and the reaction slows down at lower temps. I did misunderstand your original post, sorry. Still, in a cold climate(ie up north) I would think the concrete would actualy be warmer than the ambient air temp as it is in contact with the ground which doesn't get as cold as the air, correct? Unless you just had a prolonged cold spell and the ground is cold soaked and the air warms up some, then the reverse would be true. I've stored bats on my concrete floor here in TX and never had a problem with them myself. Guess the moral of the story is jusy get a battery tender and leave it on the battery to keep it healthy for the duration of storage.