Multiplus forcing JK BMS into High voltage alarm while JK BMS in controll

Here they are. Both batteries are on the same settings. Hope this is what you mean

Cells are very well balanced. 0.008 defiacion max. But during changing it can get up to 0.281

A good starting point for the settings.

Disable DESS until battery fully charged and balanced.

Start Balance Voltage is set way too low. Change it to 3.42V at least - in the different sources you will find also 3.45V.

RCV Time is too long. Set there 1h.

That’s your issue. One or more cells are reaching OVP, others are way behind.

I have a few days ago checked all the connections in the battery to see if any were not tight. They are have the same torg. The cells are grade A automotive cells. So they should be ok right? Last night they were even balanced to 0.001 volt.
I have changed the bms’s to your adviced settings. It is discharging now, so cannot test. Hopefully tomorrow.
Thanks for all the advice and your time.
Will keep you informed

Ok, more info from today. I was watching it like a hawk.
The divergence of the cells starts at 97% charged. The cell difference is during charging 0.020 or less. Then it starts to clime fast, until it reaches 0.251 or so, when of course ovp happens. This happens within 10 minutes or so.
It is always a different cell.
Any hints?

Disable DESS. Enable Keep Batteries Charged for 2-3 days, until they will properly balance.

Ignore the errors, it only means that protection is working as expected.

After few days of top-balancing, bank should work as expected as the complete solution. Now for sure I’d try with above - settings are somehow good. Depends on who you ask, other parameters are commonly have lower or higher values - but marginal from your current setup.

EDIT: I’d even disconnect second bank, keep first connected until top-balanced, then switched and do the same with the second. Again, only one bank during top-balancing. After success on both, connect them together and start using + checking the situation.

These are the values after defiation start to rise.
Happens



realy quick

Change all your bms settings to Andy s settings (offgrid garage). Your RCV is too high and too close to OVP. For top balancing disable float mode and charge 24h. (RCV=3.450V (x16=55.2V))

Thanks, .
Am going to do that.
If that does not help, i will top balance every battery pack again just to make sure.
All this might take a lot of time, balancing might take a few days, maybe.
So i’ll be back, but it might take a while :wink:

I have just read that exactly the behavior i see in my batteries (getting high voltages difference at high charge % >97%) can be because of imbalance. I have balanced the cells of course when i installed them, but kept them at “keep batteries charged” for weeks because i did not have a dynamic contract yet. Now i have). As far as i can tell this might have led to an inballance that shows up at high % charged. I have been reading stuff all day, and this at least is my conclusion for now. But am open for input from those who know more then i do about this stuff.

So without any comments telling me the opposite i will set the bms to andy’s settings and then start a top balance. This might take while…

Zoek op youtube naar offgrid garage. Veel info over de jk bms en de settings. Mijn advies is om ook de nieuwste firmware erin te zetten.
Ik heb mijn accus samengebouwd en toen opgeladen met een lab voeding (wanptek 6020) en zo laten balanceren. Balanceren ging bij mij erg snel (paar uur). Nu is delta V tussen de cellen (4x 16xmb31) altijd ruim onder 10mV. (Nu 1 maand in gebruik).
Ik heb wel problemen met float mode icm DESS.

Succes

Limit the charging Amps to 50A and the Voltage to 56.8 Volts, the settings are in the DVCC.

If you won’t limit current and voltage you get these notices.

Here is an update.
Maybe it’s nice for all that tried to help.
I switch the mp off
Charged the batteries very slowly to 3.55 volt with the balancer on. Thought this would take a few days, but it was done in 16 hours. Cells were within 0.009 volt deviation.
Switcht mp on, set absorbtion to 56.8 volt and float to 53.4 volt. Absorbtion time on lowest possible (1 hour).
Activated dvcc again, switched ‘keep batteries charged’ in vrm to ‘wihout battery life’.
Connected the whole house to the mp again with the transfer switch.
Looks ok now, but I have to wait a few discharge/charge cycles to see if cell defiation stays within boundaries.
Thanks everybody for the input
In a week or so i will post the status for those who are still following this then.

this is on a quite high limit, isn’t it?

3,45/cell is MUCH more healthy…

See my message above.
I have ajusted it

Indeed, idiot me not digesting that.

I have set the values to this.
Also set almost all bms options conform those set by Andy’s offgrid garage
I have been running DESS for a week or two now and have seen no big battery differences and no overvoltage alarms.
But it must also be said that the batteries have not been higher charged then 96% by DESS. Every 4 weeks it should do a full battery charge (set in DESS settings) so i will wait for that.
But for the moment it looks like the batteries are stable after the top balance.
For now, thanks everyone.
Will report back in a few weeks.