Do-it-yourself battery capacity tester

During a recent trip to a theme park, I discovered that a couple of the nickel metal hydride batteries that I brought along for my digital camera didn’t work for more than a minute or two. Preferring not to be in that position again, I decided to test the capacity of all my rechargeable AA’s so I could demote the bad ones to less critical applications.

I wrote up a page describing the simple device I built using a couple of resistors and a wall clock. It looks kind of like a bomb, but works great! Check it out!

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