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

Can you float charge lithium batteries? Should you float charge lithium batteries? What are the best settings for your charge controllers? Will float charge destroy your cells?
I played around with a lot of solar charge controllers trying to understand and find the best absorption and float charge settings. It can be very confusing and it's a bit hard to fit this all in one video. Please let me know if you want to see more details about a specific setting and how this works out in reality. I will break this down and make a separate video about that then...
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[@John-xu3jk]

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

[@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

[@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.

[@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. 🙏🏼👍🏼

[@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!

[@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. 😁

[@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.

[@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!

[@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.

[@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.

[@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.

[@chrisdhutch]

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

[@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.

[@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 😊

[@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.

[@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.

[@SVAdAstra]

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

[@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.

[@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!

[@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.

[@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.

[@hedfuka8608]

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

[@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

[@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!

[@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.

[@thomasreynolds9713]

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

[@OffGridGarageAustralia]

You are welcome!

[@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.

[@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.

[@tjsmith3060]

Thank you simplified for us novices.

[@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

[@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.

[@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.

[@mflo1970]

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

[@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 .

[@jamest.5001]

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

[@BTKCuk]

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

[@CryptoNut82]

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

[@dig1035]

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

[@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.

[@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

[@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...

[@rendark419]

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

[@ayubshaikh9156]

Nice ,natural ,jovial experiment With valuable info …….

[@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"

[@bambino3162]

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

[@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.

[@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.

[@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..

[@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.

[@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.

[@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?

[@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.

[@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

[@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.

[@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).

[@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.

[@ihorkukharchuk]

Yeah! That is the explanation that I was looking for the last few hours! Thank you, good man.

[@OffGridGarageAustralia]

Thank you. LiFePO4 is a bit different to the good old lead acid batteries we had before...

[@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.

[@CotyCondry]

thank you, this was the info I was trying to find about what exactly float charge means

[@patrickvanneck]

Thank you for this very comprehensive explanation. It is very helpful in setting the right parameters for my new 16s2P liFePO4 battery bank. Nowhere else I could find such a good explanation.

[@stevefuchs5868]

I have 2 6volt golf carts at 12v and wanted to add 16s lifpo4 in series par 12 volt . so sounds like 12.4 trickle is ok am i getting this right thanks in advance

[@lawrencekucharek3775]

Most Lithium batteries use a BMS and it is really what controls the charge and discharge of the cells. As long as you don't run the voltage too high the BMS deals with everything. I have charged (in an emergency) with a car battery charger and it took the batteries to over voltage and the BMS simply turned off the battery. once i removed the charger the BMS simply waited a short time and then turned back on. My float setting is just pretty much a way to use the solar panels instead of the battery once they are charged when solar power is available

[@OffGridGarageAustralia]

Well, the BMS should not control the charge. The charge controller or charger controls the charging and if this fails for whatever reason, the BMS is there to protect the battery, like in your example above.

[@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.

[@bassman53]

Hi Andy, congratulations to your new LIFEPO-channel, I watch your channel in Germany, it´s not very hot here, we have Minus C° and snow. I`ve found a lot of information for handling with the cells and how to buy at alibaba, Thank you very much, and please...don´t kill the frog

[@Mr1999tora]

Video davvero bellissimo e molto interessante, ti ringrazio della spiegazione. Complimenti sei davvero molto preparato.

[@BackyardRacing1]

Excellent work, Thankyou 👍👍

[@marktheunitedstatescitezen185]

Another very good teaching ! Thanks for making a point we already know but we do not do well setting up !

[@davidoflight1313]

The frog is trying to get a word in edge-wise; wants to be a youtube star like you. Good content by the way too!

[@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.

[@1sailfast]

Very helpful. You explained this very well and now I’ll have a better understanding about my Victron controller settings. Thanks

[@01walef]

The issue is with semantics. For long time non usage you won't let the battery state leave on high SOC therefore the customer has the option to activate the float mode. Greetings from Cologne, Germany

[@leelandutube]

hi, can you clarify what you mean by this comment please? i have the problem of a weekend cabin that isn't in constant use, so i'd like to have a lower state of charge during non use periods, but full charge when i am using the cabin. is this possible or should you have two settings, high SoC for when you arrive, then low SoC for when you are leaving? i hope this makes sense:)

[@01walef]

I've the same usage profile with my RV. When the RV is in use I want fully charged batteries all the time to maximise my autarkie time frame and charge setting is set to 3.6 volts. The BMS kicks charging off at 3,65 volts. When the RV is not in use, solar charge contoller is set to 3,4 volts. Float mode. Absorption mode equals float mode. The basic rule should be 80% SOC for long term no battery in use Self discharging effect is negligible.

[@marioescalona1640]

Good info Sr. Just want to point out that float charge is not only for maintaining the charge in lead acid batteries, it is because they will damage if maintained at full voltage when trying to get them to their full capacity. You can keep lithium batteries at full capacity without an appreciable degradation. Thank you for all the test information you share with your videos.

[@judgedredd8876]

Actually, keeping a 12.8V nominal LiFePO4 battery at 100% or 14.4V will degrade and reduce its life cycles by half!

[@lckoolg622]

Correct - I left my lithium LIFEPO 120AMP battery at 13.2 resting voltage for 6 months and it registered at 13.2volts when I connected it to my Renogy Rover-30 controller

[@marcsherwin6101]

Very informative video, thanks!!! Now i can safely set my 48v batts to absorption 56v and float charge 56v on my deye hybrid inverter

[@OffGridGarageAustralia]

You can but you can also go lower. I have used 55.2V for absorption (30min) and 53.6V for floating now for a while. They work perfectly. There is really no need to keep the voltage that high. It only stresses the battery but doe not add any further capacity.

[@marcsherwin6101]

@@OffGridGarageAustralia i will try your settings, thanks for the info. Cheers mate

[@arranpritchard9004]

I got the same results in that increase the float voltage so the battery charges subsequent to the bulk charge whilst there is still daylight.

[@bobby1970]

Great info. It's the exact video I needed to watch. Very important to know this about float voltage. Thanks, man.

[@OffGridGarageAustralia]

No problem! Thank you.

[@stevewilson8267]

I just found your video. I was confused on this exact topic. Thank you much for educating me about the requirements of the lead acid and lithium batteries.

[@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".

[@muvirimig]

Thanks cleared some of the questions that I had .

[@OffGridGarageAustralia]

Glad it helped

[@nalaka.perera]

Very good explanation

[@OffGridGarageAustralia]

Thank you.

[@learningpower9437]

Very good explanation mate !!! .... I appreciate your effort ... it takes time and even nature must collaborate in these types of videos !!! Thanks!!! You have a new subscriber!!!

[@martinhansen9517]

Nice to see you got an victron. Great info and video

[@OffGridGarageAustralia]

Thanks 👍

[@milanswoboda5457]

The confusion that often appears comes from the "trickle charge" of the olden days which was an unregulated voltage with constant low current charge to counter the self discharge of LA battery chemistries and that would be bad for Li-Ion chemistry battery types (LPF, NMC, LCA,...etc.) since this would likely result into an overcharge voltage due to their very low self discharge rate. Modern 3 stage chargers normally use CC for Bulk and CV for both Absorption and Float thus should never exceed the "safe" voltages of Li-Ion as long as the voltage parameters for those 3 stages are within those limits. So I myself separate "trickle" as a CC with unregulated voltage whereas "float" as CV (regulated voltage) but many use trickle and float synonymously for CV float and I'm not going to fight windmills ;)

[@dantronics1682]

do you use a bms on your batteries?

[@ceeweedsl]

Agreed. So much confustion comes from adapting LA wisdom and charge parameters to a different chemistry.

[@mikenr]

Many thanks Andy! As always great, useful and understandable info 🙂👍🏼

[@OffGridGarageAustralia]

My pleasure, Mike!

[@mrhalfstep]

If one is talking about drop in replacement batteries, which are cells wired together in a case with a built-in battery management system, BMS, with temperature sensors and balance sensors, etc, they would surly be set up to interrupt charging if that 13.2 v or 13.4 v charge would damage the cells. They don't. No harm no foul. I also understand that with most drop- in replacements it is critical that you occasionally charge above 14.2v because that is the voltage at which the built-in BMS does its cell re-balancing procedure and that is required to maintain battery efficiency. 14.6 volts is usually the max voltage rating but some lead acid chargers have the Equalization mode that comes on periodically to apply voltage in excess of 15 volts to a lead acid battery. This makes the battery off gas which stirs up the electrolyte to prevent the chemicals getting stratified in each cell (a condition that doesn't happen in Lithium Ion) and to break the sulfates down in the plates (another condition that doesn't happen with Lithium Ion). The LiFePO4 drop in battery will have a over charge protection circuit in its BMS so this won't harm the battery cells but it will shut it down and sometimes require some sort of "wake up" procedure to turn the battery back on. For this reason it probably should be disabled if possible. I use my batteries to run emergency inverters and to power electric trolling motors on my boats and I hook them to a 45 amp camper/caravan charger/converter and just leave them a few hours until they stop drawing current, than I unhook them. The charger has an Equalize mode that I can't disable, but it comes on at some infrequent interval and my batteries are never connected long enough for that to kick in. When I want to get up to the 14.2 volts required to balance the cells, I simply push a button that forces on the "Boost" mode and the battery gets charged to 14.6 volts. How do you get your BMS to trigger its balancing feature with your charge controller set that low? Is low voltage balancing a feature of the BMS you used?

[@ceeweedsl]

I think that you are mistaking over voltage protection for overcharging protection. Almost but not the same. They say that if you hammer you LFE with 13.6 or above after it's fully charged then it will deteriorate the chemistry. The BMS (or most) does no manage this aspect, only the max voltage in.

[@SpeakerKevin]

Thank you for this. One more experiment that I won't have to perform!

[@OffGridGarageAustralia]

Thanks Kev.

[@sswwooppee]

Great information to have. Danke for clarification on this point!

[@OffGridGarageAustralia]

My pleasure!

[@mckenziekeith7434]

The only thing I would say is that if you are charging up to 3.65 V per cell, it may not be a good idea to float at that level for an extended period. Especially if you are using a shore power charger as opposed to a solar charger. Because you will "float" at a pretty high absorption voltage for along time. But the lower the absorption voltage, the less this matters. And solar chargers automatically because of the sun going down, give the batteries a break at night. So it is less of an issue. I think for shore power, a good question would be what should the long term float voltage be set to? 3.25 V/cell? 3.3? 3.4? Definitely not 3.65. And same question for cases where an alternator is charging the battery. It may be OK to go to absorption of 3.5 per cell, but you don't want to float at that level for, potentially, many hours per day.

[@georgeiredale9397]

Nice video but just to set something right , the Lead acid battery will only drop the voltage for a small amount of time once the charger is disconnected, this is very normal and is just the surface charge dropping down to the normal charged battery voltage, it won't continue dropping unless there is an electrical drain or load put on the battery. It can however continue dropping if the Lead acid battery is faulty. Just saying as it may help someone checking the voltages of a lead acid battery.

[@fratermus5502]

Deep cycle lead-acid batteries have published self-discharge rates. They are typically stated in "per month" terms.

[@QUADBOYification]

I understand it all. Only wonder if passthrough solar power is wasted if the controller waits for a load to pull voltage below Float 12v. There is a dilemma here, do I use the sun to let the controller pass that power through to the load and leave the battery charging off. This is the ideal setting for most people if it were possible. If you have 800 Watt of solar panels in full sun there is no logical reason to charge an already fully charged battery pack or discharge it if the load is 400 Watt, right? Leave it sitting there and wait for the sun to dim or go behind clouds, then the ~800 Watt minus Load threshold should be breached and the battery kicks in. And after that the Float (Bulk) Charge. Nothing like this is available to buy today. It would basically be a UPS backup power system on Lithium-Ion batteries running on solar only. There are Micro-boards ($3) available on eBay specially designed to power 12v Routers and have them run uninterrupted if the 12v power adapter (8 amps max) from the mains fails. It is a completely electronic switch (No relais) using a Lithium-Ion 3S pack that should be integrated into 10-30A Solar Controllers by design.

[@PoncePappas-zo1ot]

I thought you were supposed to let your batteries discharge by using them until they reach a certain lower level and then they will automatically start charging again. From everything I’ve heard you don’t want these batteries to stay for all the time they are meant to be drained and recharged so what’s the real deal

[@amxmm]

Thanks a lot, that was very helpful. Didn't understand this stuff before.

[@OffGridGarageAustralia]

Thank you!

[@AnakinSpain]

what I understand in this video is in my case. I have a motorhome then I want that my LiFePO4 stay always at 100% so, I need to configure is : absortion and float 14.2v and then I have my battery ready for the night. Is it true? thanks.... and god job!!!

[@jerrytalley802]

I also have a Gopower 190 watt panel on the camper, a 30 amp charge controller built in. My plan is to put 2 more 200 watt panels. It’s not an off grid situation, but trying to be able to use the microwave or run fans in cooler weather. These should even run my AC for 2 hours or so, enough to catch a nap in a rest area, etc. This video was very helpful, thanks

[@dudeleboski2692]

SO ANDY, What are the best parameters to charge our LIFEPo batteries? Some people say maintain between 20%-80%. Andy, please, what are your thoughts on this matter, for the best way to keep our batteries healthy for the longest period of time?

[@AnilMaurya-cb8bx]

Respected sir If you can ...please make a video that how can we get a maxmium life span of our lifepo4 battery ..... What should the dod and soc ❤❤❤

[@antoniodecrisci2369]

This is very interesting that you make float=absorption and not float your battery at a lower voltage like most other manufactures suggest in their charge controllers. Have you tried using Renogy charge controllers? Their default lithium parameter are what you are doing, in the it keeps boost=float after the batter gets charged to the charge voltage. I cannot float my lithium battery at a lower voltage when I do the custom user setting in my Rover, but, when boost=float, boost essentially has 0.00 amp going to the battery once the charge voltage is reached, so it is basically floating at boost voltage. Its strange that way, but I think Renogy has it right like that.

[@fratermus5502]

According to the documentation renogy controllers do not float in Li profile - they are"charge and stop". Hence the 0.00A current until they hit re-bulk.

[@dig1035]

Fascinating and say hello to the frog. He's a regular!

[@radusdirect]

Thanks for sharing this knowledge. It really helped clearing many doubts in my mind..

[@VascoCTR]

So based on this video, what setting should I use among this once this inverter/charger has no other option? 1) 14.0 - 13.7 2) 14.1 - 13.4 3) 14.6 - 13.7 4) 14.4 - 13.6 5) 14.4 - 13.8 6) 14.8 - 13.8 7) 15.1 - 13.6 Thank you!