Patent ID: 8373392

Claim:
A battery system for supplying electrical power to a load, the battery system comprising: a battery; and a battery protection apparatus configured to protect the battery from over-discharge, the battery protection apparatus comprising: a voltage controlled switch configured to establish an electrical connection between the battery and the load, the voltage controlled switch comprising a relay, and a bipolar junction transistor; a voltage detecting unit for detecting a battery voltage of the battery and generating a detecting voltage according to the battery voltage; and a stop switch connected between a base and an emitter of the bipolar junction transistor; wherein when the detecting voltage is lower than a predetermined value, the bipolar junction transistor is turned off to disable the relay, such that the electrical connection between the battery and the load is discontinued; when the detecting voltage is higher than the predetermined value, the bipolar junction transistor is turned on to enable the relay to establish an electrical connection between the battery and the load.