question

Lionel SEYDOUX avatar image
Lionel SEYDOUX asked

How can I set a relay to activate on high SOC?

Hi everybody,

Up in the southern french Alps, My offgrid house is powered by 2kW panels, managed by MPPT 150/65, feeding 30kWh lead batteries. The load is fed by Multiplus 24/5000/230. Monitoring by BMV712, CCGX and VRM. Soon some irradiation device.

That is just enough for Winter solstice days when occupied, but otherwise some 1 to 6kWh are lost. The idea is to use it to warm the technical room to prevent any risk of freezing batteries and/or help heat the water tank.

Could not find any relay that would close when SOC is above say 95%. and stay otherwise open. I understand an inverted low SOC alarm could do, but not sure.

Thanks for any tip!

Lionel

SOCRelay
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5 Answers
Matt drummond bell avatar image
Matt drummond bell answered ·

I too have asked this question, and nobody got back!I believe you can use the multi relay,on soc but I never worked out the programming!

I did read some where that somebody had written or nearly written the programming for either the solar charge controller, or the color control to switch dump load based on solar voltage but I can’t find where that was, which would be great for me to run immersion when batteries fully charged etc! Good luck!

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Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Just checking the logics in the doc (I am away from my system): What we need is a relay that closes above say SOC=95% and opens under that value.

On CCGX: tank pump or Gen relays : normally closed when SOC (? not documented) low . Polariy inversion possible.

On BMV: Buzzer on if SOC low: no do to use it outside. Polarity inversion not documented, Could be done via outside relay

On Multiplus: apparently nothing working with SOC, only AC or DC Voltages..

Anyway, after one of these, we must have a bigger separate power relay to switch the power toward the heating device

We shall have to ask someone @mvader (Victron Energy Staff)? who seems to know everything :=)

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Lionel SEYDOUX

Use the Multiplus:

You can use SOC as a trigger with the 'programmable relay' assistants, and use AC-out2 to directly power a load.

You can also use the 'generator start-stop' assistant for even easier programming.

https://www.victronenergy.com/live/assistants:start

https://www.victronenergy.com/live/assistants:overview_of_available_assistants

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Rob Fijn avatar image
Rob Fijn answered ·

Hello Matt and Lionel,

You can use the relay on the BVM for this.
Option 12 of the menu will allow you to Invert the relay.
So when doing this the menu 16 (SOC Relay) is then your signal that change when the SOC is 95%.

The older MPPTs with CAN interface have a relay. Also the Quattro's, this can be programmed with the VEconfig to what every you need the relay to do for you.

Hope this helps.

Rob


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Lionel SEYDOUX avatar image
Lionel SEYDOUX answered ·

Thanks @Daniël Boekel (Victron Energy Staff) and @Rob

Clear now, as you sent me the right references.

Cant Victron gather all indexes, including theses discussions, into a big one, with the reference of the original doc. That would help finding the right answers!

Thanks again

Lionel

1 comment
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Hi @Lionel SEYDOUX

Yes there is room for improvement there.

For now the search function is your friend:

https://www.victronenergy.com/live/start?do=search&id=dc_distribution&q=assistants

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