Quote:
Originally Posted by Phil Waterman
I suspect that it would have started on the 6V if the battery had been warmed
|
No doubt about it Phil, and as you discovered there's no advantage in using a 12V battery if it's equally cold. This is explained by physics - low temp does not effect battery voltage, which is purely a function of the anode/cathode material (lead/lead oxide, nickel/cadmium, copper/zinc, etc). It does however reduce current available, by slowing the rate of chemical reaction at the plates. Hence at very low temps, even a fully charged 12V battery will deliver no more cranking current than a 6V battery (assuming they're the same size). This effect can be noticed after charging a car battery overnight on a concrete floor, even in our mild Australian winter.
The solution of course is to warm the battery as you say, and it's interesting to see it only took an hour on the charger in your case. Of course, this may not always be convenient - many times on cold mornings I've had to pour boiling water over sick batteries to get to work on time!
Anyway great photo and story Phil, I take my hat off to you guys who put up with sub-zero climates. Personally I would have chucked in the towel when the uni-joint blew and retired to the house to hibernate until Spring. Hell I even hibernate in winter here!