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Researchers have developed various intelligent charging algorithms to charge batteries accurately, provide maximum capacity after each charge and increase overall battery life (number of cycles). But those algorithms are difficult, if not impossible, to implement using only discrete components. This is where microcontrollers come into play.
Charge time for nickel-cadmium and nickel-metal-hydride batteries has dropped from four to six hours a few years ago to just 15 to 30 minutes. Lithium-ion batteries are being charged today in just over an hour. As the time it takes to recharge a battery plummets, it is becoming more and more important to terminate charging accurately.
The older generation of chargers, based on discrete components, often terminated charging prematurely, resulting in a reduced battery capacity after each charge. For Li-ion batteries, even a slightly premature charge termination results in significant capacity loss. For lack of a good charge-control algorithm, these chargers also often overcharged the batteries, sometimes causing significant damage, the amount of which was dependent on the battery chemistry being used.
NiMH and Li-ion batteries are very sensitive to such overcharge. Temperature in NiMH batteries increases dramatically after the battery reaches full charge. This rise causes very significant damage to the overall battery life. In the case of Li-ion batteries, a slight overcharge-anything more than 1 percent-can damage the battery or pose a safety hazard.
With the emergence of many new battery...