Easy Nickel Cadmium Battery Charger / Discharger

I built this simple charger / discharger for 3.7 volt Nickel Cadmium cordless telephone batteries. It could easily be scaled up to charge larger Nickel Cadmium battery packs. Those of you who work with these battery packs know that they must be completely emptied of charge before they can be recharged. This device makes that procedure easy.

step 1Materials Needed

You will need a number of simple materials and tools for this project. They include: A wall transformer,or power supply; mine is 3.7 volts. The output of your charger wil…

step 2Wiring

Connect everything together as shown in the diagram; run a wire from one terminal of the wall transformer to one of the clips - it doesn't matter which one; you'll check th…

step 3Charging

With the charger set to charge and the transformer plugged in, use a voltmeter to determine the polarity of the charger and mark the clips accordingly. Unplug the charger …