Bouncing battery test...

I'll bet I know why bad batteries bounce.

I'll bet as a battery ages, gases build up inside the case and slightly expand it. I'll bet that the bottom of the case is slightly, very slightly, convex rather than flat, and that causes the bounce and the roll over.

Maybe someone could take a metal ruler or straight edge and see if the bottom of the battery is slightly convex indicating the pressure.

- ww