Battery not reporting correctly

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Shane Terpstra asked Jun 3, '21

Battery not reporting correctly

I have a strange issue, which is probably just me not knowing...

I have a BM-712 and MPPT 100 Solar Controller installed in my camper to a couple 165W solar panels. The system is basically wired like this (https://community.victronenergy.com/storage/attachments/4583-screen-shot-2019-07-29-at-93141-am.png) without the Color Controller. This past weekend, the voltage of the battery was reporting ~10V but the charge was showing 100%. When the sun came up and the solar started to work, the charge would go up throughout the day. I also used shore power through a generator to augment the charge. As soon as I unplugged the generator, the battery went back down to ~10-11V. I connected a NOCO trickle charger and it was at 25%.

Today, I pulled the battery out completely to recondition. The BM-712 showed 13V. The solar was still connected. I would have expected that, since the BM-712 is only monitoring the battery, it would show only battery voltage and not any solar charging. Of course once I turned off the solar breaker, the BM-712 went to zero.

My questions: How can I get the correct percentage to report on the BM-712 and why would a voltage show on the BM-712 with no battery connected?

battery charging MPPT SmartSolar

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Answer 1 · 2021-06-03T03:48:38Z

klim8skeptic answered · Jun 03, 2021 at 03:48 AM

"Of course once I turned off the solar breaker, the BM-712 went to zero."

Zero volts?? That would be a blown fuse/circuit breaker between battery and bus.

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Answer 2 · 2021-06-05T14:03:42Z

Shane Terpstra answered · Jun 05, 2021 at 02:03 PM

There’s no battery hooked up so zero volts is what I would expect. The part I don’t expect is when there is no battery hooked up, MPPT on, the BM-712 is showing voltage. My understanding was that the BM should only display battery statistics, not solar statistics.

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klim8skeptic ♦ commented · Jun 05, 2021 at 05:09 PM

"The part I don’t expect is when there is no battery hooked up, MPPT on, the BM-712 is showing voltage."

All perfectly normal, the mppt is a regulator after all.

Just dont expect the output of the mppt to be stable (without a battery) as clouds/loads come and go.

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