Battery-powered tool capable of detecting discharged battery pack

In order to prevent a battery pack (9) from being overly discharged during use in a power tool (1), a discharge voltage limit circuit (10) is provided. The circuit (10) disconnects the battery pack (9) from the motor (12) when the voltage of the battery pack (9) falls below a predetermined level. However, the circuit (10) is operable only when the main switch (4) is OFF, that is, when no load is imposed on the motor (12).