question

alex-frood avatar image

BMV-712 Relay to switch off DC to DC Charger and MPPT remote ON/OFF Pins

Hello, could anyone give me some information regarding the best way to set up Relay on the BMV-712 for use in my Campervan


I would like to use the BMV-712 relay to switch off my Victron DC to DC charger & my Victron 150 | 60 MPPT via there Remote ON/Off ( L & H ) pins in case of Low battery temperature ( or another trigger I wish to use ) . I have temperature sensor for the BMV and want to use the low temperature trigger to trigger the Relay.


Wiring wise what would you recommend? What output on the BMW and which pins in the Dc to DC & MPPT should I use?


Just so I'm getting this Correct the "L" pin Supplies a 3.3v Live, When the "H" pin Receives a voltage of 3v or higher it turns the device on, and less the 3V it turns the device off? If this is the case could I Ignore the "L" pin on the devices and Wire a 12V live from the Battery into the COM port of the Relay and then just Parallel the "H" pins from the NC relay port. when the Relay in the BMW is normally closed the charger & MPPT would be ON, when the low temperature triggers ( or any other trigger ) , it will open the relay which would turn off the Charger and MPPT ( and prevent my lithium battery is charging when cold and my Batteries internal BMS doesn't have low temperature charge cut off ) 

OR would I use DC/DC Charger & MPPT L pins in Parallel wired to the COM relay port on BMV, then NC relay port wire in Parallel to the H pins on the charger & MPPT.

Since I want to control both the DC/DC charger and the MPPT remote On/OFF at the same time from the BMV relay. Running the output ( NC ) In parallel to multiple things shouldn't be an issue should it?


Cheers
-Alex
BMV Battery MonitorchargerRelayswitch
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4 Answers
wkirby avatar image
wkirby answered ·

Your first explanation is correct.
Wire the H pin of both MPPT and DC-DC to the NC contact of the relay. The COM of the relay to battery +.

Alternatively, you can wire the L pin of both to the NC of the relay and then the COM of the relay to battery -. When L is connected via NC relay to battery - then the devices will be on.

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james241990 avatar image
james241990 answered ·

Hi, we can say that I have a similar problem. I have an Orion-Tr Smart DC-DC charger 30A and a SmartSolar MPPT 100/50 solar charge controller that recharge a 310Ah LiFePO4 battery.

I want to set the BMV-712 Relay to turn off the Orion and MPPT when the battery reaches 90% SOC and turn them back on when it drops below 80% SOC.

Can you tell me how to make the connections and which cable to use to connect to the Ve.Direct of the MPPT? Thanks so much.

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kevgermany avatar image
kevgermany answered ·

As far as I know your MPPT does not have this possibility, there isn't an external switch connection. The Orion should be connected as @WKirby said above.

It might be possible to switch a relay installed between the panels and MPPT.

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james241990 avatar image
james241990 answered ·

Yes, it is also possible to switch on and off the MPPT 100/50 remotely, using the VE.Direct non inverting remote on/off cable which, as explained by @WKirby, must be put in parallel with the H pin of the DC-DC and both to the NC of the relay.

In this way, when the SOC of the BMV falls below a set %, the relay closes and turns on the two, the DC-DC and also the MPPT.

However, from what I have read in the manual, it is not possible to give more than one setting to the relay. For example if I want to check both SOC % and low temperature (through the BMV sensor) it is not possible. This is right ?


What I can do is create a VE.Smart network with the MPPT and the BMV-712 so from the MPPT settings deactivate it when the temperature drops below a certain set value, for example 5 ° C. But I cannot also turn off the DC-DC which does not have the VE.Smart network.


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