Abstract: A battery pack for a portable electronic device includes a case for carrying a battery. The case supports a charge sensing circuit carried by the case, the charge sensing circuit producing a discharge signal corresponding to a measurement of an amount of charge removed from a battery. The case also supports a processor responsive to the discharge signal from the charge sensor circuit to produce a signal corresponding to an amount of time prior to discharge of the battery based on a current rate of discharge and a display responsive to the signal to display a time period corresponding to the amount of time to discharge the battery based upon the current rate of discharge of the battery.

Abstract: A fast charging method and apparatus for secondary cells, especially for lithium ion cells. The charging process has two charging phases. In the first charging phase, a constant current is supplied to the secondary cell from a charging apparatus whilst monitoring the output voltage of the charging apparatus. The first phase terminates when the output voltage of the charging apparatus reaches a predetermined maximum voltage (e.g., 4.2 volt for a lithium ion cell). Then, in the second charging phase, the output voltage of the charging apparatus being monitored and constant current pulses of fixed duration (e.g., 10 seconds) are supplied to the secondary cell in a manner such that the duration of intervals between such constant current pulses is controlled to maintain an average output voltage of the charging apparatus at a predetermined average voltage (e.g., 4.2 volt for a lithium ion cell). The charging is terminated when the duty cycle of the pulses falls below a predetermined value.