There’s irrefutable literature which says that electric motors are significantly more efficient than their Internal Combustion Engine counterparts. Most mass-produced engines can only extract 40% of the energy in its fuel for forward propulsion.
This means that more energy is lost as heat and as sound, than as momentum produced. In contrast, electric motors are up to 90% efficient, i.e. 90% of the energy that goes into the battery packs end up being used for drive.
But if electric motors are more thermally efficient than engines, why don’t EVs have similar ranges to their petrol-powered counterparts?
What’s The Most Thermally Efficient Modern Engine?
Engines have actually become significantly more efficient in recent times. With turbocharging and hybridisation, less energy has been lost to its surroundings. The pinnacle of this efficiency is the Mercedes F1 V6 Hybrid, which has a thermal efficiency rating of 50%.
It also sports technologies that are slowly trickling down into Mercedes’ road cars, perhaps in an almost-vain bid to stem the EV tide.
Energy Density
To understand why EVs currently do not have the range to match their dinosaur juice-fuelled stablemates, we first need to understand energy density. See, the overall efficiency of a vehicle is dependent on not only drivetrain losses, but also the source of the propulsion.
Sure, motors convert more energy into motion, but current battery technology isn’t mature enough to match the energy density of fuel. Scientists have worked out that petrol has an energy density rating of 47.5 MJ/kg.
A lithium-ion battery pack, the same kind you’d find fitted to many modern electric vehicles, has a rating of just 0.3 MJ/kg. For electric cars to have the same range as a similarly-powered ICE vehicle, you’d need battery technology to allow for a 5-fold increase in energy storage – something that just isn’t possible for the mass market at the moment.
How Are manufacturers Making Up For This Difference?
Truth be told, EVs are at the stage where you’d be comfortably able to travel a week’s worth of mileage on a single charge. In a bid to further customer acceptance, manufacturers have equipped their vehicles with ever-faster charging speeds, with some car makers opting to future-proof their offerings by allowing their products to charge at speeds that no present commercial charger can deliver.
Other innovations in this field include mixed chemistry batteries, which utilise different types of battery cells for to allow for rapid charge/discharge when needed, and decent energy storage capacity. Battery swap stations have also been touted as an alternative, and so are wireless charging lanes.
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