Patent ID: 7656130

Claim:
A battery charger to charge a battery assembly wherein the battery assembly can be a battery assembly of a first kind and a battery assembly of a second kind, comprising: a power supply section that supplies charging current to the battery assembly, a charging voltage detecting section that generates a variable reference voltage, the variable reference voltage being a function of the charging current, a detecting section that detects a temperature-representing voltage representing a temperature index of the battery assembly, and a high temperature detecting section that compares the variable reference voltage with the temperature-representing voltage of the battery assembly, the high temperature detecting section in communication with a controller that stops the power supply section from supplying the charging current to the battery assembly so as to finish charging the battery assembly when the temperature-representing voltage of the battery assembly reaches or exceeds the variable reference voltage during a charging operation, the variable reference voltage varying during the charging operation according to the charging voltage of the battery assembly.