12V NiCAD Battery Charger Circuit Schematic

The figure below is a schematic diagram of a 12V NiCAD battery charger with a charging rate of 200mA/Hour.

Components List:

Resistors: 1KOhm, 68Ohm, 2KOhm, potentiometer 10KOhm

Diode: IN4001, 2xZenerIN752

Transistor: 2N2219, 2N2222

This NiCad battery charger circuit charges a battery at 75mA until the battery is fully charged and then reduces the current to a trickle rate. It will fully charge a dead/unpowered battery in 4 hours and the battery can be left in the charger indefinitely. To set the shutoff point, connect a 270 ohm/2 watt resistor between the charge terminals and adjust the potentiometer to 15.5V.

The input voltage of this battery charger circuit is 24VDC, you can use a universal power supply or a 24V lead-acid battery from your car.