Pretty much everything I just said in the title. To test if a battery is good or not. Hold up. Actually just thought of something. Let me clarify. I don’t mean car batteries, laptop batteries or smart phone batteries. This only applies to regular double and triple AA’s. For the love of god don’t be throwing car batteries on the floor, watching to see if they bounce or not.
Right, back to it. It all has to do with how heavy a battery is. Typically, a dead battery will bounce when dropped. Whereas a full or partially full battery won’t.