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Nick Chandler avatar image
Nick Chandler asked

BlueSolar MPPT 100/30 stops charging

Have a 100/30 hooked up to two 175W panels. Been using it fine for about a month now. Out of the blue, it has stopped working. It charged the batteries up to 92% and then output 0W (sometimes 2-3). I unplugged everything and replugged it back in and it worked as normal again for a few hours (edit: got me up to 96%). Then back to 0W (still reading a nominal amount of V both from the battery and from the panels). I unplugged and replugged again, this time it worked for a few minutes. But then stopped. I repeated the process and now it's not charging at all.

I have checked all the connections with a multimeter and everything appears tip top. One thing I noticed is the voltage reading from the battery terminals of the controller do not match the voltage reading from the batteries themselves.

I also wondered if it was my battery monitor being wrong, but when I turn appliances on, the charger still refuses to output any wattage. Is my unit defective? Or is there something else I should try that I'm missing?

MPPT Controllers
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Hi Nick,

You don't mention any voltages, charge controller led status, battery type, charge controller battery settings, etc.

"One thing I noticed is the voltage reading from the battery terminals of the controller do not match the voltage reading from the batteries themselves"

Could be the wire between controller a bit thin, or loss through a fuse/breaker.

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Nick Chandler avatar image Nick Chandler klim8skeptic ♦ commented ·

My apologies.

Batteries are vmax AGM deep cycle. Two 155aH hooked up in parallel.

I'll upload the battery settings here too.

The two panels are hooked up in parallel. Right now I'm getting 40.78V with a V Max today at 44.18 from the solar and reading at 13.8V to the batteries, When I first reset the controller it starts in bulk, but quickly switches to float. Currently it's hovering at 3-4W while in direct midday sun.


The wire from the controller is 8AWG and goes about 18" to the batteries.

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Nick Chandler avatar image Nick Chandler Nick Chandler commented ·

Pictures from Victron Connect

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Nick Chandler avatar image Nick Chandler Nick Chandler commented ·

I mentioned the panels being hooked up in parallel, they are not. They are two 12v in series. I'm juggling too much on my mind at once right now, sorry about that.

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wkirby answered ·

How old are your batteries Nick?
The graphs show that on one occasion they managed to get the battery from 10.72V (very deeply discharged) to full charge 14.5V with just 40Ah. It should have taken more than 2KWh to do that into a healthy battery and that should have taken several hours..
The reason it's goes to Float sooner that you'd expect is because it is reaching its target Absorb Voltage quickly. The batteries are simply not absorbing the ammount of energy that they should be.

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Nick Chandler avatar image Nick Chandler commented ·

They are very new, installed just a month ago with the controller. According to my battery monitor they have never gone below 70%. Does that suggest my battery monitor might be faulty which is causing me problems down the line with the batteries themselves?

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wkirby avatar image wkirby ♦♦ Nick Chandler commented ·

You mentioned that you are measuring a Voltage difference at the battery terminals and the controller. The larger the difference, Voltage drop, the more resistance there is in the wiring between the two. There will always be a difference depending upon the magnitude of current flowing through this wiring, but if there is a big difference then you'll experience the problem that you're having..You should notice no difference at night when there is no current flowing from (or to) the charger.

Is your wire size correct? Connections good? Fuse holders making good contact with fuses? These sort of things need to be checked yourself. A multimeter won't pick up these type of faults using continuity or Ohms mode.

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