While driving an electric car recently, a constantly changing figure on the trip computer caught my attention. It was km/kWh and kWh per 100 km (or Wh per km). Having being used to ‘km/litre’ over the years, this came as a surprise.
What is kWh?
Short for kilowatt-hour, kWh is a unit of electricity. For example, 1 kWh is when 1,000 watts of electricity is used for one hour (a 100-watt light bulb operating for 10 hours, or a 500-watt air cooler used for two hours, or a 1,000-watt hot water geyser used for one hour, and so on).
In the Indian electricity cycle, 1 kWh is one unit of electricity (priced in the range of Rs 5-7 in some states, and more in others).
What is kWh in an EV?
An electric car’s battery storage is measured in kWh. Tata Nexon EV has a 40.5 kWh battery, while Audi Q8 e-tron has a whopping 114 kWh battery. The smallest is the one in MG Comet EV (17.3 kWh).
To top up a car with a battery of 40 kWh will need 40 units of electricity.
More kWh, more range?
Yes and no. Driving range depends on various factors, like power produced by the electric motor (more power means lower range per kWh), weight (more weight means lower range per kWh), the way the battery cells have been packaged and their operational efficiency, useable battery power (100 kWh doesn’t mean all can be used), and so on.
Is km/kWh fixed?
It’s the same as petrol/diesel cars. One driver may drive a Maruti Suzuki Alto in a way that it returns 22 km/litre, and another may drive so poorly so that the car returns only 15 km/litre.
Similarly, electric cars are driver-specific. One driver might be able to run an electric car for, say, 200 km on a full battery pack, while another driver may be able to take the same car more than 300 km. A balanced pressure on the accelerator pedal (refraining from immediate acceleration and braking) will lead to more efficiency and longer driving range, and vice-versa.
So the next time you drive an electric car, keep an eye on the trip computer — the higher is the km figure in km/kWh, the longer will be the range.
