Schumacher PS-500-1A - Manual (Page 7)

7
STORAGE
Make sure the ON / OFF switch is in the OFF position when storing this unit.
If left in the ON position, the clamps could spark if they come in contact with
each other causing a short circuit which may cause the battery to explode.
For best operation, store at room temperature. Storing in extreme tempera-
ture conditions causes the battery to discharge quicker and reduces the
starting power of the unit.