Patent ID: 8283889

Claim:
A charging device ( 10 , 100 ) of a power tool ( 16 ), comprising: a charging unit ( 12 ); and at least one interchangeable, rechargeable energy storage unit ( 14 ), in the form of an interchangeable battery ( 18 ), in which each energy storage unit ( 14 ) has first contact means ( 24 ) for contacting the corresponding power tool ( 16 ), wherein each energy storage unit ( 14 ) has additional contact means ( 38 ) for contacting the charging unit ( 12 ) in such a way that the charging unit ( 12 ) charges the energy storage unit ( 14 ) via the additional contact means ( 38 ), both when the energy storage unit ( 14 ) is connected to the power tool ( 16 ) and when the energy storage unit ( 14 ) is disconnected from the power tool ( 16 ), wherein each energy storage unit ( 14 ) has a sensor ( 44 ) emitting a sensor signal (S, S 1 , S 2 , S 3 ) relating to the energy storage unit ( 14 ) and evaluated by both the power tool ( 16 ) and the charging unit ( 12 ), with each of said emitting of the sensor signal and evaluation of the sensor signal performed with a measurement procedure, wherein the first contact means ( 24 ) of the respective energy storage unit ( 14 ) convey the sensor signal (S, S 1 , S 2 , S 3 ) to the power tool ( 16 ) and the additional contact means ( 38 ) convey the sensor signal (S, S 1 , S 2 , S 3 ) to the charging unit ( 12 ), and wherein the power tool ( 16 ) has an evaluation and detection means ( 48 ), which detects from the sensor signal (S, S 1 , S 2 , S 3 ) whether the charging unit ( 12 ) is currently charging the energy storage unit ( 14 ) connected to the power tool ( 16 ).