I removed 3 Duracell AA batteries from a portable radio because the radio stopped playing.
The batteries were on my desk for a couple of days, waiting to join all the other batteries
for recycle. While sitting at my computer desk this morning I heard a bang, and I could not
tell which area of the room it came from. A search turned up nothing, no failed electrical
equipment or lamps. The sound was startling but not ear-ringing. The banging sound was
followed by a very brief "ssssss" sound.

A couple hours later I picked up the batteries and saw a milky substance underneath the batteries
on the desk, and I immediately washed it off my hand. The batteries did not appear to be
moved from an explosion. The batteries looked relatively clean and there was no visible
sign of which battery leaked. I cleaned the desk area with water and a raised residue in the
shapes of 2 batteries remains.

I once had a musical keyboard permanently damaged after ignoring the batteries for a long time.
I have also observed a clock battery leaking that powdery stuff and the clock was still running.

Batteries...can't live without them; sometimes they are a pain.