question

andrew7 avatar image
andrew7 asked

MPPT 100/50 No Watts No Ampers currently 62V

Hi All, we have recently (about a month ago) had an additional 350W solar panel mounted onto the roof of our caravan.

So now a total of 2 x 150W and 1 x 350W connected in series with a Victron MPPT 100/50 Controller to a 200AH Lithium Battery.

On August 9 no lights showing on the controller and unable to hook up with the iPhone app.

Tried many things but in the end, disconnected the Battery then PV Positive leads then reconnected after a minute or so. Once reconnected the lights came on and immediately went to Float, phone app also worked.

As you can see its been working up until the last 2 days, Voltage output remains the same but 0 Watts and Amps.

Also, have a 30 amp mains power charger set to lithium, I have tried turning that off but makes no difference.

Currently in southern Australia and the sun is low in the sky with many overcast days as you can see in the history

Tried a factory reset via the app but still no good.

Any help you may have will be greatly appreciated.

MPPT Controllers
photo-10-8-19-3-49-18-pm.png (69.1 KiB)
photo-10-8-19-3-49-33-pm.png (110.9 KiB)
photo-10-8-19-3-50-43-pm.png (92.8 KiB)
blue-solar-history.jpg (144.0 KiB)
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3 Answers
klim8skeptic avatar image
klim8skeptic answered ·

Battery voltage of zero? Check the charge controller terminals for battery voltage, your likely to have a blown fuse/circuit breaker.

"now a total of 2 x 150W and 1 x 350W connected in series"

All 6" celled panels? 144 cells total in series?

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JohnC avatar image
JohnC answered ·

Hi Andrew. Without knowing what your Li batt/BMS is, it's possible that the batt is isolating itself from further charge. Your history shows some strange behavior with the charge times, but this may explain it. Having another charger paralleled in may just be exaggerating this - and make it harder to diagnose.

The registered zero batt V might be happening just from your 'resets', so maybe not a big deal.

And yes, your panel wiring may need a little work to optimize, but that's likely a separate issue.

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andrew7 avatar image
andrew7 answered ·

Thanks for your replies.

I am quite a novice at this, after more investigating found it was a blown 20 amp fuse I am guessing between the controller and battery. (because it all fired up once I replaced the fuse).

Not sure if I can increase fuse to 25 or 30 amp, I think its a 6mm wire.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

2 days ago you had 395W PV-power -> around 30A charging current -> so you have to increase the fuse size or it will blow over and over again. You should use at least a 30A fuse.

I'm not sure but I think it's not recommend using different sized panels in one string at the same MPPT.

By the way what kind of battery do you have? Normally a 12V lithium battery has an absorption voltage at 14.2V but at you screenshot there are voltages up to 14.8V.

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JohnC avatar image JohnC ♦ commented ·

A blown fuse would explain your immediate issue, but you shouldn't really be 'guessing' this stuff. Your mppt is good for 50A, so are your panels. The mppt has terminals specced at 13mm2/AWG6, and if they're not overly long that's perhaps what you should be using. A 60A fuse might be more suitable.

That said, I think you need to further investigate your panel setup. Your figures don't confirm them in series, and if they were would likely blow your mppt. They're not matched, so an optimum system may not be possible, but maybe can be improved upon. If you can provide the Vmp of each panel we may be able to help with that.

Also, full days in Float with little Wh contribution suggests either full batts or a dominating influence of an alternative paralleled charger. How you deal with this is up to you, but it's likely your pv could be handling much more of the load. And the app will make more sense.

Please don't despair though, tis just a matter of getting your head around it all. :)

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