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Driving Your EV This Winter

Posted November 14, 2017 by Roseanne

James McKemey, Head of Pod Point Insights Team, has given us some advice about driving an EV during the cold wintery months ahead of us.

So, winter is on its way...

These clear nights lead to bracing star-gazing opportunities, frosty mornings, pet cats spending longer indoors and your EV losing some efficiency. Let’s explore the latter phenomenon…

While winter road conditions do have a negative impact on efficiency (e.g. slipping wheels, added resistance and driving through rain etc), the more significant issue is the need for heating.

Energy for Heating

One of the myriad joys of electric motoring is being able to pre-heat your car before you get into it. Indeed, if there’s one thing that justifies the stereotype of EV drivers being smug, it’s when they shut the door of their already warm, automotive cocoon and use just the wipers to remove the last of the melted slush/water from their windscreens. Seriously, once you try it, you’ll be smug too.

But heating takes energy, energy that would otherwise be used to propel the EV forwards. How much of an issue does this cause?

Pre-heating while plugged into a Pod Point will not reduce the range of the vehicle, but it will increase electricity consumption from the supply. However, when not charging, heating your EV will impact range. The higher the difference between the background temperature and the desired temperature in the car, the greater the energy requirement. This is true for both heating and cooling, but since this author lives in the UK, he’s seen more energy requirement from heating than from cooling!

How the Difference Shows

Heating adds to the energy consumption of a static EV. You’ll note at times of peak heating that even if your car is stationary it uses a little bit of power, as if you were making it creep along.

If you do a series of short trips with parked periods of sufficient length for the car to cool to an ambient temperature, you’ll see a relatively significant reduction in your miles per kWh, e.g. ~30%. However, these short journeys match the top-up model well, particularly when you can find a charge point at the destinations, meaning there is no real increase in range anxiety.

Longer journeys are the ones more likely to cause concern, but the impact of heating on these journeys is proportionately much less significant, e.g. ~10%. This is because it requires less energy to maintain the temperature in your car when it covers these larger distances in a single trip, than it does to heat it from ambient temperature. Ergo, more of your energy is used to propel the car forwards.

How Bad a Problem is This?

It can be a surprise how much of an impact cold weather has on your miles per kWh, particularly with short trips. Once you get the hang of it, however, it makes little material difference, particularly if your vehicle range is well in excess of your typical journeys.

Another way of thinking about it: the market with the most dominant electric vehicle uptake (with 48% of new cars sold in October 2017 having a plug socket) is Norway. Believe us, the Norwegians are making very good use of their EV heaters!

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