Author Topic: PowerJack smoked  (Read 586 times)

0 Members and 1 Guest are viewing this topic.

Offline Pete

  • Sr. Member
  • ****
  • Posts: 357
  • Karma: +19/-1
  • Mount Barrow Tasmania
PowerJack smoked
« on: March 20, 2021, 04:19:05 pm »
Recently my 8000 LF powerjack emitted smoke. It turned out that it had blown up the Mosfet boards and the driver board.
Actually two of the Mosfet boards looked fine but I replaced them anyway.
What appears to have caused the blowup is that I had mounted the inverter on its side so that I could see the screen.
The Transformer has been affected by gravity and with the windings touching the case it has worn through some varnish on the windings and shorted to the case.
At first I thought that the blowup was caused by my circular saw jamming and that the inverter had overloaded. It has done this many times, but all those other times it just screamed and needed to be turned off and back on.
This time there was a voice from inside.
 the inverter telling me that it had problems.
When I was disconnecting the inverter I got a slight shock from the case. Strange because I have an earth wire on the case but of course with a 200 amp fuse protecting the inverter it takes a big short to blow the fuses. My system is a 24 volt system
Anyway after waiting in these new slow delivery times for parts I replaced the mosfet and driver boards and it is alive again.
Just thought that I would warn anyone with a Powerjack not to mount it on its side.
Hope everyone is well out there
Pete

Offline dochubert

  • Full Member
  • ***
  • Posts: 247
  • Karma: +3/-0
  • 11 powerjacks, 9 that run, 3 actually used daily
Re: PowerJack smoked
« Reply #1 on: March 20, 2021, 06:19:21 pm »
Hi Pete,
Sorry to hear your pj blew up.  As to mounting on the side, I remember someone on this forum hanging the transformer on a leather strap through the center hole.  Got good airflow that way and didn't have any metal close to the windings.
(Might be easier to just lay it flat.)
Glad its back up and running.
We're all going to DIE!  (eventually)

USA = Communist former republic
---  dochubert --

Offline Pete

  • Sr. Member
  • ****
  • Posts: 357
  • Karma: +19/-1
  • Mount Barrow Tasmania
Re: PowerJack smoked
« Reply #2 on: March 21, 2021, 07:22:45 pm »
Thanks Doc, yep I just laid it flat this time. Been running well now for a few days. One day I will get around to trying to fix the old boards, I have new mosfets and surface mount transistors, but playing with surface mount stuff is not fun. May be ok if you are 20 years old with perfect eyesight but even then I don't think I would like it.
Cheers
Pete

Offline lighthunter

  • Sr. Member
  • ****
  • Posts: 289
  • Karma: +11/-0
Re: PowerJack smoked
« Reply #3 on: March 23, 2021, 07:23:03 pm »
quote "The Transformer has been affected by gravity and with the windings touching the case it has worn through some varnish on the windings and shorted to the case. "

Wow, thats too bad. I was thinking the transformers
had a rubber pad on top and bottom with square plate over
each end with bolt securing them tight. My memory is bad tho and i never had an 8k only 6k's. The way mine has been assembled for years now is two of the original transformers stacked and another secondary wound around the whole thing then the stack is rotated 90 deg so the fan blows through the hole. The covers are squeezing the transformers tight to hold in place ( the covers have an inch gap because of thickness) more air venting Ha! I dont recall what i put between aluminum and the windings. Im thinkin i put rubber but i better check. Thanks Pete!

Good to see you moved up to LFP Dochubert! I have only 200AH lfp @ 48v and still using the 540AH 48v traction. It had decreased in capacity to about 180AH with high self discharge and low voltage, in fact would boil violently at 56v. I put in 3oz/cell battery equaliser 6 months ago and now capacity is 275AH and i saw it floating at 55v and 2.75amps a couple days ago. I realize additives are very controversial. This one responded well but you always have to consider you couldve spent the $150 towards new batteries too.

LH
Health Warning: May contain traces of nut!
LH

Offline dochubert

  • Full Member
  • ***
  • Posts: 247
  • Karma: +3/-0
  • 11 powerjacks, 9 that run, 3 actually used daily
Re: PowerJack smoked
« Reply #4 on: March 24, 2021, 06:53:10 pm »
Quote
Good to see you moved up to LFP Dochubert!

Great to hear from you LH!  Been too long!
Yes I made the switch when my sla batteries started failing at 3 years of use.  Very happy so far and about to double the size of my main 48v lifepo4 bank.
So you used the chemical additive on your forklift battery? I've always wondered if that really worked.
Looking forward to some new posts about what you've been doing!
We're all going to DIE!  (eventually)

USA = Communist former republic
---  dochubert --

Offline Pete

  • Sr. Member
  • ****
  • Posts: 357
  • Karma: +19/-1
  • Mount Barrow Tasmania
Re: PowerJack smoked
« Reply #5 on: June 23, 2021, 01:58:05 am »
Well the powerjack blew up again. This time I was using my table saw, it was running well, then I went to restart it and it tried to start then just ran down.
The little Taiwanese lady in the inverter was telling me there were multiple faults and the inverter was beeping constantly.
Even after I turned the inverter off there was a constant alarm sound.
So I disconnected it to stop the sound.
I pulled it apart and found that it had blown the AC mosfets to bits, so I changed the boards for some spares I had on hand.
I changed the driver board with a spare too.
Then when I turned the inverter around I found that the DC mosfets were also blown.
So I changed them too.
A quick test shows that it is working again, but as it is the second time that an inductive load has killed it I am a bit wary.
I think it is time to get hold of an 8010 board for it too. I really only want an inverter not all the other stuff such as a charger etc.
So I will install it tomorrow and see how it goes, hope it lasts until a more simple replacement board arrives.
Pete

Offline lighthunter

  • Sr. Member
  • ****
  • Posts: 289
  • Karma: +11/-0
Re: PowerJack smoked
« Reply #6 on: June 23, 2021, 05:24:15 pm »
Hi Pete,
 
I feel your pain. I too have a few failed inverters in my past.

Most of the time if not all of the time, there is a reason when mosfets perish.  Usually the failure happens because of one of two things. 1... Load current exceeds specification in some way.
Load current sometimes just happens as part of life. Short circuit... like in my case, relay contact failure.
Or
2)  Wrong sizing of filter components. Poida did all the legwork of figuring this out. Warpspeed contributed imensely as well, take a look at this thread if you havent already done. Resonant frequency can be a killer of the best bridges (road bridge) tacoma narrows, let alone an inverter mosfet bridge.

https://www.thebackshed.com/forum/ViewTopic_mobile.php?FID=4&TID=9409&PID=122471&LastEntry=#122471

I certainly dont know all the answers and im not suggesting you need to invest much time in it. If there is evidence of an unexplained problem though, it can be worth it to make a change to the choke or cap to see if things improve. From reading threads it appears like some have had transformer/choke sizing that continued to eat mosfets regardless of the inverter boards until changes were made. I do think there is a solution that will make it indestructable for normal use.

Glad u got her running again!
Health Warning: May contain traces of nut!
LH

Offline Pete

  • Sr. Member
  • ****
  • Posts: 357
  • Karma: +19/-1
  • Mount Barrow Tasmania
Re: PowerJack smoked
« Reply #7 on: June 23, 2021, 05:36:57 pm »
Thanks for the reply LH , I will look up the post you mentioned.
I have ordered a 24 volt 5000 watt board to have on hand if it becomes smoke again.
I am thinking it has to do with starting current , but as both saws I was using were universal motors it seems odd that the starting current was high enough to kill it.
I have my 500 Farad capacitors now and will charge them and fit them in the next few days. Hopefully that will help with starting currents and voltage dips.
Cheers
Pete