if the terminal voltage of the battery 13 varies in the final charge period also the depth of discharge is prevented from becoming excessively large as a result the useful life of the battery 13 can be prolonged from the foregoing description it should be readily apparent that the described charging and discharging arrangement is very useful in prolonging the battery life in a number of ways also ss has been described the battery 13 is a lead acid battery generally the lead acid battery holds a relatively large amount of electricity and is designed for general purpose use the lead acid battery is thus used in accordance with the described embodiment however those skilled in the art will readily understand that that aforedescribed construction and methodology can be subject to many variations without departing from the spirit and scope of the invention as defined by the appended claims as one example even though a lead acid battery can satisfy the need for large energy for the vehicle and low cost it should also be understood that the battery employed is not limited to the lead acid battery but may be a nicd battery or a silver oxide zinc battery furthermore the vehicle powered by the battery is not limited to one driven in a restricted area such as a golf course.