Originally Posted by
Winemaker
MCR01
I'm curious. 22 liters of petrol is about 16.5 kg providing about 45 MJ/kg, so about 740 MJ total energy. Assuming 25% efficiency of a piston engine, that's about 185 MJ of available energy. Lithium batteries (middle range) energy density is 0.6 MJ/kg. So, assuming 100% efficiency of the electric side, that means that to equal the energy of the petrol, one would need a battery pack weighting 185 kg. How could this possibly work? Have I made a maths error?
Very true but you have to consider the complete package of IC engine and fuel source so even if the battery is heavy the motor is lighter, example 300hp motor 15kg but it does rotate at 20,000 rpm so needs a gear box. But you are correct at the moment batteries are to low in power density, the break point seems to be 500W/h/Kg still heavy but feasible, once they hit 2.5Kwh/Kg then IC engines are totally finished this will happen.