BATTERY CHARGING
Introduction
The circuitry to recharge the batteries in a portable product is an important part of any
power supply design.? The complexity (and cost) of the charging system is primarily
dependent on the type of battery and the recharge time.
This chapter will present charging methods, end-of-charge-detection techniques, and
charger circuits for use with Nickel-Cadmium (Ni-Cd), Nickel Metal-Hydride (Ni-MH),
and Lithium-Ion (Li-Ion) batteries.
Because the Ni-Cd and Ni-MH cells are similar in their charging characteristics, they will
be presented in a combined format, and the Li-Ion information will follow.
NI-CD/NI-MH CHARGING INFORMATION
In the realm of battery charging, charging methods are usually separated into two gen-
eral categories:? Fast charge is typically a system that can recharge a battery in about
one or two hours, while slow charge usually refers to an overnight recharge (or longer).