Batteries self-discharging on concrete- - - - - -that's as out of date as "keep it running while adding water to the radiator". The radiator advice went obsolete in 1928 when they put a water pump on the Model A, and the switch from wood case batteries to hard rubber in the mid-1930's stopped the self-discharge problems on concrete. Today's plastic battery cases have such a high dielectric rating the battery could sit half-submerged in water and not self-discharge. BTW, discharged batteries freeze. A fully-charged battery will go to many degrees sub-zero with no freezing concerns. If a battery is stored in cold conditions, it does need to be trickle-charged occasionally, but that's also true in hot conditions.
Jerry
