A little help


Advanced Member
Mar 7, 2018
Turned on the camper refrigerator yesterday and seemed like for a nice sunny day the batteries weren't charging. Solar panel was producing 0w and the BMV 712 was flashing charge. Plugged it in overnight. Found a blow inline fuse from the shunt and replaced it. Batteries were fully charged overnight and when I unplugged it this morning there was little sunlight but the panel was showing 1-2W. Started loading the refrigerator which is drawing more power since I'm opening and closing it. It's early but there's sun hitting the solar panel and it's at 0w. Would this be because because the PV isn't exceeding the battery volts by 5v? My batteries are two 6volt AGM's. Whole system was new installed in 2020.

I did have the kill switch on all winter and powered the system up a few days ago. Looking at the history it seems to have been generating enough watts to charge the batteries. Power tested at the panel cables is 24 volts so it's generating power.

PV voltage at the MPPT input is 13.02, which seems like a problem but doesn't explain why briefly this morning there was 1-2w at the panel.


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your batteries are fully charged. The MPPT won't send additional charge their way, so zero watts from the PV. Discharge the batteries and try again?

The shunt fuse blew? (small glass inline fuse?)
Thanks for the reply Vic. The little 1amp glass fuse did blow.

I ended up rechecking the panel as the volts from the pv to mppt weren’t matching up. Turned out I could get the panel to show 24-25 volts but as soon as I plugged it back in to the camper they’d drop to 13. Ended up being the device that the power from the panel goes through and sends to the cord/plug was bad, if I wiggled it the volts would vary 24-13.

I’m 1.5 hours from the factory so I drove there and picked up a new panel, they still had some 160 watt panels. Took it home, installed it and batteries were getting a charge, great watts/volts from the panel into the MPPT.

The screen shots above don’t really give a good picture of what was happening, the only clue in them to me was that the voltage from the solar was 13.61 even though the meter read 24 when I tested the panel, that’s what made me recheck the panel and discover the above mentioned issue.
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