[VAC] Re: '59 Overlander

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

I don't remember them as being a lot more tolerant of discharging, they
were lower capacity in the same volume because the plates were thicker
and capacity is mostly a function of plate area. The thicker places may
have been a bit more tolerant of deep discharges because they could have
been stronger. But that depends on the alloying of the lead, typically
in those days the lead was alloyed with antimony which had adequate
strength but a great deal of local action that tended to discharge the
batteries fairly rapidly. The modern high output batteries use calcium
metal as the alloy in the lead which solves most of the local action and
self discharge, but the plates aren't nearly as strong and then are made
much thinner to achieve more area and so more capacity.

The normal product of discharge is lead sulfate. Lead sulfate is larger
than the sponge lead it came from and that's what puts stress on the
plates.

In the really olden days, cars were equipped with hand cranks so running
the battery down wasn't as much of a problem, but hand cranks seem to
have gone out with the end of the 30s.

Gerald J.