Circuit for supplying energy from a battery to an energy-using device

A circuit for supplying energy from a battery to the load of an energy-using device is provided wherein the circuit provides for notification to the operator of the device that the remaining energy of the battery is low. The notification is provided at a time when sufficient energy remains in the battery for the operator to perform certain essential tasks. The circuit includes a battery having a plurality of cells connected in series, a first portion of which have a higher deliverable energy capacity than a second portion of the plurality of cells. The circuit further provides for sensing a characteristic of the battery indication of the remaining deliverable energy capacity lower deliverable capacity cell portion and for switching the circuit from a first mode of operation wherein energy is delivered to the load from all of the cells in the plurality to a second mode of operation wherein the energy is delivered to the load from only the higher capacity portion of cells. Switching is accomplished in response to the sensed characteristic indicating a low level of remaining deliverable energy capacity in the battery. Energy delivered to the load in the second mode of operation may be used by the operator to perform certain essential tasks before the device becomes inoperable for lack of energy.