Usage counter for portable jump-starting battery unit

摘要

A usage counter has input terminals connectable to the terminals of a jump-starting battery pack. The counter has an IC comparator which generates an output signal when battery voltage drops below a predetermined reference level. If the output signal persists for a predetermined time period, indicating an attempt to jump-start an engine with the battery pack, an IC timer is triggered to output a count pulse which is inverted and then counted and displayed by an IC counter/display circuit. The usage counter circuit is powered by the battery pack and has a Zener diode which provides to the IC circuits a limited supply voltage which is unaffected by voltage spikes which might appear at the battery pack terminals. A capacitor maintains the reference voltage level despite momentary drops in battery terminal voltage.