Motor-driven vehicle

In a motor-driven vehicle utilizing power stored in a secondary battery as a source of motive power in which part of vehicle braking is achieved by regenerative braking by generating electrical energy absorbed by charging said secondary the battery, wherein a charging capability of the secondary battery by regenerative power can be guaranteed, a method of regulating a state of charge of the secondary battery while the secondary battery is being charged by an external power source, comprising the steps of:

• entering a charge mode, and determining a remaining quantity of charge in said secondary battery based at least on a temperature of said battery,
• calculating a target charge quantity, charging said battery until a state of charge becomes equal to the target charge quantity,
• when state of charge becomes equal to the target charge quantity, replacing said charge mode by a sleep mode and measuring at least a temperature of said battery periodically as determined by a timer, judging on each occasion whether the temperature has decreased or increased,
• if the result of judgment corresponds to an increase, returning to the step of target charge quantity calculation,
• if the judgment finds that the temperature has decreased, shifting said mode to a discharge mode,
• in said discharge mode, determining a remaining charge quantity as a function of at least the temperature of said battery, and when said remaining charge quantity in said battery is such that a charge quantity corresponding to an amount of regenerative energy for braking of said motor-driven vehicle cannot be received by said battery, calculating a target discharge quantity,
• and performing discharging of said battery until said target discharge quantity is reached, and then returning to periodically measuring at least a temperature of said battery.