Battery-operated handheld power tool, battery unit for a handheld power tool, system with the handheld power tool and a battery unit, charging device for a battery unit and system with a battery unit and a charging device

A battery-operated handheld power tool () having a receiving bay () for releasably receiving at least one battery unit () is proposed. The receiving bay () has at least four electrical contacts (K-K) for making contact with at least four corresponding contacts of the at least one battery unit (), wherein a load of the handheld power tool () is connected between a first contact (K) and a fourth contact (K), wherein a switch () that can be switched to an open and a closed switching state is connected between a second contact (K) and a third contact (K), and wherein a first cell arrangement () is connected in series with a second cell arrangement () of the battery unit () or a first battery unit () is connected in series with a second battery unit () via the switch ().