[prairieschooner]

Had this last year and best I could figure was that it had frozen. Here's the deal, I attended a Seminar that was put on by Interstate Batteries. The guy putting on the seminar stated that a Flooded Lead Acid Battery could Freeze if Discharged, then when a Charge was Applied it Could Explode.

The other thing that I have seen is that if there was a Loose Connection it Could have created a Spark at the Terminal While Charging, Batteries Produce Hydrogen Gas While Charging and a Spark Can Ignite the Gas. I have seen many Exploded Batteries over the years while doing my inspections as a a Marine Surveyor and typically it was a Loose Battery Cable. And yes a Dead Cell could Ignite the Hydrogen Gas as well.

***Get some Baking Soda ASAP and Naturalize the Battery Bay. Then Wash with Soap and Water to ensure that it has been cleaned properly again ASAP!! The Baking Soda should Neutralize the Battery Acid but what the heck might as well clean everything.

Good Luck, this is a great reason to consider AGM Batteries since they are Sealed and Reportedly do Not suffer from Freezing.