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Missing Instruction set


Maybe I'm just missing something, but going through the values in my Active BMS, I don't see a complete instruction set in the REC documentation.

I'm missing the commands to query or set Opto Coupler 1, Relay 2 and their respective Hysteresis as well as the Hysteresis for CLOW (Under-voltage discharge protection)

I also presume that CLOW is actually the Discharge switch-off before CMIN (Cell Under-voltage Protection Switch off) is reached. Is this correct?

Is there a full set of commands available?

David Marks and Rich Marshall have reacted to this post.
David MarksRich Marshall

not sure what manual you have but here is the link to the current ABMS manual for use with Victron.


It looks like what you need is on page 13

And yes, CLOW is the value that the BMS will use for disabling your system loads via CANBus.

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  • ABMS-commands.PNG

Thanks Rick

Maybe I just dont understand how this works - are there not two Relays and two Optocouplers?

RE1L and OP2L being Relay-1 (pin 1,2&13) and OptoCoupler-2 (pin 16&17) respectively - What are the same commands for the Main Relay (pin 3,4 & 5) and Charge OptoCoupler  (pin 14&15)?

Pete, the way the "Victron" version of the ABMS works is like this.

Relay DCH is meant to be connected to all Victron loads and charge devices. (Non Victron loads can be added here in a single contactor configuration) The BMS will first issue pullback commands to the Victron inverters, MPPTs and chargers on the VE.CAN network.  If the system continues to over or under charge, it will open the DCH relay based on the BMS cell high and low settings.

The second relay (CH)is meant to be used with old style devices that can not be shut down via CANBus or an opto coupler interlock circuit and the REL1 and REH1 settings are used for that.  See attached sketch.

This configuration allows for a 3 stage shutdown process and an example might be something like this:

  • BMS detects an approaching UV cell condition
  • First it issues a CANBus command to shut down the Victron inverter to reduce the system load
  • cell voltage continues to drop.....
  • Second, it issues a CH Relay1 open command based on the voltage levels set using REL1 and REH1, which will shut down all manually connected loads
  • cell voltage continues to drop .....
  • Third, as a final safety it issues a DCH relay open command and all Victron devices are disconnected


If you set RE1H to a positive value it is used for UV (under voltage) applications where you want to shut down a manual load

If you set RE1H to a negative value it is used for OV (over voltage) where you want to manually disconnect charging devices.

If you set both to 0V it is disabled


Clarification from Tine at REC.

ABMS for Victron already has the Discharge/MAIN relay programmed for UV and OV protection and wiring the CHARGE relay is not required. CHARGE relay may be used for OV and UV for other purposes and is configurable with instructions RE1L and RE1H. If the RE1H is positive it is for UV protection, negative for OV protection, if set to 0 V it is disabled. The customer may connect any signal to the CHARGE F input. Some of the devices are controlled by applying ground so ground is connected to fused input and NO then connected to a controlling device.

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