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Hi, I am building a setup in my van and wanting to know if I can use power from my mppt when my battery is fully charged without using my battery.

For example, my idea is to have 12v electric underfloor heating in my van. If my battery is fully charged I want to power the heating but don't want it to deplete my battery.

Same theory to heat my water tank.

So when I come back to the van, I have a full battery and possibly hot water and a warm van. I have a diesel heater if it gets cold.

If possible, how do I wiring this?


Dom

MPPT Controllers
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4 Answers
Paul B avatar image
Paul B answered ·

put a control relay in the turns on using a timer after say 1 or 2 hours of battery voltage at over 14 volts then also turn off if the voltage falls below 13 volts

this way the battery will be close to 90 to 100% and as long as you dont draw more amps than the solar can provide then you are fine.

as long as you stay above 13 volts you wont be drawing from your battery.


this is a very ruff way of doing it and the idea would need to be tested due to current draws as I have no other information about your setup

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dominicrose avatar image
dominicrose answered ·

Thanks for the reply, I currently have two LG 250watt panels

The victron blue smart 150-35 charger coming tomorrow. I'm pretty sure that's the one.

I only have a victron smart 12v 90amp hour lithium battery.

Besides that I have a victron cyrix-lt-ct to go to the 2005 iveco daily alternator.

That's all I have so far, not sure what I'll need.

Oh and the underfloor heating is 12v 150w 2m2 from prowarm.

Any advice would be greatly appreciated!


Kind regards

Dom

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Wayne avatar image
Wayne answered ·

If you have or install a BMV shunt it has a built in relay that is programmable, I have done that with mine and use it to heat hot water, programed to start when SoC hits 99% and off @ 95%. My vav set up is 2000W PV 600Ah LiFeP04 3000VA Multi the hot water is 1000W and runs via the inverter,

I have a mate with a very similar set up and he uses a 12V 300W element in his hot water..

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briona112 avatar image
briona112 answered ·
You don't need to do this. The inverter is fully programmable. You can just setup a rules to make this happen. At the very least you can just use an AUX input on the inverter to trigger grid disconnect and the best you would just disable feed-in via Modbus/MQTT or NodeRed
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