Patent ID: 8183836

Claim:
A lithium battery pack, comprising: at least five lithium battery cells connected in series; a first protection circuit, which is connected to at least four lithium battery cells out of the five lithium battery cells to monitor each voltage of the four lithium battery cells respectively, outputting a first signal when the voltage of at least one of the four lithium battery cells is less than a first over-discharge voltage; a second protection circuit, which is connected to at least one lithium battery cell, which is different from the four lithium battery cells, to monitor the voltage of the lithium battery cell, which is different from the four lithium battery cells, outputting a second signal when the voltage of the lithium battery cell, which is different from the four lithium battery cells, is less than a second over-discharge voltage; a switch connected to a current path of the plurality of lithium battery cells, the switch turning off and the current path being cut off when the first signal or the second signal is outputted; and a dead time means, which is connected to the second protection circuit, wherein said first protection circuit further monitors the current flowing through the current path and outputs a third signal when the current goes over a predetermined current; wherein the switch turns off and the current path is cut off when the third signal is outputted; and wherein the second over-discharge voltage is greater than the first over-discharge voltage.