I was in the work/study program in high school my senior year. I walked into "Beetles, Buggies and Bajas" for work one day, just in time to see my boss unhook the battery charger from a battery that had been cooking for a while. Apparently, he did not turn the charger off, OR recognize that the battery was overcharging (gassing) pretty good. The spark created when he broke the connection ignited the hydrogen, and the battery exploded in his face.
He almost literally dove into the slop sink next to the bench, washed/rinsed for a good long time, and then went home for the day.
I do not know who got the most lasting impression, but I still remember cleaning up that mess, and vowing to never let it happen to me.
Best wishes on your recovery.