Team BeligerAnt's Tech Talk

NiCd and NiMH Battery Chargers

Simple constant-current charger

This charger uses only two components and can be used to charge battery packs from 100mAh to 20Ah(!), from 1.2V to any voltage you like!

There is a Javascript calculator to help you calculate the resistor value, input voltage and heatsink that you require.

It is a constant-current charger which can be used to charge NiCd or NiMH batteries at C/10 or C/8 rate.

A more sophisticated NiMH fast charger

This circuit is more complex, and will charge a 4.8V or 6V 150mAh or 700mAh pack in about 1 hour. The circuit diagram is linked above, for further details, email me. The data sheet for the MAX712 IC is available from the Maxim website.