As much as I enjoyed this unusual technical info from GeekDad contributor Roy Wood, I was disappointed to learn that not all 18,650 things you can do with an old laptop battery are specifically listed in the article. Moreover, by a truly amazing coincidence, “18650″ turns out to be the part number for the most common size lithium-ion cell used in assembling laptop batteries.

Three 18650s are pictured above, and as you can see, they are slightly larger than AA batteries. Importantly, they are also much, much more dangerous, and Roy goes to great and appropriate lengths to emphasize that opening a laptop battery and extracting the cells for your own projects is very hazardous.

If you are competent to negotiate those hazards, however, and are interested in recovering 18650s from old batteries and putting them to use, Roy’s article is a pretty good starting place. The individual cells are very powerful, and since a single bad cell can kill the entire battery, there is potentially a lot of value to be recovered. [via Boing Boing]