Author Topic: U Power 8kw 24 volt Faults  (Read 1563 times)

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Offline Pete

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U Power 8kw 24 volt Faults
« on: September 03, 2020, 07:56:44 pm »
I recently changed my solar system over to a 24 volt system.
I bought a U Power ( basically a PowerJack ) 8 Kw, 24 volt inverter. To power my system.
I picked the inverter up when I took it out of its packaging and heard a rattle.
So I took the covers off, and found that one of the screws that held the mosfet board had fallen out. So I figured that transporting it from China may have rattled it loose but suspecting it was never tight enough in the first place. I checked all the other screws and they were fine.
So I installed the inverter.
Switching it on it worked as expected. That is until I turned my 240 volt circuit breakers on. Then a voice from the inverter informed me that I had a 70% load. That seemed odd as only very light loads were on.
I checked the shed circuits and pulled the plugs out of the power sockets. Then tested the power points, still 70% load.
I checked the inverter without anything plugged in and found that the Active and Neutral were crossed up. Which meant that my MEN system and safety switches would not work and were effectively earthing out the Active rather than the neutral wire.
So I took the inverter apart and found that some lunatic at the factory had connected the Neutral wire from the power socket and terminal block to the Line Out on the inverter circuit board. And of course the Active was connected to the N out point.
I swapped them over after making sure that my brain was still working and that the markings were actually correct on the boards.

Then I looked at the circuit board that the wires connected to and saw that it was resting on the Transformer metal mounting bracket and that a very dodgy circuit board mount had come off . The other end of the board was tucked under the transformer bracket.
This meant that when the board was incorrectly connected that the Active wire was earthed to the frame of the inverter.
So I replaced the circuit board standoffs and put one on both sides of the transformer bracket and used cable ties to mount the board properly.
Then I found that a ribbon cable from the switch that is used to turn the inverter on was hanging out of its socket and the switch only worked sometimes. So that was re seated.
Finally the inverter is working properly and my safety switches are operating correctly.
As others have mentioned before BEWARE CHINESE INVERTERS.

Offline Pete

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Re: U Power 8kw 24 volt Faults
« Reply #1 on: September 04, 2020, 02:35:26 am »
When you look at the first photo you can see the scorch mark to the right of my thumb, that is where the power out board was arcing to the transformer bracket.
Here is a photo of the mixed up active and neutral connection on the same board.
Why they fitted that board without any real support on one end is beyond me. But to mix up the active and neutral is just inexcusable.

Offline dochubert

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Re: U Power 8kw 24 volt Faults
« Reply #2 on: September 04, 2020, 10:34:42 pm »
Hi Pete,
I should be surprised but I'm not that powerjack is still wiring them that way.
From my post about my own Upower adventure;

Quote
This was advertised as split phase,but was not wired correctly for output.  Craziest wiring I've seen yet on one of these (this is my 5th powerjack).  Someone not expecting issues would have trouble getting 240/120v connected for running a house.
The center tap/neutral of the xfmr was wired to the L1 input of the control board and was monitored by the hall sensor for the lcd screen.  Then L1 output from control board went to the resettable breaker and to all L1 output connections.  The real L1 lead from the xfmr was connected as the neutral.  That will work fine for someone just using 120v but talk about non-standard!  The L2 lead from the xfmr was connected to the battery fuse and then to the L2 output connector.
That means the input for the battery charging function is not fused at all.  Not important to me as I don't use the battery charging function and just disconnect it on all my units.


Sound like yours?
I rewired mine correctly.
I also had to improve cooling.
Hope you're having fun!
We're all going to DIE!  (eventually)

USA = Communist former republic
---  dochubert --

Offline Pete

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Re: U Power 8kw 24 volt Faults
« Reply #3 on: September 05, 2020, 01:26:40 am »
Hi Doc, yep sounds like they are using farmers to put the boards together.
Mine had clear markings on the output board that said, L out, and N out. But some lunatic put the black wire onto the Line out and the Red wire to the Neutral connection.
Then there was the output board that just floated in the air at one end, it had a stick on circuit board standoff that had slid down the transformer bracket and allowed the board to short to ground. Somehow it did not blow the inverter up.
The inverter has a quality control sticker on the bottom which said pass. I guess it may pass when just tested to make sure it outputs a voltage when a battery is connected to it. But having line voltages on the neutral does not go well with an MEN system that uses Residual Current Devices for safety. Nor does switching the Neutral at power points, which was the case with the neutral and active mixed up.
Outright bloody dangerous stuff.
I guess that is why they don't actually put their names on the inverters or have a website where they can be contacted.
I am only guessing that U Power and PowerJack are the same company as the inverters look identical.
Hope all is good over there Doc.
It is fortunate that we have just enough knowledge to repair the inverters before we use them isn't it.
Cheers
pete

Offline Pete

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Re: U Power 8kw 24 volt Faults
« Reply #4 on: September 06, 2020, 03:18:07 am »
Another issue with these inverters is the outrageous ratings they give them.
From the spec sheet in the manual the biggest load that they say that the inverter will run is only around 3kw. Less for some loads.
So what they sell as an 8KW inverter is actually only a 3kw inverter.
I read somewhere that the 8Kw is a 1 second rating
and the 20kw is a 1ms rating.
Pretty useless way to rate an inverter. Fortunately none of my loads are bigger than about 1600 watts and I only try to run one of them at a time.
Oh well you get what you pay for eh
Pete

Offline dochubert

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Re: U Power 8kw 24 volt Faults
« Reply #5 on: September 06, 2020, 03:13:00 pm »
Hi Pete,
So, more than a year since I bought my Upower 15kw and yours is proof they are still wiring them in that screwy way.

My 7 year old 24v/8kw pj runs my water heater in powersave mode.  When on it draws about 2500w at 110v and does fine.  The wh elements are rated 4500w 240v.  I first tried 220v for it but the inverter would not run more than a minute at 4500w/220v.  Hence running at 110v.  Takes longer to heat up the tank but runs reliably like that.
The point is you get less than half of powerjack's rating as a useful limit.
For the price its still a good deal.  Usually.

While still in San Diego, I used to run that 24v/8kw to run my house (240/120) on sunny days.  It would do fine up to 3kw or so and a bit over for a few minutes.  Yours should be fine for what you are running.  You may want to add some cooling on the transformer, or just remove the bracket, plate, rubber pad and bolt from it to improve cooling.  Unless you need it to be portable...

We're all going to DIE!  (eventually)

USA = Communist former republic
---  dochubert --

Offline Pete

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Re: U Power 8kw 24 volt Faults
« Reply #6 on: September 07, 2020, 03:57:17 am »
Hi Doc, I have my inverter mounted on its side so I can see the screen. So taking the bracket off the transformer won't work.
I only plan to run a 1600w air compressor rarely and a1500w Woodsplitter sometimes too. The woodsplitter will probably only do an hour or so between me needing a break . I guess I will find out how warm the inverter gets.
The transformer looks pretty large so hopefully it won't be that inefficient that it will get too hot.
My U Power inverter came in a box that had Made in China printed all over it. I thought that PowerJacks were made in Taiwan so my guess is that the Chinese have cloned the PowerJack and are using a labour force that are not very technically minded.
Anyway the inverter is working, I haven't tried big loads yet, but am happy that I found the problems and sorted them before it became an expensive smoke machine.
Hope the new batteries arrive soon and get you sorted for the coming winter.
Our days are getting longer now so our batteries are charged up again well before lunch time.
Cheers
Pete