Let it snow, let it snow, let it snow
As the UK and much of northern Europe is hit by heavy snowfalls, electric vehicle (EV) owners might be concerned about the amount of power their in-car heaters, lights and windscreen wipers are draining from the batteries.
But while winter weather could more than halve the range of some electric cars, manufacturers are working to find ways of keeping their vehicles going through the snow.
Conventional cars use heat from the engine to warm up the inside of the car but EVs have to transfer energy that would otherwise be used to power the motor, which can have a big impact on the distance the car can travel on a single battery charge.
‘Things like wipers, headlights, the radio, they use a minimal amount of juice but if you leave the heater on for your whole journey you will reduce [the battery life],’ says Alex Prince, mobile engineer for G-Wiz distributor GoinGreen.
‘If you get up to 40 miles in the summer, the combination of cold batteries and having the heater on can knock 10 miles off the range.’
For other models the effect can be even worse. According to Nissan’s simulations for the Leaf, ideal conditions can give a range of 138 miles while driving at 14°F (-10°C) through stop-start traffic with the heating on reduces the range to 62 miles.
Although the US Environment Protection Agency (EPA) lists the Leaf’s real world range at 73 miles, the proportional drop in Nissan’s own simulations suggests a range drop of over 50 per cent with the heating on. And similar figures have been quoted for other makes of car.
Batteries also discharge faster in cold weather because the chemical reactions inside them occur more slowly and less current is produced, so they more quickly reach a point where the current doesn’t meet the energy demands.
However, manufacturers are taking steps to limit the difficulties EVs have in cold weather, both through general improvement of battery life and energy-efficiency and more specific ways of tackling the issue of cold weather driving.
One of the Leaf’s solutions lies with its connectivity, which allows the driver to send a signal to the car via PC or mobile phone to begin heating the car before it is started.
‘This means that some power-hungry operations can be programmed to be carried out prior to removing the car from charge to maintain full charge for the journey,’ says Nissan’s design and technology spokesman, Matthew Loader.
In the G-Wiz, heated seats can reduce the energy used for climate control by as much as 75 per cent compared to a blower heater.
The car also has heater pads to warm the battery to the optimum operating temperature. Older models only do this when the car is charging but the new version allows the lithium ion batteries to warm themselves without being plugged in.
The limited performance of EVs in cold weather is certainly seized upon by their critics. But proponents will always argue that as most commuter journeys are well within the cars’ maximum range, a dent in the distance they can go often won’t matter.
Initial research suggests EV drivers are certainly aware of the problem. A study of the Mitsubishi iMiEV begun at the start of 2010 by the CABLED consortium of companies found that drivers made longer and more frequent journeys in the summer.
‘We’re not sure yet if that’s because they’re becoming used to the vehicles so range anxiety becomes less or if it’s a weather-related issue and the range is higher in the summer,’ says Neil Butcher of ARUP, who is leading the trial.
‘There was a noticeable drop in range in the cold weather we had in January and we’re waiting for the data to come back for this winter.’
As is almost always the case with EVs, there is still a long way to go before these issues are suitably addressed to convince the majority of the public that buying one is a good idea.
A common theme running through the manufacturers’ measures is to ask drivers to make small changes to their routine – getting the car ready slightly before they want to drive it – in order to maximise the time it can stay on the road.
Enthusiasts may embrace this novelty but as people often moan at even the smallest inconvenience when it comes to travel, perhaps automating these systems could help win over those concerned about being stranded in the snow.
But it’s worth remembering that Norway is the second biggest European market for G-Wiz manufacturer Mahindra Reva.
Electric vehicles also have one big advantage in cold weather, says Alex Prince of GoinGreen. ‘They always start first time.’