Requirements for Overnight Recharge of Personal Electric Vehicles

EV driving and recharging were simulated with travel data from the 1977 NPTS. Full recharge times of four to sixteen hours were considered for EVs with ranges from 40 to 100 miles. Recharges in less than 16 hours were seldom found to be necessary for cars recharged overnight only. With a 16-hour recharger (83 percent of the simulated EVs received a full recharge, and 90 percent reached at least 90 percent state of charge). Little recharge energy would be purchased during the daytime and early evening, so time-of-use rates would not substantially penalize those with 16-hour rechargers. These and other factors in charger design are being systematically evaluated in a program of battery charger development sponsored by EPRI.