LIFEPO4 Battery discussion thread

cavedog

cavedog

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I thought I would create a thread for this to chat about all things LIFEPO4.

Instead of cluttering the other thread with my questions and posts I decided let's create a thread here. @wingnut771 @Lupus @denmendez65

So Ecco recommends charging voltage of 58v for their packs. The Pacebms doesn't like that as the default ovp warnings are at per cell is 3.5v and the cutoff is 3.65v. This means charging at 58v will fill the log with a bunch of OVP warnings over time. Now that I added my second battery I saw the bms actually hitting a cutoff when it was charging at 99% and reached 100%. I want to top balance the cells as I never really did that since getting them especially now that I have 2 in parallel.


There is so much information out there. People say 58v for 16s is fine for charging and top balancing but then @wingnut771 suggested 56.4v as bulk for daily charging.

Chatgpt says hitting bms cutoff all the time is not safe because that is the last form of protection if it fails cells get over charged or discharged which causes damage so rather control it before cutoff but how do you balance then not knowing what these BMS's will need to start balancing. The manuals also don't say anything about balancing and how you should handle these packs.

Looking at battery 2 which is the new pack. It hit a hard cutoff from the BMS and from what I can see doesn't look like its balancing. Battery 1 is my original battery and seems pretty well balanced and happy with that but the Pacebms obviously did log the overvoltage warning.

There are so many different opinions on what to do and what not to do it makes things so confusing.

Screenshot 2026-05-12 152321.png


Screenshot 2026-05-12 152537.png

Battery2 (new battery) seems fine. It shows 99C soc in the detailed screen but on the home screen 100% and it looks like its slowly balancing now after it hit the cutoff so maybe the voltage was bit too much or my inverter didn't slow down enough when it was almost full.

20260512_153651.jpg
 
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That's @wingnut771 and others' department. I know little of Lifepo4. I am still on LA batteries, which I researched fairly well and just got lithium on the second inverter, which is still running on default charging voltages as it seemed to be ballpark in the range of what I saw elsewhere.

Looking forward to learning from the experts here on Lithium.
 
These pics are confusing all with different voltages.

You want to have at least 3.45V per cell (55.2V pack voltage) to be 99.9% SOC and not going into the steep part of the voltage curve where it just ages the chemistry faster without anymore capacity.

I see battery 1 looks pretty balanced now (I remember this being a problem in the beginning and why you dropped charge voltage to stop the errors).
1778595490710.png

Battery 2 has some way to go to balance:
1778595669163.png

So not sure why we see 54V (maybe its floating?), but can only really check cell balance at 55.2+V.

Anyway, I would use:
BULK 55.2V
FLOAT 53.6V
LOW 44V

Above values are on battery side so factor in voltage drop on inverter side.
 
Might be a good time to drop this from https://www.youtube.com/@OffGridGarageAustralia/featured

He has a few stacks of batteries.
1778610865615.png
He charges to V55.20 just like wingnut said

Just make sure your pacebms is set to reset 100% SOC at that voltage.

Main problem is lets say you call for 55.20 charge voltage and the 100%SOC reset is at the same voltage. The voltage drop from inverter to battery might be to high for a reset and you might need to bump the charge voltage to 55.6-55.8
 
wingnut771 said:
These pics are confusing all with different voltages.

You want to have at least 3.45V per cell (55.2V pack voltage) to be 99.9% SOC and not going into the steep part of the voltage curve where it just ages the chemistry faster without anymore capacity.

I see battery 1 looks pretty balanced now (I remember this being a problem in the beginning and why you dropped charge voltage to stop the errors).
View attachment 1907597

Battery 2 has some way to go to balance:
View attachment 1907598

So not sure why we see 54V (maybe its floating?), but can only really check cell balance at 55.2+V.

Anyway, I would use:
BULK 55.2V
FLOAT 53.6V
LOW 44V

Above values are on battery side so factor in voltage drop on inverter side.
Click to expand...
Something interesting my new set of photon batteries with newer pacebms wont float voltage if they hit 100%SOC.

As soon as the 100%soc is hit they turn the charge mosfets off and will only turn themself on if the SOC drops a few %

I watch them on Pbms the other day, One of the batteries will hit 100% just tad before the other one and you can see the voltage drop as soon as the charge mosfets turn off. So even you are running open loop with a set voltage it wont let you float the battery itself
 
DTBA said:
Might be a good time to drop this from https://www.youtube.com/@OffGridGarageAustralia/featured

He has a few stacks of batteries.
View attachment 1907649
He charges to V55.20 just like wingnut said

Just make sure your pacebms is set to reset 100% SOC at that voltage.

Main problem is lets say you call for 55.20 charge voltage and the 100%SOC reset is at the same voltage. The voltage drop from inverter to battery might be to high for a reset and you might need to bump the charge voltage to 55.6-55.8
Click to expand...
I dont think he can change any settings on bms. Also, that 52.50V in the pic is wrong and a typo.
 
DTBA said:
Something interesting my new set of photon batteries with newer pacebms wont float voltage if they hit 100%SOC.

As soon as the 100%soc is hit they turn the charge mosfets off and will only turn themself on if the SOC drops a few %

I watch them on Pbms the other day, One of the batteries will hit 100% just tad before the other one and you can see the voltage drop as soon as the charge mosfets turn off. So even you are running open loop with a set voltage it wont let you float the battery itself
Click to expand...
LFP's dont float anyway so I'm okay with that. This is why you set a resting voltage for float.

What is 100% soc for the newer pacebms?
 
wingnut771 said:
I dont think he can change any settings on bms. Also, that 52.50V in the pic is wrong and a typo.
Click to expand...
52.50 in the picture is to calibrate the jk bms with a multimeter ? if we talking about this:
1778612305644.png


I was talking about this voltage:
1778612350851.png
3.450*16=55.20
 
Main reason I am asking is I see some random battery makers like to set 100%soc only when the battery is at 56v ><
 
DTBA said:
Main reason I am asking is I see some random battery makers like to set 100%soc only when the battery is at 56v ><
Click to expand...
Well these counters aren't very accurate anyway so I wont lose any sleep if its a few percent out.

At the same time other manufactures make 3.65V cell OVP reset 100% counter which is just wrong.

Anyway, 56V is pretty close to 55.2V and much better than 58V.
 
wingnut771 said:
Well these counters aren't very accurate anyway so I wont lose any sleep if its a few percent out.

At the same time other manufactures make 3.65V cell OVP reset 100% counter which is just wrong.

Anyway, 56V is pretty close to 55.2V and much better than 58V.
Click to expand...
I have seen a few that will only reset at 58V. 100% agree 56v should be fine and give enough time for slow charging at the top for balancing


1778612847324.png
 
DTBA said:
Something interesting my new set of photon batteries with newer pacebms wont float voltage if they hit 100%SOC.

As soon as the 100%soc is hit they turn the charge mosfets off and will only turn themself on if the SOC drops a few %

I watch them on Pbms the other day, One of the batteries will hit 100% just tad before the other one and you can see the voltage drop as soon as the charge mosfets turn off. So even you are running open loop with a set voltage it wont let you float the battery itself
Click to expand...
My Omnivolt exhibits this behavior. Hits 100% and it kills the charge completely.

After a few hours can see battery SOC dropping to 98% even when running in pass through with the 3.6 supplying the load.
 
denmendez65 said:
My Omnivolt exhibits this behavior. Hits 100% and it kills the charge completely.

After a few hours can see battery SOC dropping to 98% even when running in pass through with the 3.6 supplying the load.
Click to expand...
A lot of bmses do this it seems, micro cycles. I noticed the sunsynk battery too, would only start charging again at 95%.
 
wingnut771 said:
These pics are confusing all with different voltages.

You want to have at least 3.45V per cell (55.2V pack voltage) to be 99.9% SOC and not going into the steep part of the voltage curve where it just ages the chemistry faster without anymore capacity.

I see battery 1 looks pretty balanced now (I remember this being a problem in the beginning and why you dropped charge voltage to stop the errors).
View attachment 1907597

Battery 2 has some way to go to balance:
View attachment 1907598

So not sure why we see 54V (maybe its floating?), but can only really check cell balance at 55.2+V.

Anyway, I would use:
BULK 55.2V
FLOAT 53.6V
LOW 44V

Above values are on battery side so factor in voltage drop on inverter side.
Click to expand...

So, cell damage only happens at less than 2.5V right. The BMS cuts off before that anyways like the master pack cuts off at 44V and the secondary one cuts off at 44.80V overall.

I think low V cutoff on my inverter should probably be like 45V or so. What do you think?

The guy in the diy solar youtube videos actually did videos showing that time ages batteries faster than a 100 - 0% soc cycle daily.
 
cavedog said:
So, cell damage only happens at less than 2.5V right. The BMS cuts off before that anyways like the master pack cuts off at 44V and the secondary one cuts off at 44.80V overall.

I think low V cutoff on my inverter should probably be like 45V or so. What do you think?

The guy in the diy solar youtube videos actually did videos showing that time ages batteries faster than a 100 - 0% soc cycle daily.
Click to expand...
Yes indeed, batteries can be set to 40V but not sure if they will need a jump start after that so better to leave a few volts on the table. Not much capacity wasted between 45 and 40V.

I’ve always said calendar aging is a thing, but charging to 3.65V and high temps would accelerate this, 3.45V is better as that is also 100% soc.
 
Charge to 100% and discharge to 0%. @wingnut771 What do you think about this?

 
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