On Fri, 9 Oct 2009 15:57:07 +0100, D.M. Procida wrote:

It's a fairly new battery, yet either there is something wrong with it,
or there is something wrong with the car (that is draining it rapidly
while it sits on the driveway).

The other day it was flat, so I charged it for an hour or so, it started
up right away, then later that morning it was flat again.

Oh dear that doesn't bode well. One thing that car batteries hate is
having a deep discharge. A fairly new one should survive but one a
year or three old may not.

You need to find out if the car has a fault that is taking more than
a few 10's of mA when just parked up. You may need to measure this up
to half an hour after switching off and locking the car to allow it
to fully "go to sleep".

--
Cheers
Dave.