An electrical energy storage device for storing electrical energy and
supplying the electrical energy to a driving motor at different power
levels is disclosed. The electrical storage device has an energy battery
connected to a power battery. The energy battery has a higher energy
density than the power battery. However, the power battery can provide
electrical power to the electrical motor at different power rates,
thereby ensuring that the motor has sufficient power and current when
needed. The power battery can be recharged by the energy storage battery.
In this way, the power battery temporarily stores electrical energy
received from the energy battery and both batteries can provide
electrical energy at the different power rates as required by the motor.
The energy storage device can be releasably connected to an external
power source in order to recharge both batteries. Both batteries can be
recharged independently to optimize the recharging and lifetime
characteristics of the batteries.