Abstract: A power supply system, for example, for use with a portable personal computer, includes a smart battery pack and a charging system. The smart battery pack is provided with a dedicated microcontroller for controlling the charging level of the battery charger system. In particular, the status of the battery including the voltage and temperature of the battery is applied to the microcontroller along with a signal representative of the current load demand of the computer system. The micro controller, in turn, provides a control signal in the form of fixed frequency, variable duty cycle pulse width modulated (PWM) signal for controlling the charging level of the battery charger system. The duty cycle of the PWM signal is used to regulate the charging current supplied by the battery charger. In particular, the DC value of the PWM signal is used as a reference to control the charging current of the regulator to provide a variable output charging current with a relatively wide current range.

Abstract: A battery charging control apparatus for controlling charging of a secondary battery has a FET which is so controlled that the supply of a charging current is suspended after being forcibly supplied to the secondary battery for a predetermined charging time, when the voltage of the secondary battery has risen to a level equal to or higher than a predetermined reference voltage, and, after the battery voltage has come down to the reference voltage during the suspension of the supply of the charging current, forced supply of the charging current is commenced again, thus realizing intermittent charging. The FET also is so controlled as to vary the above-mentioned charging time in accordance with the progress of charging of the secondary battery.

Abstract: An emergency stop warning system for an automobile with a hydraulically operated brake system and that includes an electric power supply, a warning sound emitting electrically operated horn connected with the power supply, a normally open fluid pressure actuated switch electrically connected between the power supply and the horn and hydraulically connected with the brake system; that the hydraulically actuated switch is set to close and cause the horn to sound when fluid pressure in the braking system is increased to cause the automobile to decelerate and stop at a faster than normal rate.