I don’t exactly know that I needed the whole of this 5’32” video to grasp the concept: if you drop an battery it will bounce if it’s empty, it won’t if it’s full.
Empty. Full. Really I suppose I mean empty as in used up, full as in still has a charge. The folks behind this video call them good batteries vs bad batteries, though that just seems harsh.
Watch the start for proof and a demonstration of how you don’t have to throw the batteries on the ground to test this. Then carry on for an examination of why it may all be true.