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'Frosting' on top of Ni-Cd batteries

Discussion in 'Power Electronics' started by gubavac111, May 26, 2019.

  1. gubavac111

    gubavac111

    11
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    May 18, 2019
    Just wondering what this "frosting" on the Ni-Cd battery cap could be? How is it created? Is it dangerous? Should it be removed?

    Check the pic below.
     

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  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,034
    1,810
    Nov 17, 2011
    Looks like these batteries are leaking. You can remove the white stuff, but the batteries are degrading over time.
    Are you sure these are NiCd batteries? From the look of it I'd say these are lead acid batteries.
     
    gubavac111 likes this.
  3. duke37

    duke37

    5,189
    704
    Jan 9, 2011
    Ni-Fe batteries will produce sodium carbonate fuzz.
     
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  4. gubavac111

    gubavac111

    11
    2
    May 18, 2019
    Definitely Ni-Cd batteries, installed in August 2018, still have a battery brochure.
     
  5. WHONOES

    WHONOES

    635
    122
    May 20, 2017
    Looks like the cells have valves on them to vent gases to atmosphere when they are overcharged or abused in some way. The frost is precipitated from the gas released and represents a loss of electrolyte which means reduced capacity.
     
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  6. Bluejets

    Bluejets

    3,365
    673
    Oct 5, 2014
    Bit like the formation of corrosion on the positive of a wet lead acid cell.

    Similar Ni-Cd were used in a pump station we used to maintain back in the 80-90's.

    The difference was the interconnects were "plated" and kept clean to start with.
    Then a smear of vaseline kept any terminal/connector corrosion caused by a combination of any escaping gases and use of differential materials (terminal to connector) at bay.

    AS with lead acid, usually only the positive.

    More info on wet ni-cd cells here.

    https://batteryuniversity.com/learn/article/charging_nickel_based_batteries
     
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  7. Warren

    Warren

    6
    2
    Dec 6, 2016
    The electrolyte in Ni-Cd batteries is Potassium Hydroxide (KOH) solution. Slight leakage, especially when overcharged, occurs through "venting", after which evaporation of the water from the solution leaves a residue of the KOH. This "frosting" is quite caustic and should be removed with a mildly acidic solution, like vinegar. Avoid contact with the skin, and particularly, the eyes. As other commenters have noted, the deposits indicate loss of electrolyte and a corresponding reduction of the AH capacity of the cell.
     
    gubavac111 likes this.
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