In message , Marland
writes

And unless you have a source of free distilled water then the money
purchasing that may be be better put to buying a new battery which for a
moggy wont be too onerous at £50-£60 unlike the couple of hundred that
modern tailored batteries seem to be.

I tend to agree. Top of my head I would have said the current battery
is about three years old, but in reality, probably at least twice that.
Modern sealed battery and yes, around 50 pounds to replace.
--
Graeme