In an access control system, a method and system for conserving battery life comprising an electronic control processor in a motor-driven locking subsystem for measuring samples of back electromotive force from a DC motor within the motor-driven locking subsystem. The samples of the back electromotive...http://www.google.de/patents/US7006799?utm_source=gb-gplus-sharePatent US7006799 - Energy saving motor-driven locking subsystem
