Posted this question on another HD website and no help, maybe here. 1982 FXLR with a two month old Ultima Thunderbolt (sealed) direct replacement battery. While riding the bike it backfired and quit with lots of smoke and/or vaporized battery acid coming from the bike and at the time too busy trying to get the bike to the shoulder to notice where the smoke was coming from and I notice the oil in my tach was boiling. Once home I found that the battery had exploded, battery was dry and the sides were expanded. Have done some troubleshooting with a volt/ohm meter and a visual inspection and nothing so far. It would seem to me a massive discharge that would cause the battery to explode there would be a component that would look like toast, but nothing so far OR maybe the battery internally shorted out, I have not seen or heard of that happening but maybe it is possible. Any suggestion as to what happend or where to look would be appreciated.