SOK BMS wildly inaccurate

[chateau_nomad]

For clarity, here's the text from an email I just sent to sales@sokbattery.com...

I purchased two SOK 12V 100Ah LiFePO4 Batteries with Bluetooth & Built-in
heater in March of 2023, and recently another one - for a total of three
100Ah batteries.

Upon receipt of each battery I completely discharged to "cutoff" (the
battery appeared dead). I then used the "wakeup" procedure (momentary
connection with a 12 volt lead-acid battery). Then I used a Sungoldpower
inverter/charger @ 20 amps to fully charge each battery to cutoff.

In the SOK app, two of the batteries are showing 100% charge. The other is
only showing 72%, and will not accept more charging. Please note the wildly
inaccurate CALC Capacity reading.

I have been using the two older batteries in parallel - equal length cables
- since installed in my motorhome for about a year now. The readings from
the two older batteries haven't changed significantly. However - I seem to
be getting the full rated capacity of 200Ah according to my QWORK shunt.

The newest battery display seems correct. However I haven't connected it in
parallel with the other two batteries yet. My intent is to have a total of
300Ah capacity.

Is there a possibility that the BMS boards in the older batteries are
malfunctioning?

Please refer to the attached screenshots.

 

[Arion]

I've run three SOK 200AH batteries in parallel for a couple of years now and the BMS has never been accurate. Really don't need to bother with it as with a decent battery monitor it tells you most of what you need to know anyway. I will say these are definitely good batteries though all three of mine have capacities of over 210AH so no complaints.

 

[ScrotusGobbleBottom]

I would read this as you have 1 battery behaving and 2 that are have a bad cell/unbalanced or cells hitting high voltage cuttoff and defaulting the BMS to 100%.

 

[ScrotusGobbleBottom]

This is a MAJOR problem. I guessed right. Battery 2 is having a balance problem
Cell 3 looks the best. Cell 1 is starting to struggle.