chayr said:
switch is connected on relay (2x24= 48) and it cut the B+ before BMS.
Both voltmeters was connected after bms P- & B+ P+.
hmm, how exactly does the relay(s) cut and why!?
If you have cut bms P+ off from Battery+ while you have the balancer plug (B0..B13+) connected or any other power, this is the mentioned condition known from several cases to damage/kill smartBMS - e.g. in some threads of this forum. Did you do this practice from beginning? Or what was your setup BMS connection order? and BMS disconnection order?
(Being aware of, I didn't dare to make this "20$-test" intentionally ever, to fully confirm those damage stories.)
I mentioned this condition extra in an earlier post here to warn avoiding this under any circumstances.
From datasheet:
(VCC --> P+ pad; Ground --> B- pad)
chayr said:
Now the BMS where I make the reset always cut after a few second (see on video).
On the second BMS I didn't do any reset.
So you say, the one reset'ed BMS permanently irreversibly changed/worsened its behavior - sort of more defect than the other? No discharge possible? Reset was done while P+ was cut off?
This sadly would make more likely that you have/had balancer plug on, while P+ disconnected ... you mention such important things very late ...
I'd recommend to become very aware of right connection/disconnection order before possible risking on the 2nd BMS - which with some probability may be already half defect.
Question is now, if you want live with that half-functioning BMS#2 as it is now? (>1A charge problem only; check of correct critical functions OV/UV recommended; avoid P+ cutting)
Or (b) if you are interested to analyze the condition of at least the better bms more exactly without I2C first? (Rather precise answers about the questions left regarding LEDx , R17/sleepmode and exact voltages "+V3.3", "+V12"; is there 2s charge restart by
dis-/reconnecting just the charger? ...)
Or if you want try to deal with bmsbattery - though you perhaps damaged things yourself ...
Or ...
I2C check/programming (after (b) perhaps) with standard interface is possible but complicated byte peeking&poking. More or less HW damage of both BMS'es yet may already be the situation; prospects of cure by I2C are not 100%.
A $100 I2C interface with OZ/SmartBMS PC software exist from bmsbattery.
I use since long time a own Bluetooth I2C hardware with own Android & PC software for OZ890/SmartBMS for advanced logging, programming etc - example log curve
here.