Can An MPPT Fix Itself?

[AgroVenturesPeru]

TLDR: troubleshooted MPPT remotely with an engineer from this website last year. Conclusion: unit bad/miscalibrated, send to distributor for warranty replacement. Instead of doing this, I just bought a new unit and stuck the old one in a box for ten months. Recently, I sent the old unit to a distributor, and they report that nothing is wrong with the unit.

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Last year, I posted about the problem I was having with my system, and a very knowledgeable member on here came to the rescue. He really went above and beyond to help me, and concluded that the problem was caused by a faulty 250/100 MPPT, which reported voltage roughly 3V higher than every other instrument inlcuding multimeter. A video we took showing this discrepancy:

Since the company I bought the unit from acted pretty shady post-sale, I decided to just go ahead and buy a new unit. I learned my lesson, and ordered off of Amazon USA this time, instead of one of the distributors in this country. I figured I'd rather deal with the international shipping than deal with the lousy cusomer service here. We disconnected the old, glitching unit, stuck it in its box and put it in a drawer, where it sat for the past ten months, meanwhile we installed the new one. It's been about ten months now, and it's been nothing but smooth sailing with the new unit. We didn't make any modifications to our system other than swapping out the MPPTs.

A month ago, my wife and I decided we need to do something with the old unit. Tackling this topic has become akin to unmedicated molar extraction, so we weren't eager. There were only a couple other options available on the V distributor list, beside the company that sold it to us. A couple companies were out of the question, because they just didn't want to deal with the hassle (really honoring their distributorship). We found one that was serious and sent the unit to them at the end of February.

They basically sat on the unit for three weeks, and we periodically checked in, and they mostly ignored our messages. Just yesterday my wife asked what was going on, and they responded that they were done with the "tests" and would send us the report that afternoon. Wow what a coincidence, the same day my wife asks, is the same day they conclude their tests!

Long story short, we received the report and it says the unit was fine.

Not sure if this detail is relevant: The V Pre-RMA bench test instructions say to connect to a 24V battery on the PV side and a 12V battery to the battery side, but their report says they connected to a PV array and an inverter, and shows some VConnect screenshots with input voltage 111V +. But who cares what the instructions say, anway. No photos or videos of their tests, but whatever.

I sent them the same video clip that I linked above and asked them the same thing that I will ask this forum:

How is it possible that the MPPT fixed itself by being in storage for ten months?

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I'm thinking about putting the unit in my carry-on, since I'll be travelling to visit family in Florida in a couple months and looking for a distributor stateside to test the unit. What do you think? If the US distributor says there's no problem, I guess I can just hand the unit off to my folks who live in California and they can work on re-selling the thing. Technically it only has three years of use, and I guess it will still have one more year of warranty left on it for someone who wants to take the gamble. Maybe one of the distributors would be willing to put their money where there mouth is and buy the unit, since they think "the unit is fine."

Do you think customs in the US will hassle me for having an MPPT in my carry-on? Do you think airport security in Peru will want me to confiscate the thing before boarding the plane? It's worth about a grand new, but this one is used obviously. Not sure how that would affect airport/customs shenanigans.

 

[robby]

That is the problem with buying equipment and shipping it abroad. You need to know before hand what kind of Custom duties and what over weight fee's the airline might charge you.
From what I have been told most countries do not have Customs duty on Solar Equipment so you might be fine with that. Double check because if there is duty it might mean taking it with you in an unknown condition would be a bad idea financially. Then you have to see how much the Airline will charge to carry it. They typically have a Weight vs Dimension pricing system and which ever one is higher is the one they will hit you with.
As for Customs, they will not have an issue with it being carried on the plane. It is only batteries that they have a problem with.

 

[kommando]

How is it possible that the MPPT fixed itself by being in storage for ten months?

An intermittent fault that only appears after an extended time will test good after 10 months rest or maybe the 10 months rest flushed out the 3v variance like a ECU reset on a car.

 

[teal95]

Test it yourself by swapping back out with the one you have. No verification can be as good as putting it back in service.

 

[AgroVenturesPeru]

An intermittent fault that only appears after an extended time will test good after 10 months rest or maybe the 10 months rest flushed out the 3v variance like a ECU reset on a car.

That actually does sound feasible to me. Do you have any firsthand experience with charge controllers working themselves out?

Obviously the problem is a PITA, because the glitch will more than likely pop up again in the future.

 

[kommando]

Do you have any firsthand experience with charge controllers working themselves out?

Not with charge controllers but I have seen some odd self fixing bits of kit over my 50 years of fixing broken kit. I am now of the mind that anything can happen and not to discount the impossible until you have tried and proved its impossible.

Intermittent faults are the hardest to fix and at the same time the most annoying and confidence busting. At least you have a spare if it goes again and I would take the V starting to read high as the time to changeover not the final fault.

 

[AgroVenturesPeru]

Test it yourself by swapping back out with the one you have. No verification can be as good as putting it back in service.

I don't plan to ever have that charge controller come back to the house. If I hook it up again here and it works, it won't make me feel any better, because nothing has been done to fix the original problem. If it does act up again, then the manufacturer would just argue that the problem is with the installation instead of the unit.

That is the problem with buying equipment and shipping it abroad. You need to know before hand what kind of Custom duties and what over weight fee's the airline might charge you.
From what I have been told most countries do not have Customs duty on Solar Equipment so you might be fine with that. Double check because if there is duty it might mean taking it with you in an unknown condition would be a bad idea financially. Then you have to see how much the Airline will charge to carry it. They typically have a Weight vs Dimension pricing system and which ever one is higher is the one they will hit you with.
As for Customs, they will not have an issue with it being carried on the plane. It is only batteries that they have a problem with.

The plan is to take it to the USA. So you're confident the USA doesn't charge duties on something like this? It would be crazy since the thing is used and not even in its original packaging. I'm not worried about the weight/dimension thing, because it's just a charge controller, not an inverter.
Makes sense to me about the airline not having an issue with it.

The thing I'm not sure about all this is the willingness of a V distributor in the USA to test a unit that was purchased abroad. Most of the distributors here weren't even helpful when the unit was purchased from a competitor in the same country.

 

[AgroVenturesPeru]

Not with charge controllers but I have seen some odd self fixing bits of kit over my 50 years of fixing broken kit. I am now of the mind that anything can happen and not to discount the impossible until you have tried and proved its impossible.

Intermittent faults are the hardest to fix and at the same time the most annoying and confidence busting. At least you have a spare if it goes again and I would take the V starting to read high as the time to changeover not the final fault.

Well it certainly wasn't "intermittent" when we had it here. The thing deviated further and further over the course of about one year, before our battery capacity was reduced to around 25% and we finally decided to buy a new MPPT, and unhook the bad one. Before swapping them out, we did disconnect the unit periodically when troubleshooting, so why wouldn't the thing have resolved itself after 10 minutes of being disconnected, yet only after 10 months?

Do you think there's anything that the distributor might have failed to do properly that could have prevented them from seeing the problem? The screenshots they sent demonstrate failure to follow procedure, yet that is nitpicky in my opinion. But maybe that's an important detail after all?

Personally, I don't rule out foul play, after some of the messages I received from the V sales rep from this part of the world, as well as the experiences shared by other members in my other thread on diysolarforum.

 

[kommando]

I don't have much faith in 'Professionals', they cover too many variants plus all the annual changes to know it all that's needed to fix it all and have an eye on the bottom line too. I buy second hand, cheap if it goes wrong and also old enough to be fixable by myself. If I buy new I buy off Amazon or someone else who will take back goods no questions asked and send it back at the first sign of problems.

 

[AgroVenturesPeru]

I don't have much faith in 'Professionals', they cover too many variants plus all the annual changes to know it all that's needed to fix it all and have an eye on the bottom line too. I buy second hand, cheap if it goes wrong and also old enough to be fixable by myself. If I buy new I buy off Amazon or someone else who will take back goods no questions asked and send it back at the first sign of problems.

Sounds like a good MO to me.

 

[Dave911]

Equipment can be erratic. Manufacturers of control equipment oftentimes put the devices in environmental chambers and monitor performance will changing the temperature as part of the burn in testing.
Many distributors are not technical and have very limited test equipment. If they do, I doubt they will test it for free. If you didnt buy it from them they likely have no obligation to service it.