PIP-5048GK error code 51

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powerhey

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Feb 28, 2020
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Sent the following to MPP Solar, has anyone else had this problem with the PIP-5048GK? No idea what caused it.

Regarding the PIP-5048GK that I bought last year, the unit is no longer working:
  • It's only been used for perhaps 100 or 200 hours since I bought it (it's just for back up power. Most of those hours were for testing the battery).
  • It's unable to supply AC from the battery - it comes up with error 51.
  • I tried disconnecting the battery and restarting the unit several times but no luck.
  • Supplies AC when powered from mains, but when battery is connected it stops powering and reports error 51.
  • Solar input has never been used.
  • Batteries are fine, well connected.
  • I did connect the batteries perhaps 100 times in total without using a resistor first, suddenly charging the caps up with a slight pop in the DC breaker. Wouldn't have thought that would matter too much though.
  • It's been left unplugged from the wall, so I don't see how a surge in the mains could get to it. Other small plugpacks are close by and are fine.
  • The only AC load is ~1 watt for red lights inside power boards.
  • I noticed it briefly showed the battery voltage at ~38V, even though my own battery meter didn't budge. Then, it showed 53.1V.
  • My own battery volt meter never showed and sudden dip; only what you'd expect from the unit pulling its overhead load.
  • Battery is 48v 150ah lifepo4.
  • I used it a month or three ago no problem. I've got no idea what's happened/failed between then and now.

  • Ever since I first used it, sometimes when starting up, it will begin its countdown, get down to 2 and then suddenly die (screen goes blank and dark). I would restart it (using its on/off push switch and reconnecting the battery if it didn't respond) and it would usually work. Sometimes it would die again and I would reset it again, until it worked. The whole thing would take less than a minute to get running. Once it was running it never played up so I didn't worry about it. I'm not sure if this offers any diagnostic clues.
 
By the fault code, the over current sensor is triggered. Did you check for a short on the DC battery terminal and PV input?
 
There are no shorts.
I took the board out this arvo (it's no longer under warranty) and the mosfets are fine, caps are nice and flat on top, and PTC's and NTC's look fine.
Spent half an hour looking for solder dag shorts; none found.
Built in 150A fuse is fine (otherwise it'd be completely dead I guess).
Wish the error code gave more detail besides 'current surge'.
 
Could be a faulty current shunt. but other than replacing the board not sure what else you can do to troubleshoot
 
Yeh, would be a shame to replace the board, and would be a greater shame to have it happen again!
 
I got some test instructions from MPP Solar (using $50 multimeter with diode test works fine) and everything was as it should be, so there's still no diagnosis clues. Waiting to hear back from MPP Solar for the next diagnostic step.

A few months I did put a resistor across the battery DC breaker to keep the inverter's caps charged up (forget if it was like 10k or 40k, but I do remember that it settled at leaving ~8v across the breaker, meaning the caps charged up to ~45v (53.2-8) I don't see how this would upset the inverter though. Before I disassembled the inverter, i disconnected this resistor, opened the breaker, turned the inverter on (to drains its caps), turned the inverter off, closed the breaker (Noark 63A breaker gave a modest "pop"), turned on the inverter, but still got error 51.
 
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