I have done the same and batteries became usable again.
I have also flushed out batteries with distilled water and refilled them with sulphuric acid...
Hey OrganicFoxes, be sure to have your alternator & voltage regulator checked. It sounds like your battery electrolyte boiled away, which is usually...
My late Dad, rest his soul, only knew how to connect with women that should never be in a driver seat. My mother was famous for driving the car with...