Just had a "fail to start" on the 4/4.
Failure to turn the engine above a snails pace. Checked battery and it was ok. Then systematically cleaned and reseated earths at battery and engine/chassis. That did the trick - fired up straight away.
My experience with batteries has been pretty good. Had one post come loose 20+ years ago. Battery on Focus failed after 10 years.
Apart from that keeping them clean/topped with distilled or deionised/works ok.
When I was a metallurgist in a steel plant we had access to a Lab so could make battery acid easily. BUT!!!! BE CAREFUL!!! Sulphuric acid is nasty stuff - ALWAYS add it to water NOT water to it! When mixed it gives off a hell of a lot of heat (its VERY exothermic) and we used to mix it in Pyrex flasks and it boiled in them if we added it too quickly.
Sulphuric was also used to clean steel parts up too - a mate had an old AA badge replated after prepping it himself using sulphuric. We used to clean up samples of steel in it to remove all scale and reveal clean metal for inspection for surface cracks etc. Those were the days! Acces to machinist to make things and furnaces to heat treat them.
We also got up to some errrr fun things too - but thats top secret!
