Black stuff in battery liquid

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lazza
lazza Solar Expert Posts: 336 ✭✭✭
HI

I've noticed in a few failed batteries, that they have a common characteristic. They have a kind of black oily substance below the vent caps and in the electrolyte.

Does anyone know what this chemical is, and why it may occur??

thanks
Larry

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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
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    Re: Black stuff in battery liquid

    Oil? Is this an old battery from else where? they make and oiul additive that is supose to prevent excessive out gassing.

    Thermoil is one brand.
    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.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,476 admin
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    Re: Black stuff in battery liquid

    I am not sure--but I have seen similar that I always assumed was some sort of Lead Oxide in a powdery form that floated on the surface (sort of like graphite) and was not really oily.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lazza
    lazza Solar Expert Posts: 336 ✭✭✭
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    Re: Black stuff in battery liquid

    Yeah, more powdery than oily..... any idea what might cause it?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,476 admin
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    Re: Black stuff in battery liquid

    Over equalization can create/drive oxygen into the positive grid and plates.

    Running electrolyte below the top of the plates can expose them to more oxygen.

    My guesses.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
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    Re: Black stuff in battery liquid

    Just watered my batteries today and I noticed both things - the black under the caps and the "oily" look on the top of the water.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Black stuff in battery liquid

    It was ever thus,,

    I have always had black residue on the caps, and oily look to the electrolyte. I clean the caps of the gook when I water. I always assume it was lead oxide.

    Tony