Have you ever spent ages swapping batteries in and out of your remote control or other battery-powered device to determine which ones still have some juice?
Here is a theory that will make that frustrating process so much simpler: drop them on a hard surface and see if they bounce.
According to electrical engineer Lee Hite, a used battery will bounce far higher than one that has only just been taken out of its packet.
A good battery has a gel-like substance while in a battery that is on its way out the substance is solid. The gel absorbs the energy when your battery hits the hard surface whereas when that gel has solidified it cannot move and the whole battery then bounces.
This video shows you just how it’s done.
When all else fails, this trick will have you identifying those fresh batteries in no time.