Did I kill my batteries?

I run a small off-grid system in my seasonal cabin. The system sits unused during the Maine winters. I keep the solar panels and charge controller hooked-up to the batteries during the winter. So far this has worked well for the last 5 years. Usually I snowshow into my cabin a few times during the winter to check things out, but didn't get a chance this year.

I checked the system today and for some reason my charge controller crapped out and was showing a fault code. Anyways, my batteries were at 12.1 volts. These are 5 to 6 year old Trojan T-105's (4). Should I plan on buying new batteries?..or can they be saved? What's the best way to try to save the batteries?



  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Did I kill my batteries?

    First thing you do is recharge them. See if you can get the SG up and equal on all cells. Then see if it stays there.

    You don't know how long they were sitting at <75% SOC so there's no telling how much sulphation may have taken place. The good news is that in cold temperatures the chemical activity slows down, including sulphation.

    Given the Voltage reading (very low) it may be the charge controller was acting as a load too. Otherwise one would expect a higher reading even after sitting for months (if they were fully charged to begin with).

    But you already know you're going to have to buy new batteries sooner rather than later now.
  • mike95490mike95490 Solar Expert Posts: 9,511 ✭✭✭✭✭
    Re: Did I kill my batteries?

    You can direct wire the panels to the batteries, bypassing the dead controller, you just have to use a voltmeter every half hour to keep an eye on the charge voltage.

    I'm assuming 20V panels and 12V batteries.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Did I kill my batteries?

    go ahead and check the water levels and sg and give them a good charging if none of them developed any cracked cases from the electrolyte freezing up due to lower sg during the winter. odds are i feel you are ok though.
  • MaineCabinMaineCabin Solar Expert Posts: 29
    Re: Did I kill my batteries?

    Thank you all for the responses. I'm going in today with my generator and give them a good charge...we'll see.
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