Dave is absolutely correct, I check every battery I change coming out of a mod and coming off the charger. Only buy battery's from a reputable source and please follow all advice given here.Battery wrap ends should be checked every time a cell is installed or removed, or put on a charger. All it takes is a crack or a little wear that allows a short at the positive end. Whether the cell will short at that point depends on the design of the contacts on the device.