Once I volunteered at a large tech non-profit. Between projects, I took over an unused desk in the sysadmin team cave. After lunch one day, I heard a loud noise

Once I volunteered at a large tech non-profit. Between projects, I took over an unused desk in the sysadmin team cave. After lunch one day, I heard a loud noise. I went to the cave door - it looked out over a large cubicle farm. There were now a dozen fires burning over a forty foot diameter, along with little bits of smoldering cubicle wall. Someone had apparently removed the battery from a laptop, plugged it into a bench power supply, and then gone off to lunch. It exploded in their absence. It gave me an instant respect for li-ion batteries, plus a small concern every time I fly in a small metal tube full of a couple hundred laptop and phone batteries. But several hundred used laptop batteries, with no balancing, in my garage, mounted on wood. NO FREAKING WAY EVER.