Dead FLA bank - trying to bring back from the dead

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  • Riley5781
    Member
    • Dec 2015
    • 98
    #1

    Dead FLA bank - trying to bring back from the dead

    Well after 6 years of very careful battery management, I did the unthinkable.

    My solar system is for a season spring/summer home. For over-winter, my usual process is to 'mothball' the batteries (bring to full charge with generator then shut down system and open breaker to the battery bank so it's totally open circuit). This has served me well for 5 or 6 years.

    Well back in October (3 months ago), when I was opening the breakers and the MPPT charge controller went into fault due to no batteries (due to the sun being out). That freaked me out so I reclosed that breaker and continued to pack-up and head home. Figured I would read up on this later and then correct the issue.
    See this thread if interested: https://www.solarpaneltalk.com/forum...out-of-service

    Well I should left the breaker open because now the battery bank is fully discharged when I returned yesterday.
    BTW - my solution to the charge controller fault is to place into 'STANDBY' state then open the breaker.

    Anyway, I am recharging the battery bank with my generator (after boot-strapping the inverter/charger). I stopped over night to let it cool and me to sleep. The batteries had no load overnight.
    This morning I restarted the charging process and now at Absorb. I will be checking the SG and check the relative battery voltages (48volt bank with 8x6V batteries).

    Besides checking for SG, looking for bad cells and adding water (and an EQ cycle or 2), any other advice?

    My assumption and fear is that the batteries are toast but maybe I can salvage them for another year or 2?
    Last edited by Riley5781; 01-20-2022, 12:29 PM. Reason: Fixed spelling errors and minor clarifications
    Tags: None
    • SunEagle
      Super Moderator
      • Oct 2012
      • 15125
      #2
      Your assumption and fears are real. The batteries are toast. Time to let them go and get a new set or you can spend a lot of money and get a very small amount of power out of them.

        Comment

        • Riley5781
          Member
          • Dec 2015
          • 98
          #3
          Originally posted by SunEagle
          Your assumption and fears are real. The batteries are toast. Time to let them go and get a new set or you can spend a lot of money and get a very small amount of power out of them.
          Thanks for the response.
          After spending Day 2 trying to charge them, I can see they are toast.
          Taking a lot of charge (got through Bulk but now stuck at high Absorb) and seem to be converting that into heat and bubbles....

          Time to figure out next set...
          I guess 6/7 years isn't bad for my first set.... If I had mothballed like every other year, I would be OK, ugh...

            Comment

            • SunEagle
              Super Moderator
              • Oct 2012
              • 15125
              #4
              Originally posted by Riley5781

              Thanks for the response.
              After spending Day 2 trying to charge them, I can see they are toast.
              Taking a lot of charge (got through Bulk but now stuck at high Absorb) and seem to be converting that into heat and bubbles....

              Time to figure out next set...
              I guess 6/7 years isn't bad for my first set.... If I had mothballed like every other year, I would be OK, ugh...
              Well FLA type batteries will slowly die even if they are just kept on a float charge. They can die sooner if they are discharged too much and have a built in cycle count based on how far they are discharged or what temperature they are kept in.

              So depending on how much you used them 6/7 years are actually pretty average for FLA.

                Comment

                • Riley5781
                  Member
                  • Dec 2015
                  • 98
                  #5
                  Originally posted by SunEagle

                  Well FLA type batteries will slowly die even if they are just kept on a float charge. They can die sooner if they are discharged too much and have a built in cycle count based on how far they are discharged or what temperature they are kept in.

                  So depending on how much you used them 6/7 years are actually pretty average for FLA.
                  True but I have babied these batteries. They were still going strong until I flattened them over the last 2 months by having the MPPT controller connected with snow on the panels.
                  They were probably wearing a bit and had lost some of their capacity but still seemed fine for my application.
                  I have given up on them.

                  It is interesting to think about where is all that charging energy going. That was a lot of Watt/hours I pushed into them... I guess just heat?

                    Comment

                    • SunEagle
                      Super Moderator
                      • Oct 2012
                      • 15125
                      #6
                      Originally posted by Riley5781

                      True but I have babied these batteries. They were still going strong until I flattened them over the last 2 months by having the MPPT controller connected with snow on the panels.
                      They were probably wearing a bit and had lost some of their capacity but still seemed fine for my application.
                      I have given up on them.

                      It is interesting to think about where is all that charging energy going. That was a lot of Watt/hours I pushed into them... I guess just heat?
                      I agree that some batteries last much longer then expected. I have a set of 4 12v AGM 50Ah type that lasted over 7 years but I did not realize that wiring them in parallel could hurt them. I rarely used them but they have finally gave up their life and no longer hold a charge. I plan on replacing them with 2 6v deep cycle type. Hopefully they will last as long as the other ones but I know it will be less expensive then the 4 AGM and actually have more Ah rating

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