We were boosting a grain auger once,and the old man was using the tiger torch to warm up the ole Brigg's crankcase,when he got a little close to the battery.There was chunks of battery blown through the side of the burn barrels a good 100ft away,but we were both lucky and never had anything hit us.The only part of the battery left was the bottom part that was sitting in the angle iron battery tray.Ever since then,i've been mighty cautious with sparks or flame around a battery,whether it's being charged or not.I'm not the smartest guy on the block,but i figure that was our 1 lucky go around with an exploding battery,and i'm not willing to try out another battery explosision.
The guys saying use a grinder or sawzall around a battery,need a slap upside the head,whether they think they're being funny or not.In other words if you can't help the man out,keep your damn mouth shut