This is a shot of the shed with the battery sitting on the green box. The temps in here mimic that of a boat on the hard, in the North East, quite well.
"But RC won't my battery self discharge if left off a charger all winter?"
In cold weather the self discharge rate of lead acid batteries slows dramatically to the point of nearly stopping. The colder the temps the slower the self discharge. In an area that has more temperate winters, the rate of self discharge will be slight faster.