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Fredu12345 avatar image

BMV712 with AGM+MPPT+Multiplus gives 0% after a while

Hi, my BMV712 starts off from 100% when I start up the inverter (Multiplus Compact 1600VA) but then slowly drains to 0% and never rises above it again. The MPPT however gets to float nicely every day and stays there. I have a refridegarator connected to the inverter so it does go on every now and then but still the MPPT stays on float.

Dunno what’s wrong. My BMV settings are as follows.

MPPT - Solar Charge ControllerMultiPlus Quattro Inverter ChargerBMV Battery Monitor
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6 Answers
JohnC avatar image
JohnC answered ·

@Fredu12345

The negative cable from your mppt must go to the other side of the shunt. Like the same point the neg from the Multi goes to.

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Fredu12345 avatar image
Fredu12345 answered ·

Hmm. Still the same issue. There’s probably some setting that is incorrect. No matter if the batteries are fully charged the percentage on the BMV only drops.

Screenshots below. I have no idea what to do...



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Fredu12345 avatar image
Fredu12345 answered ·

Awesome! Thank you!!!

One more question: what should I select for the input: starter battery, temperature or mid point. And what does that even do?

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@Fredu12345, please familiarize yourself with the user manual, as all of these questions, as indeed the proper connection of the BMV, are fully answered in it.

@Fredu12345

The 'mid point' is normally used for higher V batt strings, or batts of smaller cell components to warn of a failed batt/cell. Probably not applicable to you. Forget it if you have no mid-point terminal to connect to anyway.

The other two are for you to choose between. Temp is a bit dull, unless you need it to interface, and Starter Batt V depends on how much you value it. You can change at will if you're set up for both.

Fredu12345 avatar image
Fredu12345 answered ·

hi,

And thank you kindly for your help here is a schematic diagram I have the shunt between the inverter and the minus cables between the two batteries. Then I also have a red cable going to the shunt from the plus pole of one of the batteries. Can’t remember exactly but I think this was in the instructions for compensating for heat or something. Also attaching physical images of the shunt.


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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I guess the shunt isn't wired correctly.

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jbakuwel avatar image
jbakuwel answered ·

Hi @Fredu12345,

Send us a wiring diagram.

cheers,
Jan

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