If a battery
expands or bulges in cold weather, it is because it has frozen. This will damage the battery
and render it junk.
can be frozen if it is discharged and subjected to freezing temperatures. The acid in a battery is partially converted to water when the battery is discharged. Reconverted to acid when it is charged. It is very important to store lead acid batteries in a charged state, do not allow a battery to sit in a discharged state for any period of time (in cold weather it will freeze). This will allow the plates inside the battery to oxidize or scale up and decrease the capacity of the battery, resulting is reduced power output and life of the battery.
Batteries can last anywhere from 2 years to 10+ years. I just replaced (today) the battery in my 2002 Chrysler for the first time so this one lasted 12 years. The battery in my wifes Jetta only lasted 3.5 years, so you never know
And, no, it should not vent in this condition, but, I have seen frozen batteries crack the case and acid could leak out the cracks when the battery thaws.