"Smart Balancing" - A better way to maintain cell balance.


Solar Addict
Dec 6, 2020
thank you for your feedback, so you can confirm the main contactor never open on canbus loss?
I will install a recbms16s next week and your information is really appreciated, i will just add WS500 alternator controller on your setup!
Because i have seen 20000$ damage (autopilot and every 24v smart devices fryed) on sailing boat just because a not smart enough alternator controller, not properly configured for a good talk with bms. it's was mastervolt but same topology, software incompatibility lol.
Damage is from very inductive charger, typically alternator winding, not from high frequency switching charger.

The REC will only open the main contactor if one of it's safety parameters is violated. Those all come from the BMS itself (battery cell voltages, temp sensors and shunt).

It does send out over CANBUS in the CVL, CCL, and DCL targets - for example if the BMS senses the battery is too cold to charge it will set the CCL to 0 so any CANBUS equipment is aware to not try to charge.

You could have a situation where the main contactor gets opened by the REC and it is also telling the equipment via CANBUS to "set charge to 0 amps" which is not a bad thing to happen, if the equipment is still powered with the battery disconnected.
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"Move over... let me fix it" Installer/Engineer
May 1, 2020
USA - Working in Central America
My biggest question is what if there are multiple batteries with separate BMS?
The logic here would use a Master+Slave configuration on the BMS side, with only the Master BMS communicating with the inverter. The Master BMS would review the requests from the slaves and send appropriate commands to the inverter based on the total requests including its own.

I don't recommend Heltec for this. If you want a good Chinese BMS with this functionality baked in, Seplos is the best we have found. I sell them if you are interested. Up to 200A per BMS. Outside of that, I would only use Orion BMS units with Deye/SOL-ARK. Orion is our defacto BMS unless it's a budget install.