It all started with a handful of 1.2-volt NiMh batteries (AA and AAA size) lying in the back of a drawer. I was using them for my aeronautical GPS and didn't know which ones to rely on: some held the charge for just a few hours, others provided more than 24 hours of good and loyal service. To get a clearer picture, I started building a constant current (100 mA) discharger on a simple Veroboard card. I didn't know then that I was putting my finger in a gear that would allow me to return to my original profes