If you run out of a charge on a pair of AA batteries but have some AAAs laying around, reddit user Its738PM suggests using a strip of aluminium foil to convert the AAA battery into a AA battery.To get this to work, all you need is a AAA battery and some aluminium foil. Wrap up a ball of foil and stuff it into the case of your device where the battery's negative terminal connects. As long as you have enough foil to fill in the gap, your device should turn on. This method works great in a pinch if your mouse battery dies in the middle of a work day or if a torch goes out during a storm. It's not a permanent solution, but it works great for short periods of time.