A protection circuit device for protecting a secondary battery from an overcharge and/or an overdischarge has first and second terminals, across which a charger and a load are alternatively connectable. A first switch and/or a second switch may be provided in series with the secondary battery between...http://www.google.com.au/patents/US5896025?utm_source=gb-gplus-sharePatent US5896025 - Secondary battery protection device from overcharge/overdischarge
