CHARGING AHEAD

“An EV sends around 95 percent of its stored energy to the wheels”

Elardus Mare, Waterford WA

As an experiment, I put 10.6 litres of petrol into my car, timing the filling with a stopwatch. It only took 18 seconds to get that much fuel into the tank.

With energy density of roughly 34MJ/l, the 10.6 litres of unleaded represented the same amount of energy as in a fully charged, state-of-the art Tesla Model S 100D. The rate of replenishment for my petrol car compared with the best that the Tesla could ever manage is a few orders of magnitude higher though: 100kWh in 18 seconds works out to be a mind-boggling 20,000kW of filling power! No wonder, then, that even a very powerful Supercharger needs a theoretical 48 minutes to top up the Tesla’s battery with the same amount of energy as I added to my petrol car in just seconds.

The saving grace, of course, is the fact that in terms of efficiency, EVs are in a different league to petrol cars, with about 95 percent of the batterycontained energy expected to make it to the wheels compared with only about 25 percent of the energy in a petrol car’s tank.

It results in an energy multiplier of 3.8 in favour of the EV.

“An EV sends around 95 percent of its stored energy to the wheels”