two battery packs in paralell and SOC

[Alex1]

I have two DIY battery banks connected in paralell CALB 187Ah cells 2p8S, and EVE 280Ah 1P8S, each bank has JK bms, not same model.
Im not sure if CALB battery bank bms is showing correct SOC, and the EVE battery bank bms cant get to 100% SOC, when full charge.
I have calibrate current and voltage at 20A charge.

 

[sunshine_eggo]

What's your absorption voltage?

You likely need to hold the entire bank at > 3.50V/cell until current tapers to < 15A.

 

[Alex1]

What's your absorption voltage?

You likely need to hold the entire bank at > 3.50V/cell until current tapers to < 15A.

It is set to 3.45V, and i hold them like that, current drops below JK can measure. With that settings Calb get to 100%, but Eve never to 100%.
At summer I balance eve cells all to 3.65V, but soc still at 99%.
I was testing deep discharge once to 2.7v, maybe I can find pictures. Calb hit LVC and soc drops from 30%/40% to 0%, and Eve was on 5%, still discharging. But sill inaccurate Soc after that on calb
State at ~34A discharge per pack.

 

[sunshine_eggo]

99% vs. 100% is noise. I thought this was a significant discrepancy. Getting to 100% SoC @ 3.45V/cell isn't a sure thing.

The different models of BMS may use different criteria when computing SoC based on counting and then tweaking based on voltage.

If this was my battery bank, I wouldn't care.

 

[MisterSandals]

99% vs. 100% is noise.

Thats what i was thinking but I didn't comment because i thought i misread something, twice.

 

[Alarchist]

It is set to 3.45V, and i hold them like that, current drops below JK can measure..

Charging to 3.45V until 0 amps is overcharging! It should be terminated at absolute minimum 3.45v @ 0.014C = 3.92A for pack #2 and 5.236A for pack #1

Table for comparison here: https://diysolarforum.com/threads/charge-termination-current-at-desired-voltage.73424/

Check your BMS settings for why it's not resetting to 100%, or temporarily lower the trigger voltage on the string that doesn't go above 99% to make it hit 100% then reset.

 

[chrisski]

It is set to 3.45V, and i hold them like that, current drops below JK can measure. With that settings Calb get to 100%, but Eve never to 100%.

This sounds like the Eve BMS needs to be tweaked with tail current readings or synchronizing to 100%.

Unfortunately, not all BMSs are as adjustable as I’d like. My two have several % points off. I know each battery is at 100% when it does not take a charge.

I have a Victron shunt after where the batteries are combined providing accurate data.

 

[Alex1]

Problem is with calb bms and 48% soc at average 3.187V cell, think this is not even close to real state.
I use SOC for Red Node to trigger at 30% inverter from SBU to Utility.

99-100% Soc is not a problem.