Backup electrical supply, for automobile central locking system, has backup battery mounted in electrical circuit with capacitor so that in case of loss of supply from battery, backup supply can actuate electrical lock during its discharge

摘要

Backup supply is battery (14) mounted in parallel with main battery (10), and has electrical lock (2) fed from battery. Backup supply is mounted in electrical circuit which includes capacitor (22) so that in case of loss of supply from battery, the backup supply charges capacitor so that when fully charged it can actuate electrical lock during its discharge. Backup supply mounted in parallel with battery is electrically isolated in absence of central locking actuating command. The backup battery is electrically isolated by diodes (16,18) from the rest of the electrical circuit. The diodes are mounted in opposition and are fitted between the battery and the backup battery. The central locking circuit includes a square wave signal generator (34) and inductance (32). A transistor (36) is fitted between the backup supply and a capacitor.