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Dosheimer avatar image
Dosheimer asked

Multiplus: Relay usage for hot water boiler when plenty of sustainable energy available

Hi to all!

I have a multiplus 12/3000/120-50 on my sailing yacht and what I would like to do is that the hot water boiler (800W / 230V) shall be powered in case I have plenty of sustainable energy available.

In detail the hot water boiler shall be powered on in case all of the following conditions are true at the same time:

- no power from shore power connection (to avoid unnecessary energy costs)
- battery capacity is >99% (BMV 712)
- voltage is >13,3V (indication that should be energy available from solar or wind generator / to be discussed)

Is there a change to program one of multiplus relais accordingly?
Best would be that the hot water boiler would be powered for 15 minutes and then the above mentioned conditions should be checked again (in a permanent loop).

My today´s setting:
- Multiplus 12/3000/120-50
- Bluetooth Smart dongle (at multiplus RJ45 VE.Bus Port)
- 4x100Ah AGM parallel at 12V with Victron battery sense (to be replaced by LifePO4 in future)
- 900W of solar energy (at Victron MPPT 50/100 12V)
- wind generator (Silentwind Pro 12V) with 12V MPPT hyrid battery charger
- 500A Victron shunt connected to BMV 712
- MK3 USB and Victron Ve.Direct USB connected to my notebook running Victron Connect
- hot water boiler 800W/230V Sigmar Marine „Compact“ SM20 with thermostat

I do not find a good documentation of the relay´s of the multiplus and possible individual programming and therefore your assistance would be highly appreciated!

Many thanks in advance!
Dos

MultiPlus Quattro Inverter Charger
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2 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @Dosheimer,

I don't think this can be achieved with "conventional" assistants in VE.Configure, at least not in the manner you described.

But the good news is that there is another solution to accomplish your goal, which is to use the Venus OS large image either on a GX device (Cerbo GX or Venus GX) or Raspberry Pi and then using the embedded Node-RED.
With that you can exactly do what you want and plenty of other things.

Read more about it here: Venus OS Large: Node-RED and Signal K

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Dosheimer avatar image
Dosheimer answered ·

hm, it would be a pitty if it´s getting that complicated as this might be a "standard" requirement for a lot of installations in the area of sustainable energy usage.

Maybe instead I simply use a Shelly1 PM IoT relay at the hot water Boiler. This I could power on via simple http even in saying ON for 15 minutes just by using a parameter shown in their Shelly public API documentation.

Still the state of charge I will need from the BMV 712 to write my own program when to do the http to the Shelly relay. I will have a look at the USB port at my notebook after connecting the BMV 712 via VE.direct to USB interface. This interface cable hopefully uses some kind of virtual COM port at my notebook and using i.e. Putty I will have a look at the data running in. Someone posted some information about reading out the VE.direct Bus at the BMV a few years ago:
http://www.deszynski.com/victron-bmv-700-lan-port/

In case having SOC read out then I could do my own program using the Shelly 1 PM instead of Victron.

As said, it would be a pitty in case this cannot be solved via my Victron relay settings after having invested so much in all my Victron components.

But thank you Stefanie, in case I will not get it running the Raspi Venus OS could be an alternative solution...

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Stefanie (Victron Energy Staff) avatar image Stefanie (Victron Energy Staff) ♦♦ commented ·

I did never say it's not working. All I'm saying is that it doesn't work just out of the box, at least not when it gets a bit more complex.


There are plenty of other ways to achieve this. There are plenty of solutions on Github to read from the BMV via the VE.Direct.

A good starting point if you wanna write your own code here: VE.Direct Protocol FAQ

and here: Data communication with Victron Energy products

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Dosheimer avatar image Dosheimer Stefanie (Victron Energy Staff) ♦♦ commented ·

Hi Stefanie,
Thanks for your response (my 2nd post sounded maybe more negative than meant :-)
The more I am checking youtube videos concerning Raspi and Venus the more I think I will go for that and the Node-Red solution which you have proposed.

Thank you very much for your help!


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