[sdiy] Poly 61 near death?

[Mike I.]

Hey - isn't the electrolyte in a NiCd battery mainly potassium hydroxide?
This is extremely alkaline and corrosive... and apart from a thorough
washing would need to be neutralized with an acid. Lead-acid batteries do
use sulphuric acid for the electrolyte... and ordinary zinc-carbon
non-rechargeables use ammonium chloride which produces an acidic solution...
and alkaline non-rechargeables  are indeed alkaline - again with potassium
hydroxide in the electrolyte. So neutralize acid with alkaline, and vice
versa. A weak acid like vinegar as suggested should be fine, and a weakly
alkaline solution like sodium bicarbonate or possibly ammonium hydroxide for
acids.
Cheers, Mike