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daves avatar image
daves asked

MPPT 75/15 not charging

Hi, I have a 150w solar panel on my van connected to MPPT 75/15 charging 2 AGM batteries.
All was working well before the winter, now not charging. Checking the voltage directly from the panel 27v, voltage at the end of the cables disconnected from the MPPT 27v, connected to the MPPT (checked across the screw terminals) drops to 13v. All fuses including the 20a at the bottom of the controller are ok, all battery connections also ok.

Is there anything else to look for or could this be a controller or solar panel fault? All ideas welcome. Thanks

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MPPT Controllerssmart solar charging behaviour
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4 Answers
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gigabert answered ·

Hi, what are the panels specs? Uoc, Isc, ... Can you measure the Isc of your panel? at daytime in the sun of course ;) gig

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daves avatar image daves commented ·
Hi, thanks for the reply, the panel is a FlexiSun 150w, I believe it has voc 30.11v and Isc 6.3A. If we get some more sunshine soon I will check the Isc. and report back
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daves avatar image
daves answered ·

@gigabert I have checked the Isc at the panel and am getting 1.44A, the voltage was 27.3. Does this mean I have a faulty panel? Dave

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klim8skeptic avatar image klim8skeptic ♦ commented ·
If you short the panel you will have a current reading, but the voltage will be zero.
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daves avatar image daves klim8skeptic ♦ commented ·
What I have done is disconnected the leads from the panel, put my volt meter across to measure 27v, then swapped my meter to amps and got a reading of 1.44amps.
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klim8skeptic avatar image klim8skeptic ♦ daves commented ·
With good sun and angle Isc should be close to spec.

With good sun and angle Voc should be close to spec.

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gigabert avatar image
gigabert answered ·

looks like your panel is not delivering as it should according to specs.

Dismount and check ingredients of the terminal box on the back of it, maybe you can open it and check the connections, diodes etc. you might split up and check the strings individually.

Let us know, send pics if possible.

Good luck


Gig

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midwalest avatar image
midwalest answered ·

I have the same issue. I am NOT an expert and would like idiot proof advice please!!

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Related Resources

MPPT Product Page

MPPT Error codes

MPPT 150/60 up to 250/70 Manual

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