question

svetlonio avatar image
svetlonio asked

Of two identical MPPTs, one does not charge unless reconnected

I have three MPPT chargers of which two are, as far as I can tell, identical. Same model, same configuration (using presets), same network, same firmware version, same circuit layout, same nominal PV capacity (although they are different brands).


Some days, one of them will not charge. It's always the same one ("XT PV charger"):


2024-06-20-122450.jpg2024-06-20-122420.jpg


I have a breaker between the PV and the charger. If I open and close it, it will immediately start working normally:


2024-06-20-122540.jpg


It will keep working for the rest of the day, but the following morning it may or may not refuse to charge again - I could not detect a pattern.

What could be causing this?

MPPT Controllers
2024-06-20-122450.jpg (339.5 KiB)
2024-06-20-122420.jpg (281.8 KiB)
2024-06-20-122540.jpg (305.0 KiB)
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2 Answers
Justin Cook avatar image
Justin Cook answered ·

Two questions: what breaker do you have between PV and charger, and, when the charger says "State Off" as it does in your second screenshot, there will be a link below it that says "Why is my charger off?"

Click that, and tell us what it says.

why-is-the-charger.png


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svetlonio avatar image
svetlonio answered ·

As you can see from the screenshots, there is no link or explanation - it's just "off". (That text does appear when I disconnect it, but not when it acts up). Another odd thing about it is that the total network power is shown as 0 - it doesn't appear to "see" the other MPPTs.

The breaker is a copy of the breakers in front of the other, working, MPTTs, so not a factor - they are all set up in the same way. (If you must know, they're all proper DC breakers from midnite solar).

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Justin Cook avatar image Justin Cook ♦♦ commented ·

Excellent, the MidNite Solar (CBi OEM) breakers are definitely appropriate. Try removing the offending MPPT from the VE.Smart Network it's connected to and see if that gets it to start up again.

VE.Smart Networking, while a super neat little feature, has in my experience proven to be rather temperamental - as indeed I sooner or later find all BT mesh networks to be. They're super handy when they work, but occasionally need a bit of prodding.

If the controller does indeed start behaving normally again after you've removed it from the VE.Smart Network, the next thing I'd try is fully deleting the whole network, removing the controllers and the BMV, and then re-create a new one from the BMV and rejoin the new network from each of the controllers - basically a full network refresh.

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svetlonio avatar image svetlonio Justin Cook ♦♦ commented ·

I will try, thanks for the suggestion! I think at least some of the network is working since it shows temperature from the BMV. This looks like a firmware bug to me, but to be fair it could very well be triggered by oddities in the network.

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