LiFePO4 charging question

[dryfly]

There have been several threads on charging the LiFePO4 batteries with the standard LA battery chargers. It appears that around 80% SOC is the most that can be expected from these chargers. But, is there any way these chargers can damage the lithium batteries? Is the charging profile about the same?

The only issue I can think of is that the lithiums require periodic charging to 100% SOC to balance the cells, which obviously cannot be achieved with a LA battery charger. Other than that, any issues?

 

[coglesby]

I just bought a 100A lithium compatible converter for $180 on Amazon. I don’t think it’s worth taking a chance on those expensive batteries.

 

[Butcher]

Lithium batteries have a BMS and that is the gateway for the electrons to go in/out of them. Anything can happen, but as far as I am concerned, if everything is working as designed, no damage will be done.

People forget, it's the BMS that matters. A charger will not overcharge a lithium battery, it cannot, impossible. That's the BMS's job. I believe people keep thinking these are LA batteries, which have no way of preventing an overcharge [short of blowing up].

Although cell balance is important, I suspect the average person that has a lithium battery, knows nothing about them. Ignorance is bliss. Having a balanced battery just means that the charging and discharging will get the maximum capacity of the battery. I like knowing what goes on behind the curtain so I look at balancing numbers all the time. It's a disease I have with everything.

 

[dryfly]

Lithium batteries have a BMS and that is the gateway for the electrons to go in/out of them. Anything can happen, but as far as I am concerned, if everything is working as designed, no damage will be done.

People forget, it's the BMS that matters. A charger will not overcharge a lithium battery, it cannot, impossible. That's the BMS's job. I believe people keep thinking these are LA batteries, which have no way of preventing an overcharge [short of blowing up].

Although cell balance is important, I suspect the average person that has a lithium battery, knows nothing about them. Ignorance is bliss. Having a balanced battery just means that the charging and discharging will get the maximum capacity of the battery. I like knowing what goes on behind the curtain so I look at balancing numbers all the time. It's a disease I have with everything.

Well, that's what I was thinking. As long as the BMS is working there should be protection. My application with this 100ah battery is not for RV use, but I'll probably end up getting a dedicated small charger to try to get max capacity of the battery.

After further reading it does look like the charging cycle is different from the LA battery chargers, and this is apparently why you can't charge a lithium battery to full charge with a LA charger.

Sorry for your disease, but how are you monitoring the balancing numbers?

 

[Butcher]

I pull out my phone and look at the app. I have 4 JBD BMSs and use the Overkill app. They are programmed to balance and it does a fairly good job.

I read a lot of comments that a standard converter would only charge a lithium battery to 65%. I felt this was wrong and the more comments I read, the more I thought to myself, people are just parroting what others have said. Since I use my stock converter on car repairs now, I was able to hook this stock converter to a LifePo4 battery and I measured [using my Overkill app] that the battery was well over 80% charged. I cannot recall the exact percentage but I put the data somewhere on this forum.

Of course, I got people that did not believe me, but I really do not care. Test results trump opinions.

 

[reubenray]

Reading through this thread I want to make sure what to use with my LiTime LifePO4 battery. I currently have this. Will this work or not?

Amazon.com

 

[Butcher]

Anything from Amazon is not worth buying. Just my opinion. I do my best to support sellers that do not go through Amazon. I prefer local sellers so I know my neighbors have a job.

Lithium batteries do not need tenders. Tenders are for LA batteries. Again, my opinion.

I have a lithium battery in my house wall switch for my ceiling fan. It's been there 15+ years. Still works. I highly doubt if you will leave your RV sitting that long. I suspect it would take many many years for a lithium battery to self discharge. Yes, it would matter how much it was charged before you started.

There are plenty of different opinions on this. Nobody is wrong, just different. I think we can all agree not to leave a battery where it turned off and let it sit for years. Damage will occur.

 

[dryfly]

Reading through this thread I want to make sure what to use with my LiTime LifePO4 battery. I currently have this. Will this work or not?

Amazon.com

While the Battery Tender is a first class product, it is intended for LA batteries. As said above, trickle chargers are not recommended for lithium batteries. Lots of info on this available on the internet.

 

[reubenray]

While the Battery Tender is a first class product, it is intended for LA batteries. As said above, trickle chargers are not recommended for lithium batteries. Lots of info on this available on the internet.

What will be the best way to make sure my battery survives the winter? I have read just to disconnect the cable or remove the the battery to put in my garage? My battery is under an overhang on the tongue of my trailer which makes it hard to remove and reinstall. The main reason I changed to a lithium battery was my AGM was very heavy and hard to get out of the battery box. The lithium battery is lighter, but it is still hard to get out and put back in. I actually have to drop it back in.

 

[triplethreat]

What will be the best way to make sure my battery survives the winter? I have read just to disconnect the cable or remove the the battery to put in my garage? My battery is under an overhang on the tongue of my trailer which makes it hard to remove and reinstall. The main reason I changed to a lithium battery was my AGM was very heavy and hard to get out of the battery box. The lithium battery is lighter, but it is still hard to get out and put back in. I actually have to drop it back in.

I don't know how cold it normally gets where you live, but I'm in the Knoxville, TN area and we get into the single digits once in a while. Maybe not at all one winter, and then only a few days or so the next, but for the most part, not below zero.

So with my LiFePO battery, it stays in the camper. I have a 300A battery disconnect switch that totally takes the battery offline, except for the small milliamp draw from the BMS. When I winterize (usually in Nov.), I will get the battery SOC to between 50 to 55 percent SOC, turn that 300A disconnect off so there is no draw or any possibility of charging it. The battery is in the front compartment, next to the hydraulic stuff and the generator and temperatures in there are pretty much the same as outside air temperatures. So the battery just stays there all winter and slowly self discharges at a slow rate, plus the little bit of draw from the BMS. By the time that spring rolls around, I have gone from say 50% SOC (in Nov.) to mid to low 30% SOC in late March early April. I do check the SOC though throughout the winter, via the BMS app on my phone just to make sure that nothing unusual has happened. I built the battery in the spring of 2022, so it has been thru the winter of 2022, 2023, and is in storage now for 2024 winter storage.

If something way out of the ordinary for our area happened, like -15F was forecasted, I do have the battery inside a battery box that is insulated and heated that I could use to get through the crisis. I put it in for a "just in case" and have not had to use it yet <<<knock on wood>>>

 

[Scott'n'Wendy]

What will be the best way to make sure my battery survives the winter? I have read just to disconnect the cable or remove the the battery to put in my garage? My battery is under an overhang on the tongue of my trailer which makes it hard to remove and reinstall. The main reason I changed to a lithium battery was my AGM was very heavy and hard to get out of the battery box. The lithium battery is lighter, but it is still hard to get out and put back in. I actually have to drop it back in.

Depends where you live. But start with isolating the battery from loads. Then charge (or discharge) to the manufacturers instructions on storage. Battleborn recommends 100% charge for storage, everybody else recommends 50-70%. Don't know why the difference. After that leave it in the RV or garage till spring. Self discharge rate is pretty low with LiFePO4. Unless it gets really cold where you live like where I am. Commonly -20* occasionally down to -40*. In this case, some manufacturers say the battery case could crack...so mine go in the garage where it freezes, but not that cold.
If I lived by 'previously xrated' I would leave them in the RV.

@triplethreat Do you use some self regulating heat trace for your battery box?

 

[huntindog]

I pull out my phone and look at the app. I have 4 JBD BMSs and use the Overkill app. They are programmed to balance and it does a fairly good job.

I read a lot of comments that a standard converter would only charge a lithium battery to 65%. I felt this was wrong and the more comments I read, the more I thought to myself, people are just parroting what others have said. Since I use my stock converter on car repairs now, I was able to hook this stock converter to a LifePo4 battery and I measured [using my Overkill app] that the battery was well over 80% charged. I cannot recall the exact percentage but I put the data somewhere on this forum.

Of course, I got people that did not believe me, but I really do not care. Test results trump opinions.

The 65% orginated from several you tubers years ago.( IIRCC, the actual number was 62% and several came up with the same number)) They were boondockers, and that was their experience in a boondocking situation. With generator charging it makes little sense to run it after the converter drops out of bulk mode.

Given enough time, a stock converter will charge over 65%.

But unless one is on shore power, it just isn't practical to do it.

 

[triplethreat]

Depends where you live. But start with isolating the battery from loads. Then charge (or discharge) to the manufacturers instructions on storage. Battleborn recommends 100% charge for storage, everybody else recommends 50-70%. Don't know why the difference. After that leave it in the RV or garage till spring. Self discharge rate is pretty low with LiFePO4. Unless it gets really cold where you live like where I am. Commonly -20* occasionally down to -40*. In this case, some manufacturers say the battery case could crack...so mine go in the garage where it freezes, but not that cold.
If I lived by 'previously xrated' I would leave them in the RV.

@triplethreat Do you use some self regulating heat trace for your battery box?

I have a digital temperature controller that runs on 12VDC. It has it's own temperature probe and that is located in between two of the battery cells. I can set the controller to whatever temperature I want, for it to come on (within it range of operation) and when the probe senses the setpoint, it turns on and sends power to four 7 Watt, 12V heater pads that are inside of the insulated battery box that I built.

I have four of these....two on each side of the battery box...

Amazon.com

And this is what controls the heaters....

Amazon.com

If the battery temperature is below the 32°F, I make sure that my 300A battery switch is turned off so that no charging is possible (the BMS should also prevent that, but just in case), and then I can turn on the Converter/Charger to supply power to the Digital Temperature controller and the heating elements and let it start warming up. With the 300A battery disconnect turned off, the converter/charger cannot get power to the battery to charge it, even when the heaters have brought the battery temperature up to a safe charging temp.....I have to manually turn on the disconnect for charging to take place

I may try it out again sometime this winter if we are going to have a couple of days that the temperatures are in, say....the 20s or so. Not really wanting to charge the battery, just wanting to make sure that everything is still working like it is supposed to be and the way it was built and installed.

Temp controller is mounted in the Gray plastic box on the back wall of the front compartment.....the larger box on the left.....1st pic below.

Here is a pic of a couple of the heater pads inside the box....two of these on each side of the box, none on the ends of the box.....2nd pic below

 

[TimtheToolMan]

I pull out my phone and look at the app. I have 4 JBD BMSs and use the Overkill app. They are programmed to balance and it does a fairly good job.

I read a lot of comments that a standard converter would only charge a lithium battery to 65%. I felt this was wrong and the more comments I read, the more I thought to myself, people are just parroting what others have said. Since I use my stock converter on car repairs now, I was able to hook this stock converter to a LifePo4 battery and I measured [using my Overkill app] that the battery was well over 80% charged. I cannot recall the exact percentage but I put the data somewhere on this forum.

Of course, I got people that did not believe me, but I really do not care. Test results trump opinions.

Your results make sense to me and will depend on the converter. The WFCO, for example, (newer may have improved though) like to hang at 13.6 volts and not reduce to a proper 13.2V float (only claim to but don't with any load) for lead acid battery. It would take a very long time to fully or nearly fully charge LFP at 13.6V but it may do it. SOC vs Voltage Table

If the converter drops to 13.2V then lower numbers would be expected. So both results can be correct.

 

[TimtheToolMan]

Reading through this thread I want to make sure what to use with my LiTime LifePO4 battery. I currently have this. Will this work or not?

Amazon.com

No it will not work properly on LFP.

You may know that you can purchase a quality LFP compatible charger that will slowly charge for about the same price, but I can see that you are trying to use what you have. NOCO

If you have not done so already, you may want to follow LiTime instructions (not a recommendation), here are only some of them: recharging to 100% (14.4-14.6V) every three months (possibly to balance cells for maximum life) and store at 50%. Many/most will tell you three months is not needed but I will follow the guidelines for my LiTime at least for now, while being skeptical at the same time. I wish I knew where some manufacturers came up with this and the results if I did not follow...

Also, not to keep battery on a charger in storage...

 

[coglesby]

I have wf-9855 (no AD).

Just measured 13.68V at the converter and 13.22V at 600AH lifepo4 battery. Charging current was 7.2A.

 

[reubenray]

No it will not work properly on LFP.

You may know that you can purchase a quality LFP compatible charger that will slowly charge for about the same price, but I can see that you are trying to use what you have. NOCO

If you have not done so already, you may want to follow LiTime instructions (not a recommendation), here are only some of them: recharging to 100% (14.4-14.6V) every three months (possibly to balance cells for maximum life) and store at 50%. Many/most will tell you three months is not needed but I will follow the guidelines for my LiTime at least for now, while being skeptical at the same time. I wish I knew where some manufacturers came up with this and the results if I did not follow...

Also, not to keep battery on a charger in storage...

Right now my battery is being kept charged by my solar panels. Would I be able to turn off the solar panels and check on my trailer weekly to check on the battery level of SOC. If it gets to a certain level of SOC (?) could I turn the solar panels back on to charge the battery? My trailer is about 15 minutes away in a storage lot that gets full sun. So far the temperatures has only barely got into the upper 20's for a day or so. If I have a big cold spell coming I could remove the battery then and put it in my garage. I have a LiTime 100ah battery.

 

[reubenray]

I don't know how cold it normally gets where you live, but I'm in the Knoxville, TN area and we get into the single digits once in a while. Maybe not at all one winter, and then only a few days or so the next, but for the most part, not below zero.

So with my LiFePO battery, it stays in the camper. I have a 300A battery disconnect switch that totally takes the battery offline, except for the small milliamp draw from the BMS. When I winterize (usually in Nov.), I will get the battery SOC to between 50 to 55 percent SOC, turn that 300A disconnect off so there is no draw or any possibility of charging it. The battery is in the front compartment, next to the hydraulic stuff and the generator and temperatures in there are pretty much the same as outside air temperatures. So the battery just stays there all winter and slowly self discharges at a slow rate, plus the little bit of draw from the BMS. By the time that spring rolls around, I have gone from say 50% SOC (in Nov.) to mid to low 30% SOC in late March early April. I do check the SOC though throughout the winter, via the BMS app on my phone just to make sure that nothing unusual has happened. I built the battery in the spring of 2022, so it has been thru the winter of 2022, 2023, and is in storage now for 2024 winter storage.

If something way out of the ordinary for our area happened, like -15F was forecasted, I do have the battery inside a battery box that is insulated and heated that I could use to get through the crisis. I put it in for a "just in case" and have not had to use it yet <<<knock on wood>>>

Last year it got down to the single digits for a week here in NW Arkansas. If this is forecast I would definitely bring the battery to my garage.

 

[reubenray]

No it will not work properly on LFP.

You may know that you can purchase a quality LFP compatible charger that will slowly charge for about the same price, but I can see that you are trying to use what you have. NOCO

If you have not done so already, you may want to follow LiTime instructions (not a recommendation), here are only some of them: recharging to 100% (14.4-14.6V) every three months (possibly to balance cells for maximum life) and store at 50%. Many/most will tell you three months is not needed but I will follow the guidelines for my LiTime at least for now, while being skeptical at the same time. I wish I knew where some manufacturers came up with this and the results if I did not follow...

Also, not to keep battery on a charger in storage...

I already had that charge in my wish list on Amazon.

 

[triplethreat]

Last year it got down to the single digits for a week here in NW Arkansas. If this is forecast I would definitely bring the battery to my garage.

There really is no need to bring it in, as long as the battery has some charge still in it. As I stated above, I start out in Nov. with around 50 to 55 percent SOC and let the battery sit all winter long without recharging at all. In the springtime, say late March into mid April I'll dewinterize the camper and at that point, the battery is still showing SOC at approx. 35% state of charge. At that point, I will charge the battery back up to the 100% SOC before I start dewinterizing the camper......running the water pump, operating the hydraulic slides, etc.

The very first year that I built the battery and completed it...April 2022, that winter at Christmas time we had a stretch of cold weather here for almost a week. Several of the days was 1 or 2 degrees in the morning and warming up to maybe 10 degrees during the day, then right back down again that night. That went on for 5 or 6 days, with the overnight lows getting a bit warmer, but still in the single digits. My battery stayed put, in the front of the camper in the Hyd/Generator compartment....with the 300A switch turned OFF. There was zero damage to the battery and here I am almost two years later and the battery is fine.

The worst part about that time period was that TVA was ordering the local utilities to run "rolling blackouts" because of the lack of sufficient power for the grid in their network of power generation plants. That is of course totally off the topic for this discussion, but that situation has since been resolved too. They've got more power generation equipment available AND I bought a 15,000W emergency generator for the house that I can run if they take me off line...

If it makes you feel better to have it out of the trailer and gives you some peace of mind, then by all means, you can do that......but I'm just letting you know that it's not a necessity for the battery health as long as it is stored properly going into the winter with a SOC being enough to get through the winter...AND you've disconnected a lead from the battery terminal or installed a complete cutoff switch like I have. In the first picture I posted above, the large RED switch at the lower right of the pic is the 300A complete cutoff switch. The Pos. terminal of the battery has a high amp fuse attached to the battery terminal, and then the large cable goes from the fuse to the 300A switch. With that switch open, nothing can flow from the battery. The exception to that is the individual wires that are on the individual battery cells that go to my externally mounted BMS, and the BMS does use a small amount of current as it monitors the battery. We are talking something like 15 milliamps though which is expressed as 0.015 amps.