Why in our University to use gem car ? Gem car is a vehicle powered by electric motor. Use electrical energy replace fuel instead of oil. Maximum power battery that can supply power is 72 V and charge 6-8 hour ,nevertheless, the gem car have battery 2 sets. Battery water made from lead can run around 8 cycles and if straight line run around 12 cycles . From battery connected in series 6V 12 Unit has 225 Ah, the time is used to charge total by equation