Yesterday I observed a deadlock with my BMS-NG 500. If the BMS runs into low battery it switches off. That’s ok. But at the same time the BMS-ATC signal is off. So my B2B charger Orion XS12/12-50A controlled by this ATC signal goes off too. I removed the load an tried to enable the BMS switch via VictronConnect. No effect. By shorting the ATC signal the Orion starts again delivering 12V to the BMS on the load side and I could enable the BMS switch. Without the power from the B2B charger the BMS never switches on. Silly isn’t it?
That’s normal and described in the manual:
I cannot see any sense in this behavior. If the battery is going low why is it forbidden (ATC) to charge it again?
If it has got so low that the contactor has opened then it is completely disconnected so charging is not possible.
That’s ok. But why couldn’t the BMS switch be controlled by the Victron app and why is the ATC signal off? You have to do several things to manoeuvre out of this situation. This is not very user friendly in my opinion.
Have you read the paragraph that Matthias linked? Did you follow the described prodecure, switching it off for 5s then switching it on again? If yes, then that would be an issue with the BMS/its frimware since it should have woken up from standby again.
Thats also mentioned in the linked paragraph, to conserve as much energy as possible the BMS powers almost completely down. It doesnt know if this situation will be there for only a few minutes until someone reacts to it, or several days or even weeks.
Yes, and that is indeed unfortunate. I was in a similar situation once, but to be honest it was my fault to even get there, since several things were necessary to go wrong/be setup incorrectly in order to even get into a low voltage disconnect
There is a simple solution preventing this deadlock: A programmable ATD level - e.g. stop ATD at 50% SOC.