Mythbusting the world of EVs: do lights and wipers kill your range?

MYTH: “lights and wipers kill your range”

It’s a dark wet night and you’re gripped by range anxiety. How much better it’d be, you think, if you could do without those power hungry headlights and wipers. Ah well, there are street lamps, so perhaps you could get by on only sidelights, and running the wipers on intermittent.

Nah, don’t worry, because they make little difference. Your screenwipers on full speed only draw about 100W – they have a 12V motor that runs less than 10 amps. So you’d need to run your wipers for 10 hours to use even 1kWh of battery energy. Many or indeed most electric vehicles nowadays have LED lights and they draw even less power, so although you might have them on for longer than the wipers, they still aren’t a concern.

More of a current draw might be the demisting, especially if your car doesn’t have a heat pump. You’ll have the air con running to dry the air and the resistive heater to warm it. But if you hit the max demist button, the system should clear the screen in a couple of minutes. Then you can shut off the air con and turn down the fan – and volume of warmed air – to a dribble just to maintain a clear view. At least unless you have a pack of big wet dogs steaming away in the back.

More likely to staunch your range, or your fuel economy in an internal combustion car, is the energy that is absorbed by tyres in clearing the water and creating spray. This can be a 5–10 per cent penalty.