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rockb avatar image
rockb asked

MPPT 75 | 15 Bluetooth No Voltage

I just purchased a travel trailer that came with a MPPT 75 | 15 and 250 watts of panels. I installed the app and it reported no voltage. I put my multimeter on the two wires going into PV+ PV- and it read 0V. I contacted the dealer and dropped it off. Over a month later they say come pick it up they have replaced the charge controller and all is good. Report states "PANEL PUTTING OUT 33.7 AT PANEL, 33.7 AT CONTROLLER CHARGE SIDE INTERMITTENT AND NOT SHOWING DATA ON APP SIDE CORRECTION:NTO CONTROLLER". I get it home and I am getting the exact same thing 0V on multimeter to PV+ PV- wires and app showing 0 V and it is currently full sun at noon in Florida.


Battery is full but I would expect that the panels should still be putting out voltage even if the battery is full or am I wrong?

voltage
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2 Answers
derrick thomas avatar image
derrick thomas answered ·

Have you taken a voltage reading with the pv disconnected from the MPPT?

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rockb avatar image rockb commented ·
I have not. Will do that this afternoon and relay the results. If things are operating normally should that make a difference?
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derrick thomas avatar image derrick thomas rockb commented ·
Yes it will make a difference. If you have no voltage on the pv cables when disconnected from the MPPT that shows that there is a problem with the panels or the cabling from the panels. First I would make sure any disconnects or fuses between the panels and the controller didn't get left disconnected by the service center.
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seb71 avatar image seb71 rockb commented ·
Besides the PV voltage, also check the polarity (which PV wire is + and which PV wire is -).
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derrick thomas avatar image derrick thomas seb71 commented ·
Yes good catch. I work with high and low voltage so often that my brain just automatically looks at polarity without even thinking about it so it didn't even occur to me to write it in the response.
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rockb avatar image
rockb answered ·

So I went out and removed the PV wires from the controller and tested. Meter showed -38 volts. I suspect that the folks at the dealer hooked the new controller up the same way that Keystone did but did not fire up the app to make sure that the controller was getting proper voltage.

When I plugged the PV+ wire into the controller port marked PV+ and the PV- wire into the controller port marked PV- I can read voltage with my multimeter at the controller and the Victron app shows wattage on the panels.

I bought a new trailer so I would not have to troubleshoot things like this myself but I guess that is the way the world works now.

Thanks for the assistance.


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