question

cheng74 avatar image
cheng74 asked

Connecting multiplus and managing it with REC BMS - solenoid disconnect or not ?

Im planning a new installation onboard; 12v system 4x400Ah Winston cells and REC BMS 4 with a Multiplus 12/1600/70 inverter charger, monitored with a Cerbo GX. The invcharger is to be connected to batteries unswitched - Here is the the problem; REC BMS wants a protection/isolation switch between the battery and Invcharger. See attached picture from REC BMS4 manual.

screenshot-20220206-124849-drive.jpg

My question; Can we skip the encircled breakersolenoid, getting a straight unswitched connection and instead just shutdown the inverter appropriately on a REC BMS signal when cellprotection/isolation is needed? Either over the VECAN / Cerbo GX or physical relay on the REC BMS ?

Best regards, Fredrik

BMS
screenshot-20220206-124849-drive.jpg (95.9 KiB)
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2 Answers
wkirby avatar image
wkirby answered ·

Indeed, a far more elegant way would be to use a signal or a relay contact connected to the Remote On/Off connector of the MultiPlus.
An open relay contact would disable the MultiPlus in this case and the battery connection could remain interrupted.

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carl-dewever avatar image
carl-dewever answered ·

So we connect the on/off switch of the multiplus to the rec bms.
That makes that when the batteries are at a dangerously low SOC the charger/inverter will shut down.
However, is it possible to start the charger in that situation to recharge the batteries? In other words, is only the "inverter side" of the multiplus shut down? Or are both inverter and charger disabled?


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