How to discharge a number of old LiPo batteries

Most of these Lithium Polymer batteries were about 6 years old.

I cut off the connectors I wanted to keep and then poked holes in them with the garden fork. There was a bit of smoking, a nasty sweet smell and the occasional few sparks. But nothing very exciting.

Most were probably quite flat to begin with. A couple were well charged, but still no fires. One was a not-very-old 3-cell 2200mAH with one faulty cell. It failed after being run too low.

The next step was to soak them in water for a day or two just to finish the job and make sure they are cool before putting them in the rubbish.

The bubbled from the holes for a while as the water soaked in and reacted with the goo inside.