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Positive Battery terminal turns Black???

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  • Positive Battery terminal turns Black???

    Hello to the list,
    I have had a lot of batteries in my life and never seen this. I pulled my Trojan deep cycle the other day to do a maintenance charge and the positive battery terminal was blackened. I wired brushed it off and the next day it was black again just sitting (not on the charger). I've had this battery for a number of years and I'll have it checked but has anyone seen this before? Is it on it's way out?
    Thank, Steve
    WizardIII

  • #2
    Re: Positive Battery terminal turns Black???

    The black stuff is lead oxide, produced when a battery releases hydrogen gas during charge/discharge cycles. Your battery probably has enough of it built up on the outside of your battery to create a small electrical current path to ground. Clean the battery off with baking soda or the like and see if it stops. If it gets real bad your battery may need replacing.
    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
    07 Seadoo GTX
    Merc Adults Only VP Adults Only
    G-Dad always said "First Liar doesn't stand a chance"

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    • #3
      Re: Positive Battery terminal turns Black???

      Originally posted by AllDodge View Post
      The black stuff is lead oxide...
      I am not a chemist, but I suspect the black material on the battery terminal might be lead dioxide, and it would be created by having lead in contact with sulfuric acid, not from hydrogen gas.

      Lead oxide would be red or yellow in color.

      Cf.: Lead dioxide - Wikipedia, the free encyclopedia

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      • #4
        Re: Positive Battery terminal turns Black???

        Originally posted by jhebert View Post
        I am not a chemist, but I suspect the black material on the battery terminal might be lead dioxide, and it would be created by having lead in contact with sulfuric acid, not from hydrogen gas.

        Lead oxide would be red or yellow in color.

        Cf.: Lead dioxide - Wikipedia, the free encyclopedia
        I'm not a chemist either, but your link shows it's dark brown.

        Lead oxide - Wikipedia, the free encyclopedia Third line down under "Less common lead oxides are:"

        Either way it's some kind of oxide which is black and my research came up with what I found. If it's something else let the chemist in the forum please advise
        94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
        95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
        07 Seadoo GTX
        Merc Adults Only VP Adults Only
        G-Dad always said "First Liar doesn't stand a chance"

        Comment


        • #5
          Re: Positive Battery terminal turns Black???

          Originally posted by AllDodge View Post
          I'm not a chemist either, but your link shows it's dark brown.

          Lead oxide - Wikipedia, the free encyclopedia Third line down under "Less common lead oxides are:"

          Either way it's some kind of oxide which is black and my research came up with what I found. If it's something else let the chemist in the forum please advise
          Ayuh,.... I ain't either, so I'd just call it Corrosion,....

          Clean it to Shiny metal clean, 'n grease it to keep it that way,....

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          • #6
            Re: Positive Battery terminal turns Black???

            Originally posted by AllDodge View Post
            I'm not a chemist either, but your link shows it's dark brown.

            Lead oxide - Wikipedia, the free encyclopedia Third line down under "Less common lead oxides are:"

            Either way it's some kind of oxide which is black and my research came up with what I found. If it's something else let the chemist in the forum please advise
            I think you must be referring to this section of the article you have cited:

            "...so-called black lead oxide, which is a mixture of PbO and fine-powdered metal Pb..."

            How would you get fine-powered lead on the battery terminal?

            And what is the reaction with lead and hydrogen gas that produces an oxide of lead?

            If you have sulfuric acid (H2SO4) and lead (Pb), it is not too hard to see how you might produce PbO2 from a reaction.

            Yes, I think it is better to call the black stuff as black stuff, rather than infer some chemistry about its nature.

            The curious thing: there is a phenomenon known as "black wire corrosion" which seems to affect the negative circuit of a battery powered system, rather than the positive. But this seems to be most common with NiCad batteries, not lead-acid batteries.

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            • #7
              Re: Positive Battery terminal turns Black???

              Regardless of what the chemical reaction is, it should not be happening.
              It indicates that the battery is leaking and seeping acid onto the top and posts.

              Dissolve a spoonful of baking soda in a glass of water.
              Dribble a small amount on the battery posts; If if fizzes, you have acid on the post.
              The battery has seen its better days.
              Bill, Lorain Ohio

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              • #8
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                Re: Positive Battery terminal turns Black???

                Well, thanks for all the input. Prior to my post I did put some baking soda solution on the terminals looking for a possible crack. A small amount of sizzle.... that was expected. There was some liquid on the sides (possibly topped off too much before so I took the advice of ALLDodge and cleaned the entire battery case. It's been a couple of days now and the terminal has stayed clean. The battery may indeed be going south but at least it doesn't have a cracked case.
                Thanks again to all,
                WizardIII

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