Battery monitoring circuit

Abstract

A battery monitoring circuit provides information as to the level of electrical energy remaining in a battery for determining an appropriate charging rate for the battery from multiple available rates. Such information is obtained without the need for measuring battery voltage and temperature during operation of a battery operated device or prior to the recharging of the battery. Each one of a plurality of representative values is assigned to represent each one of different current levels obtained from the battery while the battery operated device is operated in different current consuming states. The representative values are totaled for providing a measure of the total current consumption of the battery operated device for all periods of operation. In accordance with the measure of total current consumption for the periods of operation, representing the level of discharge in the battery, the battery is charged at one of the multiple available charging rates, i.e., fast, standard or trickle. While the battery is being charged, a count value derived from totaling the representative values is portionally reduced in accordance with the charging rate applied to the battery. As the count value decreases, the charge rate also decreases to a charge rate associated with the count level. The battery charging time is advantageously reduced thereby and an increase in battery life is achieved by limiting the application of only the trickle charging rate to a fully charged battery.