A battery will slowly self-discharge unless the engine is started periodically and run for a few minutes, or some sort of trickle charger is used to maintain it. Discharged batteries can freeze, but it's almost impossible to freeze a fully-charged one. The best possible situation would be to store them in an area that does not go below freezing, and use a trickle charger or a battery maintainer to keep them charged.

Even if it does not freeze, a discharged battery that stays that way for several weeks will develop hard crystals of lead sulfate on the plates, and it will be extremely difficult to recharge. Keeping a battery fully charged at all times is the best way to assure it has a long, useful lifespan. Rule #2 is keep it bolted down- - - -bouncing around destroys a battery in a hurry.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!