Convert AAA Batteries Into AA Batteries with Tin FoilS   To get
this to work, all you need is a AAA battery and some tin 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 if your mouse battery dies in the middle
of a work day or if a flashlight goes out during a storm. It's
not a permanent solution and should only be used in a pinch, but
it works great for short periods of time.  LPT: out of AA
batteries? Use AAAs and tin foil in a pinch. | Reddit