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benjaloid avatar image
benjaloid asked

Solar Victron MPPT charge issue

I’ve seen some similar posts on this topic and done some searching but I can’t seem to find anything too helpful. My setup was working great and then stopped so hopefully someone can help shed some light!

I have a simple setup in my t5.

100ah agm, victron MPPT, victron bat monitor, durite split charge, led lights, 12vfridge. Pretty basic.

Solar has seemed to be working really well since install but last weekend I went away, it was a very hot one and the fridge was on the whole trip. I noticed the battery had run itself down to 45% and figured that was weird since there was so much energy for my panel to suck up. I then noticed that the blue light on the MPPT was flashing which I have learned means there is power to the unit but it’s not charging the battery. The app shows 0W and doesn’t seem to be charging my battery anymore. I have checked the fuse on the unit and the inline fuse but both are intact and nothing else seems out of place.


Ang help or thoughts would be really appreciated. Thanks.

solarvoltagesmart solar charging behaviour
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kevgermany avatar image kevgermany ♦♦ commented ·
Which MPPT?

Please post a screen shot of the battery settings in the MPPT as well as the initial display when you connect.


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benjaloid avatar image benjaloid kevgermany ♦♦ commented ·

thanks for your reply! It is a 75/15



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ccf6beba-3d79-4c45-a736-ce41a1a46263.png (1.5 MiB)
klim8skeptic avatar image klim8skeptic ♦ benjaloid commented ·
Post a screenshot of your detailed history also pls.
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benjaloid avatar image benjaloid klim8skeptic ♦ commented ·

But it is extremely inconsistent and when I checked my battery most recently it was under 12v so I’ve had to trickle charge it. My understanding is that the mppt and victron connect should at least be reading some incoming watts but I’m always seeing 0w even in full sun

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6540064f-4a3b-47b5-9f66-adaa1da572d7.png (370.6 KiB)
andy-h avatar image andy-h benjaloid commented ·
Yesterday your panel vmax was 20.24.. What's it been today.

I think you are getting the same issue as me....

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benjaloid avatar image benjaloid klim8skeptic ♦ commented ·

3ccbbdb8-53fb-4144-8cec-866533737b18.png

Another screenshot showing history.

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3ccbbdb8-53fb-4144-8cec-866533737b18.png (249.6 KiB)
4 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

In general the 'bulk' light flashing on the MPPT means that it is in 'night' mode - insufficient PV voltage to start the unit. The PV voltage needs to be V bat +5V for the unit to start operating.

first step is to isolate the PV from the MPPT, then measure the open circuit voltage of the module(s). Next is to measure the short circuit current of the module(s). Make sure that your ammeter can cope with the expected current. If all is good, then reconnect the PV to the MPPT, and check for operation and PV input voltage. If the modules are good, and the unit still won't charge, try a reset to defaults using Victron connect.

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benjaloid avatar image benjaloid commented ·
Thankyou so much for your response.


I need walking through the tests a bit honestly if you have time to help me?


I measured across the +&- of the output from the controller and that was coming in at about 12.65v at the time. I’m not sure how to perform the other tests

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christern avatar image christern benjaloid commented ·
1. Measure the voltage on the panels without the cables being connected to MPPT or fuse etc.

2. Measure the voltage at the PV connections of the MPPT.

As from the screenshots you provided the voltage of the panels is far too low (11,27V) to start charging and if the result of 1. is much higher than what is displyed in the app, then the cause is to be found after the place where you measured. If the result of 2. is much higher than what the MPPT is displaying my guess would be that the MPPT is faulty.

And I guess your battery could be at the end of its lifecycle but that is not causing this. It could rather be an effect of bad charging.

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benjaloid avatar image benjaloid christern commented ·

I am measuring 11.15at the pv connection and and 11.15 directly from the panel cables


Panel is pretty much in full sun right now. Faulty panel?

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andy-h avatar image andy-h benjaloid commented ·
If panel is in full sun with no shading, bird poo etc, then 11.5 sounds very low. Are the connections all decent and you are reading with a Digital MM
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benjaloid avatar image benjaloid commented ·
As a side note. Is it possible that if my leisure battery is problematic and on the way out this could be a possible source of an issue? Or is that generally unrelated. It seems to me I should be measuring watts on the controller even if it isn’t ending up at the battery?
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andy-h avatar image
andy-h answered ·

Is this an mppt 75/15 and did you recently upgrade your firmware


I am suspecting a similar issue to that I have if so.

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benjaloid avatar image benjaloid commented ·
I have kept things up to date yeah but I didn't notice a particular difference due to a firmware update myself
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andy-h avatar image andy-h benjaloid commented ·
Can you recall when you last upgraded firmware. Was it around 3rd or 4th September....
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christern avatar image
christern answered ·

I would say so, yes.

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christern avatar image christern commented ·

And this was a comment on "Yeah I even gave it a clean recently - its in full morning sun now. Yeah using a digital multimeter and literally just reading direct from the cables is giving me that V output. Seems it is indicative of a faulty panel? "

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klim8skeptic avatar image
klim8skeptic answered ·

I use this solar panel test for single panels.

Please dont set fire to anything..

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