Abstract

A system includes a prime mover, such as an automobile engine, having operative and inoperative states; an electrical load; an accumulator or battery for operating the load; and a control system for the battery. The control system includes: a self-holding keeping relay having contacts in circuit between the battery and the load and having a resetting coil to control energization of the load from the battery; a warning device; a detecting device and a detecting switch controlled thereby responsive to a fault condition in the battery; and a changeover switch responsive to the operative state of the prime mover for operating the detecting switch. The control system is responsive to a fault condition in the battery, such as overdischarge or low electrolyte, to prevent energization of the load when the prime mover is inoperative and to enable energization of the load and operation of a warning signal device when the prime mover is operative.