Driver Knowledge Tests

How much does temperature and weather affect the range of your electric vehicle?

While petrol-powered vehicles are affected by the temperature, battery-powered electric vehicles, or BEVs, are more affected. There’s a sweet spot for lithium-ion batteries at around 21 degrees C, and a few degrees above or below is no cause for concern. Where EVs start to be affected is when the mercury rises above 30C or below freezing, all other factors remaining equal.

Cold weather

The chemical reaction in EV batteries is slowed down in cold weather, so they need to be brought up to temperature to get the best performance. This draws some power from the battery unless you have your vehicle plugged into the power. Then, when you are driving, you’ll want to use the heater. Because there’s no petrol or diesel combustion, which generates heat that can be channeled into the cabin, any heat you want has to be created using battery power.

In either hot or cold weather, preconditioning can pre-heat or pre-cool the cabin to a comfortable temperature. Preconditioning is extremely useful if your windscreen is icy because it can melt that ice before you get to the car, and it will normalise the temperature of the glass to stop condensation forming. This is a useful safety feature.

If the preconditioning is done while plugged into mains power, this preserves battery life because you don’t need to waste the battery demisting your windows and heating or cooling the cabin. However, if it’s not, then it will reduce the range.

The ambient temperature will still affect the range, even if the EV is preconditioned. Expect to get 10-20% less range if the temperature is at freezing or below.

You can mitigate this by completing EV training.

Hot weather

Hot weather will trigger the batteries’ cooling systems which must draw power from the batteries to be activated. You may also want to keep the cabin temperature comfortable, which means using the air conditioning (saps power from the batteries), or opening the windows (creates more drag, therefore using more power).

Temperatures above 30C see a larger drop-off in battery performance. This can be mitigated slightly by driving slower.

Windy weather

Fighting against a headwind puts extra demand on your EV’s batteries, while driving with a tailwind will give you a small boost. The total effect depends on how aerodynamic your vehicle is from the front, and how much like a sail it acts from the rear.

Wet weather

The electric motors must push the tyres through any standing water on the road’s surface. The deeper the water, the more energy required to keep the wheels rolling.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

Posted in Advice