Abstract: At the end of am accumulator discharge process, the accumulator has a raised internal temperature. In order to be able to recharge it again, it is necessary to wait until it has cooled. The charging time is consequently significantly determined by the cooling time. To shorten the charging time, the invention proposes the installation in the accumulator of a temperature sensor and disconnecting the accumulator on reaching a predetermined temperature. Although it is still not empty, it then supplies no further current. However, it can immediately be recharged, so that the cooling time is rendered superfluous. Despite the shorter discharge time, the accumulator is consequently available over a longer period of time.