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stefan-archer avatar image

Victron MPPT 75/15 Low PV Voltage Reported - Won't Charge

When I test the voltage at the controllers terminal screws it shows 66V (I'm using 3x 20W panels in series) - In the app its only showing 12.7V; which means my 12V batteries won't charge. If I connect each individual panel to the controller it still shows 22V at the terminal but still only 12.7V (each one shows the same) in the app. Is my controller toast?

MPPT - Solar Charge ControllerBMV Battery Monitorvictron
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20W panels? Is this a typo?


Where it "shows" 66V/22V? You mean that is what you measure with a multimeter or is something you see in VictronConnect?

Not a typo - I have 3 small 20W panels in series. The number 22V is referring to the voltage tested with a multimeter at the screw terminals on the mppt controller - 66V is the voltage at the screws when I have all 3 in series. Victron Connect is showing ~12.7V for PV and ~12.8V for the Battery.

3 Answers
klim8skeptic avatar image
klim8skeptic answered ·

you have a bad/high resistance connection on the pv wiring.

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Turns out all 3 of my 20w panels are dead - not sure how... but replacing them with a new panel did fix the issue.


Thank you!

dazey77 avatar image
dazey77 answered ·

Is the 12.7v it shows in the app the same value as it has for the battery? If so I don't think its seeing the panels at all. You could try it with the battery disconnected, it should operate with no battery if panels are connected. My experience with that unit is that with a blown fuse, it won't power up at all.

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The 12.7v PV in the app is slightly lower than the ~12.8v the app is showing for the battery.

Stefanie avatar image
Stefanie answered ·

Hi @Stefan Archer,

did you check the fuse of the 75/15? Maybe it's blown.

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It unfortunately was not the fuse - fuse was fine and I tested with another fuse just to be sure.