CHARGE MAINTENANCE SYSTEM FOR LEAD-ACID BATTERY

A charge maintenance system for a lead-acid battery includes a charger, a voltage monitor, and a load/switch series combination, all connectable in parallel across the battery terminals, the switch and the charger being under control of a microprocessor. The battery is initially loaded for a predetermined time period, or until the battery voltage drops below an absolute minimum reference level during a loading cycle, and the system stores the lowest battery terminal voltage occurring during the loading cycle. After a predetermined delay following the loading cycle the charger is activated to charge the battery until it reaches a maximum charge level. Then, if the stored lowest battery voltage level is below a predetermined reference level, the loading/charging routine is repeated, otherwise it is not and the battery is considered good. If the stored lowest battery voltage level remains below the threshold for ten consecutive loading cycles, the system indicates that the battery failed the test but could be subject to retest. If the stored lowest battery voltage level is below an absolute minimum reference voltage level after three consecutive loading cycles, the system indicates that the battery is bad and should be discarded.