Does anyone know what the black smudgy deposit is that forms on the underside of wet cell lead acid automotive batteries is?
It looks a little like soot and is easily wiped away.
I've heard it can suggest the battery is failing. Is there any substance to this or is it just an anecdotal red herring?
Cheers D.
The technical term is "Krud" :-) Might be worn off the casing ??
Oxide is bad
It could be lead oxide - googling had found nothing but I just looked at lead oxides and found this:
"The so-called black lead oxide, which is a mixture of PbO and fine-powdered metal Pb and used in the production of lead acid batteries."
We've got a few vehicles and most of them seem to have it to some degree - even on a couple of batteries that are only 6 months old.
I nearly used the common trade term of "black s*it", "krud" is more professional.
It could be from the casing but I wouldn't think so as it's to be deposited on the bottoms of the vent plugs as if carried there by the electrolyte "bubbles" during charging.
a by product of the charging , when enough "black s**te" accuumuates the battery is buggered
No. It is from a failed or failing cell.
Pretty much, you are "really full of it".
Ahhh ! THAT Krud !
Didn't come up in the original post :-)
Defo lead oxide...
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