Patent ID: 7932697

Claim:
A power tool comprising: a battery pack including at least one lithium-ion cell; a motor driven by electric power supplied from the battery pack; a current path connecting the motor and the lithium-cell, said current path including a first switch and a first FET; a battery protection IC electrically connected to the current path, the battery protection IC outputting a first detection signal when the battery protection IC detects that the current in the current path exceeds a predetermined current value and a second detection signal when the battery protection IC detects that a voltage of the lithium-ion cell is lower than a predetermined voltage value; said first switch being switchable between an ON state and OFF state depending on user operation; said first FET being switchable from its ON state to its OFF state responsive to the first detection signal or the second detection signal, whereby the current flows in the current path, when the first switch and the first FET are both in their respective ON states; and a second FET positioned outside of the current path, said second FET being connected to said first FET via a circuit, said second FET being operable, in response to an overcurrent or low voltage, to change its switching state, wherein when the current in the current path becomes lower than the predetermined current value, the first FET maintains its OFF state when the first switch is in its ON state after the first FET changes to its OFF state, and wherein when the voltage of the lithium-ion cell becomes higher than the predetermined voltage, the first FET maintains its OFF state when the first switch is in its ON state after the first FET changes to its OFF state.