I have an installation consisting of a MultiPlus 48/5000, four 12.8 V/90 Ah batteries connected in series, a CCGX and a SmartSolar MPPT 150/85 VE.Can.
For the past few days, the system has been switching back and forth between Sustain mode and Self-consumption mode at very short intervals (i.e. every minute or two). The consumption (AC-out 1) at that point is around 2,500 W and solar production is low (at the end of the day, 100 to 200 W). Sometimes the CCGX even shuts down and restarts (the BMS cuts out).
I suspect that one or more of the batteries may have unbalanced cells. I have read the procedure for rebalancing them individually using a Blue Smart charger, but I don’t have one.
Is it possible to perform this rebalancing using the MultiPlus? (I can disconnect the Victron system from my electrical installation to do so.)
In my opinion, connecting them in series is always problematic.
(Although it usually works reasonably well with Victron batteries, since you have a higher-level BMS.)
You should disconnect the system and then measure the voltage of each battery first.
After that, charging them individually (or in parallel) would be best; that’s the only way to bring them all to the same voltage.
You won’t be able to balance them properly when they’re connected in series.
It’s important to charge them at a low current, and the BMS must be able to disconnect the charger or charging current.
So it needs to be done with a Blue Smart charger. If I understand correctly, the BMS also needs to remain active during balancing. How can the BMS control this charger? I’m using a VE.Bus BMS in my system.
Since the VE.Bus BMS load-disconnect signal is high (12 V?) during normal operation, can I use a 12 V DC/230 V AC normally open relay to power the Blue Smart charger? If it goes low, the charger will switch off. Is the BMS load-disconnect high state indeed 12 V?