The Truth Behind the Range of EVs
If you’ve ever owned an electric vehicle or you know someone who does, you’ve probably had a conversation about the range of these cars. You may have asked why they don’t go as far as they claim. The answer depends on a number of factors, but it all starts with the official test.
All cars undergo the World-harmonised Light vehicle Test Procedure (WLTP), which gives estimates for a vehicle’s range. Even petrol and diesel cars don’t go as far as the manufacturer claims, and they use the same test to calculate fuel economy. The main issue is, the test doesn’t fully replicate real world conditions.
While it’s also the same reason why petrol and diesel car ranges always differ to what the manufacturer states, the official economy figure is only one drawback. EVs have a little more to worry about as everything is powered by the charge it holds. Accessories, lights, heated seats, air conditioning and fans all drain the car’s power, which also reduces its range.
The range figures manufacturers are allowed to publish are dictated by the WLTP. It makes more of a difference with EVs because a drop in range can mean stopping for a greater length of time in order to recharge, which makes it more noticeable.
The other limiting factor for EV range is their batteries. Not their capacity, but their optimum operating temperature. EV batteries perform better in warmer temperatures and worse in colder conditions. Outside of this optimum range, the car has to use extra energy to work. Some modern EVs get around this issue by having efficient heating and cooling systems that keep the battery working at optimum temperatures, but this also requires energy. All energy used to control the battery’s temperature reduces the expected range.
This links back to the tests for the WLTP because they are undertaken at 23°C and 14°C. In the real world, the coldest weather we see in the UK isn’t 14°C, so this test already doesn’t cover actual conditions. In the summer, it can get especially hot - even hotter than optimum battery levels - which means that extra energy has to be expended to cool them.
To get around this problem, you can programme your leaving time into your car so it can get the battery to the right temperature, as well as the interior, so you’re using mains power instead of stored battery power. This, however, requires the use of an app or on-screen menus and advanced timing. In reality, most people probably won’t do this.
The plus side for EVs is their braking. The WLTP tests the car at speeds of 11.7, 24.5, 35.2 and 57.2mph and is designed to simulate real world driving with plenty of speeding and braking. This is good for EVs because they use regenerative braking to recharge their batteries, giving them more power.
The best thing to do is to look at the quoted range figures from manufacturers more closely. The main figure is the average from the WLTP test, but other figures are available that manufacturers don’t have to publish. These are based on other components of the test and can give EVs a low range figure (for low speed driving) and an extra high figure (for high speed use).
The extra high figure is best suited to gauge your range if you predominantly drive on motorways, while the low or medium range figures are a good gauge for range in urban areas. If these ranges aren’t available, ask the salesperson to see them so you can get a better idea of its real world range.
Ultimately, after the WLTP, an EV’s range will differ depending on, among other things, the number of passengers, what type of terrain and inclines you’re driving on and the external temperature.