On Tue, 06 Sep 2005 19:46:33 +0100, Huge wrote:

I didn't see the original posting, but IME deep discharging a car
battery, by allowing a current drain of 200mA for a couple of weeks,
for example, kills them stone dead.

Lead-acids of the automotive type really dislike being taken below 80% of
capacity. Taking them to 20% of full charge on a regular basis reduces the
lifetime in cycles by a factor of about 10. There are lead acids designed
for taking this treatment, leisure type and traction duty (think milk
floats) which will go into deep discharge without damage. The problem is
they are not designed for suddenly dumping a couple of hundred amps at the
drop of a hat.

John Schmitt

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