In article ,
Tim Lamb wrote:
Newish car battery employed to power pony field electric fence. Likely
to have been left connected well beyond the fully discharged state and
possibly exposed to overnight frost.

Won't take a charge! Yes, I know, throw it away. However, horse person
has gone off with my sound spare. Is *over* discharging an issue?
or...?

Yes. Car lead acid batteries ain't designed for deep discharge. Horse
person should have bought the more expensive types designed for this. But
better still use a load which switches off before taking the battery too
low.

You could try a long charge with a high voltage DC source, like an ancient
unregulated battery charger - or a bench PS set to about 30 volts. But
make sure the bench one has current regulation as if the battery does
recover, it will try to draw lots of current at this voltage.

--
*When did my wild oats turn to prunes and all bran?

Dave Plowman London SW
To e-mail, change noise into sound.