My local supermarket chain has a recycle container for batteries. Buy your new ones and drop off your old ones at the same time.
One day, Alexander (my 12 year old son) and I had an idea: how many batteries that people throw away are actually still good?
We asked - and were allowed - to collect the contents of the recycle box. The contents comprised AA, AAA, C, D, 9V and assorted button cells.
We tested the batteries with a multimeter, and found that:
- about 1/3rd were dead flat (eg 1.2V) or were leaking
- about 1/3rd were still useable in applications where a slightly lower voltage didn't matter (electric motor toys, LED torches that use a regulator, etc) - these were typically about 1.4V
- about 1/3rd were as-new - 1.5V plus.. some even 1.6V!
Pictured below is our current collection. It goes down as Alexander uses them up (mostly in toys); it goes up after we collect more from the recycle bin.