Monthly PM for off grid

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Thom
Thom Solar Expert Posts: 196 ✭✭✭
in Solar Beginners Corner #1
Every month I fill and EQ batteries . Should I be doing more on a monthly PM ?
Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator . Added 2@ 100w panel with a midnight brat 
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #2
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    Re: Monthly PM for off grid

    If you find you need to fill your batteries every month you may be over watering them.

    Unless you regularly draw your batteries down below 80% of capacity, or have your equalizing set too high or too long I find I need to water my batteries every 2-4 months. So people think they need to fill to the bottom of the plastic, when it's actually 1/8th to 1/4 below the plastic to allow for expansion when the battery is warmed and bubbling. normally a small area of dampness or water marks around the battery cap is normal from misting, but a lot of wetness on the top of the battery can also indicate this.

    Also old batteries can require more often filling.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,445 admin
    #3
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    Re: Monthly PM for off grid

    If you have a 12 volt series/parallel battery setup (2 strings of 2x 6 volt batteries)--Then I would get a DC Current Clamp meter and check the heavy charging/discharging current between strings (look for good current sharing) and double check battery/cell voltages (and investigate differences in battery voltages--4 batteries, if there are any that are high or low voltage vs the rest).

    Also check specific gravity of cells--look for spread of readings (greater than ~0.015 to 0.030 would suggest equalization charge).

    Looking for wiring and open or shorted cell problems before they get out of hand and damage the other batteries.

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