On Mon, 29 Dec 2008 20:38:07 -0000, "ForeverArsenal"
wrote in
:

"ForeverArsenal" wrote in message
net...
Hi.
Could anyone advise please

1 led drawing 10mA off a 12volt car battery,how long would
take to use up 1amp of the battery.

Am I right in saying it would take 100hrs,could someone confirm please.

Amp is current, not battery capacity. That's amp hours (current over
time).

Wikipedia:

The battery capacity that battery manufacturers print on a battery is
the product of 20 hours multiplied by the maximum constant current
that a new battery can supply for 20 hours at 68 F° (20 C°), down to
a predetermined terminal voltage per cell. A battery rated at 100 A·h
will deliver 5 A over a 20 hour period at room temperature.

Your LED is drawing 1/100 amp, so it would draw the same power in 100
hours as a 1 amp load would draw in one hour, or 1 amp hours of
capacity.

--
Very best wishes for the holiday season and for the coming new year,
John