Also, set the battery you wish to store on something that does not drain heat from it, like a cement floor: put it on a piece of wood or something else that will insulate it.
Cement floors seem to wreck batteries, even here in Miami, where it doesn't really get cold.
Semibodacious Transmogrifications a Specialty
1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)
"Time flies like and arrow, yet fruit flies like a banana"