🚀 go-pugleaf

In article <BzD4pI.JE5@gabriel.keele.ac.uk> you write:
>From article <Bz7tFD.CF6@ais.org>, by draper@ais.org (Patrick Draper):
>
>> In cold weather chemical processes generally proceed at a slower rate. A
>> marginal battery in warm weather might not crank out enough juice to turn an
>> engine over in cold weather.
>
>But wouldn't it warm up as soon as the starter tried to draw current (a
>couple of hundred amps I believe) from it?  Does cold affect its stored
>energy, or just the internal impedance?  Does the EMF depend on temperature?

I might be able to comment a bit, having spent some time dealing with
survival of batteries under thermal cycling.  The main effect is to
raise the internal impedance a lot, and the EMF slightly.  The amount
of current going out is not enough to significantly raise the
electrolyte temperature before the the boundary layer acts like a
voltage divider and really bites into the current available.  (For the
same reason, the voltage drops very rapidly.)  But the main effect is
the internal impedance, which is an Arrhenius temperature dependance,
if I'm not mistaken.
Steve Axdal   Computing Device International, Inc.
app@shamash.cdc.com