePO4 cell is can do 1500-2500 cycles at 100% DoD. The only reason people stay in the middle 80% of the capacity (so between 10% and 90% SoC) is that the cycle life improves enough to hit the sweet spot between calendar aging and cycle life while still having most of the capacity. Staying between 90% and 10% SoC will generally net you 4000-6000 cycles to 80% original capacity (this varies a bit between manufacturers, batches and battery chemistries). This is 11 to 16 years of service being cycled once each day in a typical solar installation use. Most of the information available states the calendar life of LiFePO4 cells to be around 10-15 years. The point here is that these cells will degrade at a specific rate over time even if they are being stored on a shelf at a storage charge for their entire life.

[@veryinteresting591]

@@bobby1970 : You are referring to Lead acid chemistry, NOT LiFePo4. LiFePo4 can discharge 100%.

[@dannyhaining4080]

Watching the younger kid demonstrating charge cycles, he was saying you can get beyond 10,000 cycles if you stay between 75% down to 35%. That is over 30 years. Now, I understand conditions would have to be most ideal ..like temp of the battery and ambient temps which can minimize battery life but damn.. that is j credible. Even this fellow is bulking to about 75%. For me.. with 1450 watts solar tied into my Victron 150/100 charge controller. Theoretically , I can charge back to 75% or 13.4 volts using solar, then use solar on whatever I’m discharging, unless it exceeds that 1450 watts.. then at night discharge three 300 Ah batteries to the 40-50% only to bring it back up to my set high end parameter at 13.4 volts or 75% of maximum. Right now, I am running eight 125 Trojans six volts set in four pairs. I have a residential fridge too. This winter, I’ll sell my 8 batteries.. which are in excellent shape and two years old, go to three monster lithium batteries and call it a life.

[@brucew4726]

I appreciate that this video is 2 years old. Thank you for this video; it is very informative. Sterling Power supply a Battery to Battery (B2B) 12 DC charger which I have in my van. My Sterling BB1260 also has a setting for Lithium. For LifePO4 lithium batteries, their default charging presets are; Bulk/Absorption 14.4v, condition13.8v and float 13.8v. They also default to Min abs of 30 mins and max abs of 30 mins. The maximum I draw from my 105amph lead acid battery is 15amp a working day. I was thinking about buying a replacement lithium as my current battery has lost capacity as it's nearly 3 years old.

[@OffGridGarageAustralia]

Can you adjust the settings on this B2B charger? I would lower them a bit, they are a quite on the high site. You can easily have 13.8V as Bulk/Absorption and 13.4V as Float. This will keep the battery 100% charged at a lower voltage level and is stress free for the battery

[@brucew4726]

@@OffGridGarageAustralia Thank you for the reply. Yes I can adjust those settings. It's a lot more complicated than the victron b2b charger as there is no app. Your experience over the past few years is very helpful. My BB1260 is rated at 60amp which is too high for a 100amph lithium battery, but there is also provision to reduce that to 30 amp. Thanks again.

[@kingjnr2677]

Hi Andy, wish I had came across your video earlier. I just finished my first campervan power distribution build and found out during testing the cheaper BCDC charges all have the same issue you have explained in your video e.g no float charge. Therefore losing the top part of your battery capacity. Not a major issue but definitely something ill take into consideration for future builds. Thanks for taking the time to explain everything, I will definitely be looking at buying a more expensive BCDC charger for future builds with a float charge / setting as to primarily cover the connected loads when charging power is available.

[@PowerPaulAu]

I've found 13.4v dropped my capacity down to about 70% (that was only a single test though), but 13.5v actually gave me full capacity (albeit the charge rate tapered off a lot). So like you did, I've now set my Bulk/Absorption and Float charge voltages the same, so there's just one voltage. These batteries are so easy to charge, they're awesome! The only reason I would suggest people have separate Bulk and Float voltages, is when they're using a Cell Balancer board that triggers a load over a cell at a certain voltage. Charging up to a higher voltage in this case, gives the cells a top balance of sorts almost every full cycle.

[@fredio54]

Depending on which balance circuit style you're using you may never get the cells into a balanced state with this setup. The reason to go to 14.X Volts, aside from to get full capacity, is to trigger some types of balance circuits which are only active around full charge. Watch the Will Prowse interview with the Battleborn founder - they go over the different voltage levels and strategies in detail there including the ideal float voltage, which is nothing to do with lead acid floating but, nevertheless, still exists, as poorly articulated in this video about 8 times :-D

[@fredio54]

Doh, I should have clicked "Show more" before posting, you already knew that. :-D The other reason is full capacity proper, those last few percent.

[@PowerPaulAu]

@@fredio54 perhaps you should watch more of Andy's videos before you go suggesting he's wrong or poorly articulated. He goes into a lot of detail and does a lot of real world testing. He's shown how well the system balances and it's more than adequate. Will Prowse has even commented on some of Andy's videos (commendation style comments at that).

[@fredio54]

@@PowerPaulAu Yes, I'm aware that his articulation skills are worse than his cell/solar knowledge :-D Kinda hard to watch for me, but not the point of my comment. I was pointing out to YOU something you already knew, that was hidden from me because of your longer post and youtube's standard behaviour. "Read more" is easy to miss. Nonetheless that Will Battleborn interview was a good one. :-)

[@PowerPaulAu]

@@fredio54 if it's hard to watch, then don't watch, and don't comment. You didn't add anything of value to the comments. Especially as you neglected to do your own research about this channel and its maker before commenting.

[@Springwood_Auto_Elect]

Well done Andy , these setting need to be correct and to be setup for each appreciation to maximise battery SOC selected , as a discharge will always be there as add components (inverters, fridge, online monitors) are consuming power at different times and condition. Cheers

[@OffGridGarageAustralia]

I need to do more testing once the whole system is setup to confirm all this. From what I could experience so far, this seems to work the best.

[@alexakis.st37]

I like watching u. Its like watching myself in my system in Greece. Every measurements i make always telling me stay victron. My batteries also are lifepo4 victron. I don't have the courage not even to take another brand in batteries

[@devonvankraft]

I also have the Victron MPPT and i love it. I hope this company wil make a serious balancer WITH leds AND software... smart system 👍👍👍

[@habana7638]

That would be nice indeed, I spoke with Victron about that but there are no plans for that, it would make the whole Lithium story with Victron equipment a lot easier

[@devonvankraft]

@@habana7638 okidoki.. yes exactly it wil make it way easyer.. it falls out of their warranty scope i guess.. too bad. Very good company tough. Al respek. Very much thanx for the Venus open source RPI project.. I hope there is more to come. A proud 12/1600/70 owner.

[@thedebrakuhn]

Wonderful timing on this video! Just received my 200ah LiFePo4 battery on 1/8/21 to replace four 100ah SLAs (moved to old Harbor Freight system for backup backup). Using Epever Tracer 40A CC with 500w of solar panels. Hope that I got CC settings correct because the com port of Epever CC just failed to connect to MT50 or eBox-wifi. Keep up the good work, very educational, enjoy your videos, watch almost every day.

[@donaldsteele6276]

Change the coms port channel for the mt50. That fixed mine .

[@HarmonyExpressSkoolie]

Very very interesting discussion on float charge. I would be very interested to see your experience with the EPEver Tracer AN. This is what I have for my Skoolie (School Bus RV conversion) and I'd love to know what to set my settings... Any advice would be welcomed!

[@aubreyj.tennant1123]

Me too!

[@view360deg]

WhAT an eye opener!! saved me few thousand precious Rupees for a Victron import, which we dont get in India :(. I will try same setting on my Systellar MPPT. Big Thank You!!

[@AnilMaurya-cb8bx]

I am also using in india Very deep information I found from this channel ❤❤

[@sergenalishiwa9097]

Most victron charge controllers are Made in India!

[@catch22frubert]

Very happy to see you got a Victron controller for your main battery bank. Its a quality piece of equipment that actually works like it should. Keep those beautiful cells safe, so you get many years of use. Love watching you test all the different electronics and cells. Looking forward to seeing everything set up and also looking forward to the solar gate project. Good luck!

[@OffGridGarageAustralia]

Thanks a lot. It is very exciting for me to test all this equipment and see what works and what does not so much.

[@catch22frubert]

@@OffGridGarageAustralia Testing is also my favorite part of the build. It just so much fun trying different configurations and figuring out the best combination for your needs. It makes for great content as well. Looking forward to the next videos.

[@TubeSkaterRudy]

Something remarkable happens with the Victron I observed which I actually liked very much. The Victron seems to charge only until floating voltage while there's a load present. Only after 0 load it's switching to the higher absorption voltage. I think that is a very interesting safety feature. Because when batteries are worn out they tend to have a much higher internal resistance. This difference in internal resistance gets much bigger because bad cells have lost capacity and are much earlier full. So with this one cell having a much higher resistance it could be potentially stressed out much more by a voltage overshoot when a heavy load suddenly stops but the charger stills compensates for that with a very high current until the BMS realized it needs to stop charging. So with this huge difference in internal resistance in some cells in these packs will make peak the voltage over this bad cells much higher and this cells will fail even sooner.

[@HansKeesom]

Isn't that just passthrough in the sense that if there is a certain load, the victron will allow for that same wattage to come in from the panels, leaving the battery connection in the same float process.

[@judgedredd8876]

The charger still pushes the absorption volt levels you set until the battery reaches that. But due to the load the reading is lower and it shows to be near the value of float. When the load goes away the voltage rises. Nothing to do with the Victron's program.

[@scantrain5007]

This was very helpful. Thanks for uploading! / Thumb up off course ...

[@OffGridGarageAustralia]

Thank you very much!

[@thomasreynolds9713]

Finally found a great video explaining float voltage on Lifepo batteries. Thank you.

[@OffGridGarageAustralia]

You are welcome!

[@rcinfla9017]

You are correct there is (and needs to be) very little continuous float current into Li-Ion battery at a given state of charge voltage. Li-Ion cells have no safe way to dissipate excess charging. Excess charging Li-Ion cells dissipates excess charge by detrimental electro-chemical side reactions, like breaking down electrolyte which is prime cause for bloating of cells. Trick is you want a float voltage that has almost no long term current pushed into battery and gets your desired amount of capacity on battery array. If you take float to 3.65v or higher you will see some signifcant continuous current pushed to battery that is detrimental for LFP battery long term longevity. You can go up to about 3.400v per cell and achieve an acceptably low continuous push current during float that will not be detrimental to cells. UPS continous float LFP battery systems typically set per cell float to 3.35v which gives 95% capacity capability to battery array. You have to allow some voltage tolerance margin for charger and cells balance matching which is why 3.35v is a safe number. 13.2v floating is too low for most folks as it gives you 3.300v per cell which represents an open circuit rested state of charge for LiFePO4 of close to 50% capacity. If you are comfortable living with 50% capacity available this is good for less stress on cells yielding longest longevity for cells.

[@dantronics1682]

wouldnt it be easier to use a battery bms

[@ceeweedsl]

Wow. I've been using LFE for some years and just started studying settings more to understand better. After tracking a few different YT thinkers on this, your few paragraphs manage to coordinate are relate some apparent conflicting ideas on float that this video did not quite clear up for me. Thanks! Your explanation now primary in my charging notebook. I'm gonna keep bulking at 14.2 because I need capacity and floating at 13.5 which Any led me to and you help me understand. I need all the sun power running my fridge etc that I can get but don't want to abuse the cells in the meantime.

[@ceeweedsl]

@@dantronics1682 A bms is not a substitute for charge controller parameters. It's protection against damage from extremes

[@BTKCuk]

Excellent work. There is a lack of correct information in this field so this video was very helpful.

[@georgedemean2228]

The frog is telling you "If you love your LiFePo4 Battery bank..Keep the Victron Controller" 🐸

[@TheWaterman1000]

Think one of his battery was croking out.

[@HansKeesom]

Always Victron, so much more quality, saving you money in the long run ;-)

[@bobby1970]

@@HansKeesom , no doubt, Victron seems to be the best. It's one of the few charge controllers that have Bluetooth. I just got my Victron controller, and I love it, especially with all those settings that I can customize.

[@copperknob1971]

@@HansKeesom have you tried to call them for technical advice ? Hopeless

[@HansKeesom]

@@copperknob1971 Technicall support for Victron products........... what are you talking about, you don't need technicall support for Victron products once you have a basic understanding of solar systems.

[@FloryJohann]

Man...that is very good information. I did not know how that worked with lead acid batteries and I did not not know how to set a simpler charge controller that does not has a lithium setting to the proper bulk and float voltage . Thank you.

[@MarkusIngalsuo]

You could use the absorption voltage to help the BMS balance the cells every day with solar and then float at a little higher than nominal. Since LiFePO4 has a flat voltage curve, balancing requires going closer to maximum voltage.

[@MarkusIngalsuo]

Also, love the frog.

[@wingerrrrrrrrr]

If you connected all the cells to each other in parallel and maintained them for an extended period at some mid point like 3.300V, would you consider them to be perfectly balanced? Or does the nature of the chemistry result in perfectly capacity-balanced cells possibly having slightly different voltages? Is mid balancing impractical just because of the difficulty of resolving the small voltage differences by the circuitry, or that they actually may have different voltage targets per cell?

[@MarkusIngalsuo]

@@wingerrrrrrrrr, they will eventually become balanced even at 3.2Vdc but it's easiest to just feed them 3.5Vdc for example until the current is more or less zero. The specsheet for these large cells do state to charge to 3.65 until 0.01C current or something and then stop charging. But, with a balancer or balancing BMS, just bringing the voltage of the series to above nominal will help the balancer do it's job because of the steeper voltage curve above nominal. If there is great imbalance, it will be hard for the balancer.

[@hedfuka8608]

Thanks Andy... I’m always informed and happy when I watch your videos.. 👍

[@sundancer442]

YES PLEASE DO AN EPEVER VIDEO WITH USING THE EXTERNAL GUAGE/CONTROLLER.

[@michaelbouckley4455]

As I read the info from Epever, the external controller cannot set Lithium

[@sundancer442]

@@michaelbouckley4455 It can, but you have to set the battery profile to " user" and then input the parameters manually.

[@james_mckey]

After listening to the first 3 minutes, I would like to point out some other differences. Charging or discharging a lead-acid battery involves a multi-step chemical reaction. Once a lead-acid cell has been charged, the secondary reactions will continue to happen, allowing current to continue flowing across the cell. This allows all the cells to reach their fully-charged state. These reactions are also somewhat self-limiting, producing heat through secondary reactions and increasing the internal resistance of the cell and reducing the amount of current as the cell charges. A lithium ion battery is a phase-change reaction where a lithium ion moves with the aid of the electrolyte between the cathode and the anode. Of the lithium chemistries, I'm most familiar with LiFePO4. The nominal voltage of 3.2v per cell is the point at which the phase change can occur. This is why LiFePO4 have such a stable discharge curve. You can think of it somewhat like boiling water. Whether the stove is on low or high, the pot itself will stay at a fairly stable temperature until nearly all the water has boiled off. When charging a cell, you need to apply at least enough voltage for the phase-change to occur. For LiFePO4 cells, this is at about 3.4v. Putting a voltage of 3.6v on the cell will allow the phase change to happen at the maximum rate -- which can be a problem if you aren't regulating the current going into the cell. Once the cell has charged, the phase-change is complete and no more current will flow. For this reason, a BMS system is very highly recommended for any lithium battery. A good BMS will allow current to continue flowing to each of the cells that are not yet fully charged, allowing all the cells to reach a fully charged state. If you're using a LiFePO4 as a drop-in replacement for a lead-acid battery, then float voltage is not really going to be much of an issue. A LiFePO4 "12v" battery has a max charge voltage of 14.6v. The phase-change point will be at 13.6v. Most lead-acid systems charge to 14.4v and float at 13.8v. This is close enough to the LiFePO4 specs that it should not be a major issue. With a proper BMS on the battery, then it should be no issue at all. I have a 12v 100Ah LiFePO4 battery backup system I built in 2010 or 2011 or so. The battery is held at float a majority of the time. I tested the capacity a few months back and it was still in the 90% range. This is NOT TRUE for other lithium chemistries! For example, lithium-nickle-cobalt will form dendrites if held at a float voltage. These dendrites will degrade the capacity and eventually short the anode to the cathode resulting in FIRE. tl;dr: LiFePO4 don't need to be held at float voltage, but they don't care if they are. Don't hold OTHER lithium battery types at a float voltage, though, or there could be fire.

[@GSCork]

Can't wait to see the EPEver video as I have the BN series and a 120Ah Lithium Iron Phosphate battery. New Subscriber :)

[@OffGridGarageAustralia]

Welcome aboard!

[@getfaith]

Andy your the best dude, i now have my settings correct for my mppsolar charge controller....thanks!

[@rendark419]

Victron, sehr gut! Hab hier den EPEver, warte aber noch auf meine Batterien.

[@j.k4825]

Good that you brought that up. Because of your video I took a second look into the way you charge lifepo4 and in the Inverter/battery charger combie I ordered, which is advertised for lifepo4. Turns out they use a IUoU charger which floats the battery constantly and would have ruined the lifepo4 cells over time...

[@dantronics1682]

if the cells are not absorbing any charging current since your battery pack have a bms then how would this ruin the battery?

[@jamest.5001]

There you are mid summer, and we are expecting a foot of snow tonight or tomorrow! Ha-ha!!

[@jimhanty8149]

I am working on this exact issue with my new Victron SCC. Your theory is perfect for a constant user of all available sun power…. One just needs to decide how high you want to keep it charged and then what voltage numbers to plug in so as to not waste the sunshine.. It would seem one would not not need a tail current enabled ( ? ) … or perhaps very low (1 amp) .. you didn’t state that …what do you say on the tail current if your ending abs at the same value of float.? "………BTW Great vid ,thanks..

[@hommerdalor6301]

Great way to explain. Thanks. The frog sound is better than any free music used in youtube videos. :) Chicken could bring some more rythme. :D

[@dig1035]

Just watched the new version of this but still had to watch this again! Different conclusions.

[@robertkosovich1232]

Nice job! Thanks for the information. I would like to see the epever in use if possible, waiting on batttery order to upgrade my system. Thanks again! Happy New Year!

[@robertkosovich1232]

@Glen Osborne I don't think so, never saw one.

[@mflo1970]

Correcto Andy la curva decreciente irá disminuyendo la corriente e intentado mantener la tensión para no sobrecargar la bateria

[@CryptoNut82]

Great video!! I love all my victron products, alittle pricey but they seem to just work and have great software to boot.

[@AussieAustrian]

Just watching this older video again. I’ve found that 14.2v (3.55v/cell) is a good charge voltage for LifePo4. Less that 1% difference @3.55v with less than 0.1A current than pushing to 3.65v/cell. But I like 13.8v as a float charge because this is the voltage where any imbalance in cells is noticeable and balancers can do their job. So floating @13.8v after a 14.2v charge gives all the time in the world for balancing to be effective.

[@b.morris2816]

I think keeping the same setting for bulk and float is a good way to go if you have a have some kind of load most of the time. I am not sure it would be good if you aren’t applying a load most of the time. This is something I have no clue about.

[@dantronics1682]

I use to think the idea of having solar was to power something and not just to charge the battery. wasnt the batteries there to fill in the gap when there is no solar?

[@ceeweedsl]

@@dantronics1682 For me, yes. Depends on if you have loads you need to power. If not, charge up and done.

[@JohnP58]

I wish I had this information before doing my campervan setup. Now it’s done correctly… with your help understanding this news way to go.

[@jamespayne8781]

If you have an active system with an inverter running 24/7 with intermittent loads like a fridge the idea of float could be revisited. It depends on your application as to whether float could be used.

[@XcarecaX]

How exactly would it differ? I ask because that is my case.

[@jamespayne8781]

@@XcarecaX the reason for float is to replace the charge in the battery as it falls below the set point. With a lead acid battery this mean the battery is fully charged when the sun goes down. Before I put my lithium batteries into service this seemed like a desirable feature. However I’ve found that the lithium batteries work a lot like a power tool battery. They are fully charged and then the charger is removed allowing the batteries to be used until they need to be charged again. I’m still running a refrigerator, separate freezer, water pump and several little chargers no problem. In a days time I use about one hundred amp hours of three hundred in the battery bank. This has actually worked out very well for me. I didn’t like the idea at first but now accept it as the proper way to use lithium. So…. I no longer see the benefit of trying to float the lithium batteries.

[@ceeweedsl]

@@jamespayne8781 That approach is good, but depends on having enough battery to pull it off and/or having a reliable charge source that won't go away. In my case my battery bank will only run my fridge for 2 days, even less in hot weather. So I don't want to be wasting sunshine and solar power just to optimize the abundant battery cycles. I need my panels to be powering my fridge and to end the day with a full-ish (not 100% unless it just got there) battery bank in case it's the last sun I'll see for a while.

[@jamespayne8781]

@@ceeweedsl I think most of us are still sorting out the truth about lithium cells and how to charge them and use them. There’s a lot of information and miss information on KZbin and the internet in general. I’m still looking into the idea of floating lifep04 batteries though I don’t really need to currently. I read on the Battle Born site that you can float them. There’s considerations though. One consideration is there needs to be a constant draw on them as in my original thinking. You wouldn’t want to float fully charged cells.

[@ceeweedsl]

@@jamespayne8781 Sounds right. I think the biggest take away in this video is that no current is actually entering the battery in float mode UNLESS it drops below Vfloat. So, one could say it's in float mode, but it's not actually getting any current into the battery, so it's more of a standby there to power loads. The undesirable part about floating is pushing current into the battery after it's been brought to full. But if the voltage is set low enough, there's zero to nominal actual current pushing into the cells. That's my understanding. What I'm trying to point out is that your cool power tool analogy/ approach is probably optimal IF you've got plenty of battery to spare and can afford to sacrifice storage capacity available at the end of the day. Then you can just charge to full, ignore any further sunshine and start draining. If your storage is closer to what you need to run things, then it's different and you need to make use of that sun to power things while it's out and save the most capacity possible for after dusk. I can't fit any more battery into my van! Gotta milk what I've got for what it's worth! Good to know that I'm not really abusing the cells to keep float at resting V.

[@rflulling]

I do a lot of work in building battery packs with LiION cells. Their nominal charge is 3.7V(14.8), but are considered 100% charge at 4.2V(16.8). Now if I take that battery off the charger and let or rest over night, in the morning, the charger will tell me the battery is now 96-98% so there will be a small discharge. Assumption is that if I left the batteries long enough they would rest at 3.7V Nominal. Sadly most small pack hardware based BMS do not offer any way to peak charge, balance, then let the cell rest until float/recharge only at sub nominal values. Instead they want to start immediately at any voltage less than peak, some even push past peak which may do damage. Guessing the unmarked controller uses the same kind of circuits that small packs BMS use, peak charge and balance only. I suspect that really Lead Acid are not that dissimilar, in that we over charge and then it drops back to a resting point, however like lithium if we keep trying to charge, it eventually damages the cells. I think Lead type cells are far more tolerant of this constant over charging. That their peak is something like 14.3-14.5 and Nominal is 12-13.5. However most of my recent experience has been with Lithium cells, and my car battery so, I can only claim opinion on the Lead acid and AGM side. Why use a BMS at all? Over charge protection, Discharge Protection, Cell Balance (many don't use but should).

[@peterrock2838]

Good information! I will set my two Epever 40A controllers accordingly. Another great video! I might get a Victron. I would like one or two 150V controllers.

[@OffGridGarageAustralia]

Thank you. I still have to try the Epever but al reviews are very positive.

[@ElectricCarAustralia]

Hi Peter, also look into Outback Power MPPT's. I have had 2 x 80 amp units running for over 10 years in the Qld summer with no problems. Oh except replaced a cooling fan in one.

[@peterrock2838]

@@ElectricCarAustralia Yes, I've heard great things about Outback. Thank you!

[@tibor304]

how to set the control parameters EPEVER? Which entries do I have to make for OverVoltDisconnect, OverVoltDeconnect, BoostChargingVolt, FloatChargingVolt, BoostReconChardVolt LowVoltReconnectVolt. I have 16s 3.2V 48V Lifepo4 200A = 10kW

[@chrisdhutch]

Thank you! This info worked just fine for me right here in sunny Jamaica🇯🇲

[@dirkverhoest936]

great work as this is the same system i need. can we see the frog ???

[@OffGridGarageAustralia]

Sure...

[@jeremygodoy4191]

This is hilarius in Chile because we have some viral video about "dirty frog"

[@georgesackinger2002]

Thanks again. I have built many solar systems with LiFeO4 batteries. It is nice to have a lithium setting but understanding the float settings helps in use of cheaper or just older charge controllers. Unfortunately, not all let me change this float voltage. Great information. I now know which controllers to upgrade. I also use mostly the Tracer series. They work fine for me and are much....cheaper than victron. I also like there higher solar voltage of 150vdc for the solar input.

[@AnilMaurya-cb8bx]

Respected sir I am using Exide nexcharge 100 ah. 48 volt 15 cell lifepo4 battery Please tell me charging voltage and float voltage ... ❤❤❤

[@OffGridGarageAustralia]

Thank you. For a 15s battery, set charging voltage to 51.75V (3.45V/cell) and float to 50.25V (3.35V per cell).

[@AnilMaurya-cb8bx]

Thanks a lot Respect to your deep knowledge .....very happy to subscribe your Chanel ❤❤

[@AnilMaurya-cb8bx]

Not sach a videos I found from indian you tuber ... .I told to many sellers but they unable to describe the charging stage .... But you clear all my confusion .... Thanks a lot sir ji ❤❤ ❤❤

[@AnilMaurya-cb8bx]

​​​@@OffGridGarageAustralia Sir Can we use thease setting for both ..as for The grid charging As well as for solar charging ???

[@Richi42]

​@@OffGridGarageAustraliadans la vidéo vous mettez la même tension, les cellules ne chargeront pas assez a 3,35, je ne comprends plus. Pourquoi ne pas tout mettre au même pour atteindre 3,45v/3,5v ?! À 3,35 elles ne sont pas assez chargées... 🤔🍺

[@whitepitohui]

Very clear now greetings from Holland

[@Amerona]

I have a more complex facility in a boat. There is also a alternator and sometimes a shore charger. I understand and agree with what you said about settings in MPPT. My problem is that when I run the engine for a while before I arrive in port, the BMS has turned off due to SOC = 100% and I have no charge at all from the solar panels. I then have to wait for SOC to go down to 95% where BMS reconnects charging. It usually does not happen until the sun has set and I then have a starting position for the night with -10Ah, SOC = 95% I want the alternator to charge as much as possible during the short moments I drive for the engine but still not get to SOC = 100% and BMS turned off charging. How should I achieve that? Change the BMS or change the charge from the alternator? Victron MPPT is set to 13.8 and 13.7V. I always have consumption in the form of refrigerators etc. so MPPT quickly restarts with BULK

[@judgedredd8876]

If your alternator is like a modern car's you are probably sending 14.4 to 15V to the LiFePO4 battery which is the upper limit or above. Most BMS will cutoff at least14.7V I am surprised the BMS does not disconnect from overvoltage.

[@judgedredd8876]

To force stop the charging at leas than 100% (14.4V) you must remove the cable from your alternator to the house battery and install a DC to DC charger. I use a KISAE DMT1250 and I set it at 13.4V so that's when charging from the alternator stops. I can also adjust the max. charging current in 5A incrememnts from 5-50A. Or get the Enerdrive 40+ which is the Australian version.

[@judgedredd8876]

Note that charging the LiFePO4 to 100% versus to only 75-80% reduces the battery's lifespan by almost half. 20%-80% SOC is the sweet spot.

[@Amerona]

@@judgedredd8876 Now days i have two DC/DC parallell. And BMS i set in ”critical mode” wich means it not turning of at SOC=100% as it used to do. Now it only turn off att critical states. DC/DC is tuned so all work well.

[@ceeweedsl]

@@judgedredd8876LFP has such good cycle life even at full cycle charge/discharge. For some, it's worth it to get 25% more capacity for 2500 cycles than have insufficient power but battery lasts 5000 cycles. Depends on usage, space etc.

[@shameelali2549]

Excellent video again,and so detailed,i think of the float setting as a trigger switch,i found similar to you that when the float is set to say 13.5v if that battery slowly gets discharged and gets close to that voltage it slowly trickles current in float mode to maitain 13.5v but if u do a fast discharge of say 10amps it will then start bulk charge mode again.

[@jws3925]

What % of battery capacity would you recommend for long term storage? I have heard 50% a fair amount of time but, interestingly, when I talked with Battle Born they told me they recommend fully charging their batteries for long term storage. So, what is one to do? I have an off grid cabin that is not used for months at a time and this is in a cold weather climate. You like to keep your batteries at 80% max charge it looks like. I assume this is for longevity of the battery. Mostly I have heard about preserving battery longevity one should stay between 10 and 90% of capacity. Are you just taking extra precaution or do you have data that might reveal 20 and 80% window for discharge is actually optimal?? Thanks for this and other videos. Very informative>

[@ahaveland]

Great explanation and demonstration! I think the PCM60x that Pete from HBPowerwall has can also float properly with lithium, and cope with a decent sized array. Seems the consensus now is that LiFePO₄ cells last longer if their rest state is 100% SoC, unlike LiCo and Lipo cells which age faster at the longer they are held at 100%.

[@OffGridGarageAustralia]

I don't know if they live longer at 100% but it certainly does not really hurt them as long as the voltage is not to high. Floating at 3,35V seems to be their natural rest voltage anyway, so we go with that.

[@johnhill3507]

Video very helpful Thanks

[@OffGridGarageAustralia]

Thanks a lot, John!

[@kc79ta]

Man, I wish I would have found this video sooner. You did a perfect job explaining, and demonstrating it. My Growatt 3000 inverter/charger all in one automatically sets the float charge the same as the bulk charge setting when you choose the lithium setting. Had me totally confused. Thank you for explaining why.

[@OffGridGarageAustralia]

Thanks a lot for your feedback.

[@sspence65]

Why does the battery voltage immediately drop on a lead-acid when removed from the charger? Because the resting voltage of a lead-acid is 12.7v, not 13.4v. It's not due to self-discharge (that will happen over time). The charging voltage is always higher than the resting voltage, otherwise, the battery will not charge.

[@awesomusmaximus3766]

True for every chemistry

[@MasterT2]

what is the resting voltage for lifepo4? is it 14.0v or 13.6v?

[@sspence65]

3.6v per cell, so 14.4v for a 4s battery.

[@sspence65]

More of an issue with lead acid as there is a higher differential between charge and resting voltages.

[@asterixtug]

I've just replaced the AGM bank with a lifepo4 bank and was wondering about the parameters of the DC-DC charger and couldn't find any sensible advice on what to do until I watched the videos and at least I think this is the solution. On my boat when underway the consumption is around 25A and I don't want to charge the batteries around 14.6V, however I would like the batteries to be around 80-90% SOC, so I believe your advice is the solution vs the charger's standard lifepo4 setting, at least I am experimenting with this. Thank you yours videos and greetings from Finland!

[@kareemucfi1936]

Thank you and god bless

[@SY-Yggdrasil]

Das war wirklich mal eine gute Erklärung! Da existieren doch einige Mythen. Und bei Physik hilft der Glaube einfach nicht weiter.

[@proudaussie3522]

I have question ...if a lithium battery has a certain number of charge cycles ..let's say 2000... would the constant "little charges" back up to maximum severely reduce your number of cycles and lessen battery life ?

[@andrewallen9993]

Check how well the lithium battery in your cell phone works after 700 cycles or two years :)

[@owenbruce4120]

There are good batteries and poor batteries, so battery quality will be the first criteria, however, a complete cycle is between two voltage thresholds so micro charging will have a lesser chemical effect and less degradation

[@ShitkidOfJamrock]

When a battery lists a cycle life of 2000 cycles, it usually means you can expect the battery to survive 2000 full cycles of the battery So if you discharge and charge it 10% a day, you complete 1 cycle in 10 days This doesn't take into account damage from overvolting, undervolting, or discharging in the cold or heat. So long as you keep your battery in its normal voltage and temperature, little charges shouldn't significantly impact cycle life count

[@Francoisdp82]

​@@andrewallen9993 the battery in your phone is not lifepo4.

[@davidleslie949]

I was wondering the same thing because I know on my Milwaukee M18 5 amp battery that's rated for 1000 minimum cycles. I spoke with a representative about lithium ion or cell phone batteries and he had stated that every time you charge a battery no matter what battery it is or what kind or how large or small that count as a charging cycle because you've discharged a little bit and recharged a little bit Which is technically a charging cycle.

[@bambino3162]

Love the way you explained it.Easy to understand and demonstrate it. Thanks

[@jmaus2k]

Just set all the same to float, bulk, equalization. The reason you need the bulk charge voltage higher is to charge leadacid batteries faster to compensate for their higher resistance. And equalizing is to overcharge a bit to get the lowest cells to come up to charge while boiling slowly the higher cells is only needed for leadacid. You really just want a constant voltage charge. And with solar you will probably want 3.65V for cell which you likely won't hit that everyday.(remember you should design battery capacity to be able to power your loads for 3-7 days without sun). You could even let your cells go to 4V for bulk. Then set 3.65V for float. Might help to keep cells equalized if you don't have a balancing bms that does that. And like you are thinking, if you don't need 100% of the capacity, just set all the voltages to hit 95% or lower to improve life.

[@PRASTRO]

For lithium you use the same voltage in all parameters bulk absorption and floating 👍🏻👍🏻👍🏻👍🏻

[@OffGridGarageAustralia]

This does not work with all controllers though I think. I'll try it out...

[@jimmurphy5355]

That is correct. LiFePO4 cells are full at 3.65 volts. 3.65x4=14.6 volts. It is absolutely OK to hold the charger at that voltage indefinitely. The current the battery will take at that voltage declines to almost exactly 0 amps. But if the charger backs off to 13.4 or so, that's OK too. The battery will lose almost no charge, and if it does drift down (which might take months) it will still be at ~98% full.

[@upnorthandpersonal]

@@jimmurphy5355 "It is absolutely OK to hold the charger at that voltage indefinitely." - This is not the case. A LiFePO4 battery kept at full charge all the time will sustain damage. Furthermore, when the battery is full you must disconnect the charger, because the battery voltage will then settle to around 3.5V - keeping it at 3.65 will cause damage, and you can actually overcharge. There are several resources you can find, e.g. from Nordkyn Design that show this. Normally you stop charging when the charge current reaches 5% to 10% of the Ah rating of the battery - if you cannot stop absorb based on current, you'd pick e.g. two hours, but then disconnect.

[@jimmurphy5355]

@@upnorthandpersonal Well, the battery I built is charged up by my solar charge controller to 3.65 volts per cell every day. And it holds there for a few hours until I use the battery in the evening. My usage runs it down to about 20-23% most days. The coulomb meter the monitors the charge has not shown any detectable reduction in capacity after the first 300 cycles. There was about a 2% reduction capacity in the first couple week, but nothing I can detect after that.

[@upnorthandpersonal]

@@jimmurphy5355 Holding it for a few hours and then cycling it back down to 20% daily is fine. Keeping it at 100% (or near) state of charge for prolonged periods of time is not. It's the same reason why for long term storage (months) you store LiFePO4 at ~50% state of charge. Even though I would still recommend not holding it at 3.65 for too long (normally based on current flow dropping to 5% to 10% of the Ah rating) for best cell cycle life.

[@peterwalker7869]

G'Day Andy. Just found your channel. Nice to find an 'no nonsense' channel with descent content. I can send you a few frogs to help out with the background chorus. I have plenty here. It started raining here in Townsville Christmas night and we have had some rain every day since, so our frogs are in heaven at the moment.

[@jeremygodoy4191]

Rename this channel: off-frog-garange

[@OffGridGarageAustralia]

Hahaha, they are here only if it rains though...

[@lindafoxwood78]

Great information! I just bought 2 sets of 8 LiFePO4 280A batteries. Set one is now 2 months old, set two is still on the way from China. I will check set one for swelling soon. My cycle rate so far has been: 75% charge and 25% discharge using a float charger. This video of yours is a topic I need to know more of. Thanks again.

[@OffGridGarageAustralia]

Thanks Linda, I have made more videos about charger settings for LiFePO4 cells and also continue to extend on this topic as we go and gain more experience. Also, watch the playlist when I tested the LFP cells with different settings. kzbin.info/aero/PLPomydD54sgC0pAzeOBz_-ZMfGMzJYYWK

[@leotheevinci]

Very helpful indeed! Next video should be about maximizing the lifespan of your lithium batteries by SOC and DOD.

[@OffGridGarageAustralia]

Voltage is the killer, not SOC. Keep the charge voltage low and the discharge voltage high. 3.1V-3.4V is perfect to use almost 95% of capacity.

[@leotheevinci]

@@OffGridGarageAustralia So even if the SOC is always at 100% (3.6v) it won't reduce the lifespan of my batteries? Isn't the voltage correlated to determine the State Of Charge? Example would be a 50-60% Depth of Discharge (3.0-3.1v) with maximum of 90% (3.4-3.5v) State of Charge would prolong the lifespan of Lifepo4 batteries.

[@TechieTard]

This was PERFECT for what I was looking for.

[@OffGridGarageAustralia]

Thank you. There is more about this topic in other videos I made.

[@amulocog]

I think the concept of float current as implemented by technology is to deliver float current only when the battery voltage is lower than the float voltage. This means if lifepo4 will not self-discharge below float voltage then float current will remain zero.

[@OffGridGarageAustralia]

That is absolutely correct. LFP will stay at 3.35V naturally and charging will turn off completely at this point.

[@harrymuurling2742]

Great explanation and very logic, that's why I did charged for a while with and buck stepdown converter and that's worked very well, I changed it with my mppt charger developed for lifepo4. more security but exactly the same result as the buck converter, only 2 milly amps different

[@OffGridGarageAustralia]

Yep, they pretty much work the same way.

[@mrhalfstep]

Sorry, this is such a long comment. I'm coming to believe that it's the only kind I know how to make.LOL My understanding has come to be that a Lithium Ion battery (LiFePO4 is just one of many Lithium Ion chemistries) will do fine on a charger with a float setting, for all the reasons that you point out in this video. The cells WILL self-discharge SOME over the course of a year, but very little and when they do they should be topped back up and that would happen automatically with a charger that had a float setting. You don't NEED it with lithium but it is not a bad thing to have available. The low self-discharge rate is one of the reasons they are so popular with RVers. They can let their campers/caravans sit anywhere over the off season with no need to have an AC power source or solar to keep the battery charged as they would with a lead acid battery. They can just top the battery off when they roll out next season and the battery is fine.

[@OffGridGarageAustralia]

Thank you, John.

[@barrydavies2977]

Great information. Thanks. Could this be why some people are complaining about their lithium batteries not charging? I have read various comments where people have said "used it once and it wouldn't charge".

[@BobboNaught-YT]

So cool, thank you! So basically it seems like all you have to do is ensure that the voltage doesn’t climb above the correct voltage.