Solar panels and BVM 712

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donaldn01 asked Feb 7, '21

Solar panels and BVM 712

My RV has two 12 volt lead acid batteries (in parralel) connected to a BVM 712. I am considering using stand alone solar panels to charge the batteries in situations where generators are not allowed. The solar panels I am cosidering are 4 - 25 watt panels in series connected to a controller. The contoller has alligator style clip that are meant to go directly on the battery terminals. I know that if I do that the BVM will not see any incoming voltage and therefore be inacurate. Can I connect the Positive clamp to the battery and the negative clamp to the load side of the shunt, and then the BVM would "see" the incoming volts? Thanks for any help or suggestions.

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Stefanie (Victron Energy Staff) answered · Feb 07, 2021 at 06:16 PM

Hi @donaldN01,

not the recommended way to connect a charger with clamps to the battery or the shunt. I don't wanna talk about risk and safety. Guess you know that already. I suggest making a fixed connection with Anderson plugs. Advantage: you can easily disconnect your charger from the battery.

But to answer your question: yes, it is possible to connect it the way you want.

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Answer 1 · 2021-02-07T18:47:19Z

donaldn01 answered · Feb 07, 2021 at 06:47 PM

Yes I was going to install some type of plug to connect and disconnect the panels. I was concerned about the connection points and the monitor being aware of the "incomming" volts. I also thought I read somewhere about if clouds pass over the panels and the incomming voltage drops below the 4% tail current, the monitor assumes the batteries are full and gives a false 100% reading. Any thoughts on this?

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Stefanie (Victron Energy Staff) ♦♦ commented · Feb 07, 2021 at 07:43 PM

There is more than the tail current for the BMV to determine state of charge. For example charged voltage. If the solar charger is your only charge course, keep it high, maybe close to absorption voltage. For tail current I would start with 1% and then see how and when the BMV syncs.

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