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To EQ or not to EQ?

Discussion in 'Musings With Maine Sail' started by gettinthere, Jul 11, 2018. Add this thread to a FAQ

  1. gettinthere

    gettinthere

    Joined Nov 26, 2008
    1,800 posts, 130 likes
    Endeavour 42
    US Cruisin
    It's been about 6 months since I've been on shore power. Charging systems have kept the house bank above 90% SOC frequently, 80% SOC most of the time and never below 65%. I finally am at the dock with shorepower and the charger has brought me up to 100%. My info says to equalize until SG is full, which for my Trojans is 1275. I am already at 1275 SG before equalizing so how long should I EQ??

    THANX!!
     


  2. Charles Erwin

    Charles Erwin

    Joined Jan 30, 2012
    919 posts, 81 likes
    Nor'Sea 27 - "Kiwanda"
    US Portland/Anacortes


  3. gettinthere

    gettinthere

    Joined Nov 26, 2008
    1,800 posts, 130 likes
    Endeavour 42
    US Cruisin
    "Stop at two hours, let battery rest, check specific gravity." ... which is the center of my question. SG for my batteries is 1275 and they are already there without EQ
     


  4. Maine Sail

    Maine Sail Moderator

    Joined Feb 6, 1998
    10,656 posts, 489 likes
    Canadian Sailcraft 36T
    US Casco Bay, ME
    EQ does a few things:

    #1 It serves to re-balance the individual series cells by applying a controlled over charge , a 12V battery has six 2V cells in series, EQing helps to brings the low cells up to 100% SOC. If all cells are already in balance then the EQ is not really needed for "balance" purposes. If you're routinely charging at 14.7V to 14.8V I've found the need to EQ, for "balance" issues, diminishes quite a bit. However if you were charging at only 14.2V to 14.4V (old school FLA charging mentality) series cell balance issues will be more prevalent.

    #2 It can help to shed some of the dead and clustered lead sulfate from the surfaces of the cells thus allowing more usable cell surface area to be usable.

    #3 It can help to reconvert savable lead sulfate back into active material (Savable = lead sulfate in the Emergency Room on life support). Capacity loss, from dead non-reconverted lead sulfate can become permanent in less than 30 days. EQing once every 20-25 days +/-, for at least 30 minutes or so, for a 24/7 PSOC use cruiser, is the best course of action beyond a higher absorption voltage. Higher absorption voltages held long enough do help reduce the need for EQing..

    #4 Stirs up the electrolyte and helps minimize the effects of electrolyte stratification. This is not usually a big issue on boats using a 14.7V to 14.8V absorption but is a bigger issue in off-grid / stationary use.
     


    Will Gilmore likes this.
  5. gettinthere

    gettinthere

    Joined Nov 26, 2008
    1,800 posts, 130 likes
    Endeavour 42
    US Cruisin
    So, I did about 2 hours of EQ while I was at the dock. I think you know that my solar controllers are set for 14.7v and I was getting that pretty regularly until one of my controllers started becoming intermittent.
     


  6. Maine Sail

    Maine Sail Moderator

    Joined Feb 6, 1998
    10,656 posts, 489 likes
    Canadian Sailcraft 36T
    US Casco Bay, ME
    How often are you EQing? Are the batteries showing any signs of decline eg: lower morning voltages using the same/similar overnight loads?
     


  7. gettinthere

    gettinthere

    Joined Nov 26, 2008
    1,800 posts, 130 likes
    Endeavour 42
    US Cruisin
    First EQ in 6 months, haven't been to a dock. Recently had lower voltages because of the loss of half of my solar. The controller is working now. I will send it to Blue Sky next month when I stay at the dock during 'cane season.
     



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