automatic battery charger

Automatic battery chargers are not particularly cheap, however the pro-tection they afford against over-charging and possible battery damage is highly desirable. The circuit shown here is intended to provide an inex-pensive alternative to the commer-cially available fully automatic chargers. The idea is to take a simple battery charger and incorporate an add-on unit which will automatically monitor the state of the battery and cut off the charge current at the desired point, i.e. when the battery is fully charged.