question

hellie80 avatar image
hellie80 asked

MPPT 75/15 not charging

screenshot-20230707-115907.jpgMy solar panel/MPPT controller/12v battery set up was working perfectly on my van...until it recently wasn't!

I seem to remember upgrading the firmware recently but don't remember exactly when. Wondered if this might have something to do with it?

When connected to Victron Connect I can see that the charger is off despite the sun being out strongly and the fridge being on. I would have usually seen a bar graph with bulk, float and absorption showing, but now only have 10wh showing every few days.

I'm not an expert by any stretch of the imagination but have checked all cables, voltage going to battery, voltage of battery, fuse etc and there's nothing obvious.

Any suggestions of what's the fault?

I have attempted to search for similar queries in the forum but have failed to find anything that seems the same or that I really understand so I'd be ever so grateful for any assistance.

Thanks

H

MPPT Controllers
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Paul B avatar image Paul B commented ·

not enough info we would also need to be able to help out

1. input PV voltage when the sun is out

2. battery voltage


basically check your pv conections and battery connection. and check the fuse as well

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hellie80 avatar image hellie80 Paul B commented ·

Thanks Paul

I have checked all connections with a multimeter, they're sound. As is the fuse.

Screenshot of battery and solar voltage - does that assist?

Helenescreenshot-20230626-191735.jpg

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nickdb avatar image nickdb ♦♦ hellie80 commented ·

You either have a faulty panel, bad connection, no sun or the world's largest pigeon is on your roof..

The Panel is producing 10V which is 2V below the battery.

The MPPT needs battery plus 5V to start working, so until your panels produce 17V nothing is going to happen.

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3 Answers
mvas avatar image
mvas answered ·

Can you check the Voc ( voltage open circuit ) of each and every solar panel independently? Is one panel very different?

Can you check the Isc ( Short Circuit Current ), of each solar panel, under good sun?

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hellie80 avatar image
hellie80 answered ·

I have 1 160W panel.

Not sure how to check the Voc or Isc...but will find out and try that.

Unfortunately not overly sunny today but there's definitely no mega pigeon sat on the panel!!

Also, have plugged the van in to the mains for 24hr and it doesn't seem to have charged the leisure battery either....so I'm even more stumped.

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nickdb avatar image nickdb ♦♦ commented ·

Start by checking all the wiring and connections for anything that is loose or looks iffy.

You will need a trusty meter and go and measure across terminals, across panels when disconnected from the charger etc.

Have a look here:

https://www.youtube.com/watch?v=eh6hzMb69gY

It is also worth looking at the panel specs to see what Voc and Isc is supposed to be - this can often also be stuck on the back of the panel, or just use the power of google if you know the model number.

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hellie80 avatar image
hellie80 answered ·

Thank so much to you all for your answers so far. Will try your suggestions and report back :-)

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kevgermany avatar image kevgermany ♦♦ commented ·
Could be an intermittent break in the cables from solar to MPPT.
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