Lithium Battery Charger

This battery charger circuit is used to recharge the rechargable lithium battery. The circuit comes from Molicel.

Lithium Battery Charger circuit diagram

Charging is accomplished with a constant current of 60 mA for AA cells to a cutoff of 2.4V per cell, at which point the charge must be terminated.

The charging system shown is designed for multi-cell battery pack of 2 to 6 series connected cell or series/paralel arrangements. It is essential that all cells assembled in the pack are at an identical state-of-charge (voltage) before charging. the maximum upper cut-off voltage is 15.6V (6×2.6V). The ICL7665 from Maxim is a voltage monitor with dual over/undervoltage detection.

The ICL7665 warns microprocessors (uPs) of overvoltage and undervoltage conditions. It draws a typical operating current of only 3uA. The trip points and hysteresis of the two voltage detectors are individually programmed via external resistors to any voltage greater than 1.3V. The ICL7665 will operate from any supply voltage in the 1.6V to 16V range, while monitoring voltages from 1.3V to several hundred volts.

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