XW6048 with 2 MPPT60-150 charge controllers - one controller now gets F71 Battery Over Current

pcguy2u
pcguy2u Solar Expert Posts: 151 ✭✭✭
All of a sudden after years of pretty normal operation, I get fault F71 on MPPT60 00, the circuit breaker trips and the 00 controller screen goes blank.  Flipping the breaker immediately brings it back to life and it happens again in a few days.  The other breaker, presumably for MPPT60 01, never trips during the time the 00 controller is off, or anytime.

I assume that this is a wiring issue and have checked/tightened all the lugs just a few moments ago (and read the related thread), so not sure if that has had any effect.  Also, the fault message says MPPT60 00 but as I think about it, this is after the event and I'm not sure if the 00 controller is actually the problem or not since the system views the controller as 00 when there is only 1; base zero and all.

Have also checked the voltages in and out of all the connection and there are no glaring differences.  Everything looks pristine, just like new...

Checked the lugs under the controller access cover and snugged them up a bit. Too soon to tell.

One thing that bothers me about the system is that from day one, MPPT60 00 has consistently read lower on the SCP than the 01  controller.  For example, right now at al most 11AM the 00 controller reads about 30A and the 01 reads about 41A and the watts readings vary likewise (00 gets a bit more sun early and 01 gets more late). The input voltages are also the same and read 107VDC+- with a DVM, but the SCP meters do not seem to coincide.  Just now read the SCP and 00 read 19A @ 106, while 01 read 23A @ 101.   Not sure if there  correlation to the problem here, but this is a bit

A couple of pics; the breaker that trips is always the one on the very left:


Any thoughts?

Many thanks, Nick







Comments

  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    edited April 2023 #2
    Here's an update to the PV input numbers (SCP meter readings) provided above from just before 11AM.
    00 19 106
    01 23 101

    And now at 11:45AM
    00 22 106
    01 25 102
    But the input voltages on the back side of the breakers both read the same and were both 107+- much earlier this morning ???


  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    edited April 2023 #3
    And I just checked the temperatures on the controllers and the wiring in the distribution box.  In particular, the battery connections going into the circuit breakers are different, even though they are both less than a foot long and are lugged on to the same bus.  00 was 86f and 01 was 76f on the input (upper) side.  On the output side (lower) they were the same.

    The controllers were not the same; at a point just above the case where the cooling fins start at the center of the box:  00 was 116f and 01 was 111f.

    Ambient was/is 51f and most everything else was not too far above ambient.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Probably a breaker is marginal. Swap the breakers to test this.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    Thanks Dave, thought about that but planned to see if it's less time consuming and cost effective to just buy a new one?  Need to find a source for the proper breaker first... 
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    The store here has them and it is a good thing to buy from them, in many ways. I use them alot of the time for certain clients.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    edited April 2023 #7
    Overnight, while it was dark, started by removing/testing the two one foot cables from the positive battery buss to the breakers in question.  Both tested normally, even under twisting/torqued conditions.  So I reinstalled them and put them on the opposite breaker.  The issue of the two arrays/charge controllers producing significantly different outputs is now much less obvious and as the day progresses, the difference changes with the position of the sun, as it should.  Now at the end of the day, the controller getting the more direct sunlight produces the greater output.  I'm not totally sure, but it also seems that the "sell to grid" event occurs earlier???  The event log does not go back far enough to make a comparison... :0(

    Also, the temp differences on the breaker/cable lugs have now largely disappeared.

    More to follow,  Nick
  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    While this has not happened again, it is nonetheless troubling.  Primarily because of the differences between the input (charging voltage) on the lower side of the two breakers on the left, and the output side.  Also, the temp difference between the two cable connectors on the top of those same two breakers is confounding.  As reported above I removed the two and tested them but not under load; I should have use a battery load tester with each of the short connectors in series and I may do that.  Now the one with the higher temp reading has moved from the one on the left to the one on the right, although the difference is not glaring as it was previously.

    Dave, what was the basis for your decision to replace the breakers you referred to above?  Do those breakers have an internal resistance originally?

    TIA, Nick
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    It is a simple thing to do ! Basic troubleshooting.  Eliminate a problem source that is easy to do.
     Since I do not know the amp rating of the CB, it just was an easy call for me as you could be overthinking this.
    Could also be a mosfet that is intermittent..
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • twistedtree
    twistedtree Solar Expert Posts: 135 ✭✭✭
    I periodically see the same error, but it clears quickly, and no breaker tripping.  The attached panels can't possibly drive it over current.
  • pcguy2u
    pcguy2u Solar Expert Posts: 151 ✭✭✭
    I have been checking the charge controllers daily to date and have found no evidence of this recurring.
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    I periodically see the same error, but it clears quickly, and no breaker tripping.  The attached panels can't possibly drive it over current.
    Firmware up to date?
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • twistedtree
    twistedtree Solar Expert Posts: 135 ✭✭✭
    I periodically see the same error, but it clears quickly, and no breaker tripping.  The attached panels can't possibly drive it over current.
    Firmware up to date?
    I believe so.   Unless there is something recent, I don’t think there have been any updates in years.   I checked probably a year ago. 
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    You are good then as there has not been much reason to update the old mppt-60.
    Check your wiring !  Check your network wiring! Use the raceways designed for network cables.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • tampasolar
    tampasolar Registered Users Posts: 65 ✭✭
    I got two mppt60s too.  Just got the coldest day of the last few years.  So one of the mppt60 units has a fault from dc input over voltage.  At the moment it says 145.2 volts.  I can open all pv breakers, disconnect the dc output, display goes dark.  Then when I power everything up the fault persists.  Even with the gateway/insight, I reset the fault, all the faults, reboot, go into standby, and back to operate.  There is nothing I do that will restore this unit to production.
    Anybody got any ideas ?  It's been running fine for years and years.  We all know the colder the panel gets the more output it has.

    hybrid: xw6848 pro with two mppt60, 6 kw pv
    17 cell 280ah LiFePO4 storage  14 kw
    gridtie: sunny boy sma 2x 5k
    gridtie: fronius ag5100 5k
    Gateway / Insight Local
    xw4548 backup
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    What is the actual voltage on the input with a external voltmeter on a cold morning?  Sounds like your array design did not account for low temps. 
    DC disco on both I/O on mppt for 5 minutes. Measure DC for zero vdc before you connect DC.

    Go Tampa against the Lions today !  I want you guys over Detroit next Sunday. 
     
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • tampasolar
    tampasolar Registered Users Posts: 65 ✭✭
    It appears that playing with the actual buttons on the device, got me a reset.  No reason why the Insight clear was ignored.  It'll take more than one prayer for the Bucs to make it.
    hybrid: xw6848 pro with two mppt60, 6 kw pv
    17 cell 280ah LiFePO4 storage  14 kw
    gridtie: sunny boy sma 2x 5k
    gridtie: fronius ag5100 5k
    Gateway / Insight Local
    xw4548 backup
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Were you trying a clear with Insight Local or Insight Cloud?

    You have a great coach !   I know 3  49er fans that are praying for the Bucs today!  See you next Sunday 🤞



    \





    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • tampasolar
    tampasolar Registered Users Posts: 65 ✭✭
    edited January 21 #19
    Insight Local
    • Version: v1.14
    • Build number: 488
    hybrid: xw6848 pro with two mppt60, 6 kw pv
    17 cell 280ah LiFePO4 storage  14 kw
    gridtie: sunny boy sma 2x 5k
    gridtie: fronius ag5100 5k
    Gateway / Insight Local
    xw4548 backup
  • tampasolar
    tampasolar Registered Users Posts: 65 ✭✭
    edited January 22 #20
    I have three separate JKBMS modules on 3 different banks of Lithium cells.  Do we have to worry about the BMS device pulling and pushing 2 amps between cells when the temps are below 32F ?  I don't think the board senses temperature at all.  I have the 24 cell model with no disconnect, just active balancing.

    hybrid: xw6848 pro with two mppt60, 6 kw pv
    17 cell 280ah LiFePO4 storage  14 kw
    gridtie: sunny boy sma 2x 5k
    gridtie: fronius ag5100 5k
    Gateway / Insight Local
    xw4548 backup
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Check the battery manuals and see what their limitations are...

    I would suspect that any "balancing" current (charging) with sub 32F is damaging to Li Ion cells.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset