EV Cold Weather Performance

Last updated 2002.11.29


For some reason, many people seem to think that EVs won't work in the cold. (That appears to include the major automakers such as General Motors and Honda who are only leasing their electric cars in California and Arizona.) However, electric cars can perform quite well in the cold. The electric motor prefers to be cool, and cooling air is blown through the electric motor in some EVs. The motor controllers also require some cooling capability. Lead-acid batteries do lose a lot of capacity when they are cold, but this is easily remedied by keeping the batteries warm using insulation and battery warmers.

Several techniques are used for keeping the windshield and passengers warm, including fossil-fueled heaters and electric heaters.

Environment Canada has conducted studies on at least three EVs at their Environmental Technology Centre in Ottawa, ON, Canada, which have shown that with simple battery heating and insulation, the performance of the electric cars is not significantly affected by cold weather. One of these vehicles, a 1987 VW Jetta converted to electric by REV Consultants, experienced a range reduction of just 0.4% after cold-soaking for 42 hours at -17 degrees C (about 0 degrees F) compared to its range measured on the same dynamometer at 20 degrees Celsius (about 68 degrees F). The tests were conducted using the EPA FTP-75 LA-4 cycle. This test mimics a typical commute trip with numerous stops and starts, and speeds up to 90 km/h.

I have driven my electric car at temperatures as low as -37 degrees C (about -34 degrees F). Once the lubricants moved enough to loosen up, it drove normally. While the windshield defroster had a little trouble keeping up that day, so did those on many of the gasoline-powered cars I saw out that day. Unlike them however, I had no worries about my car starting or dying on the road due to a frozen gas-line.

Given the prevalent misconception that electric cars don't work well in the cold, let's have a look at what we have learned to do to make gasoline and diesel powered cars work in below freezing temperatures:
* build engine blocks with frost plugs;
* install block heaters to keep the engine warm enough to start (using as much electricity just to start the engine as an electric car might use to completely recharge);
* use different formulations of gasoline and diesel fuel for cold weather;
* use gas-line anti-freeze to prevent gas-line freeze-up;
* use radiator thermostats to help the engine warm up faster (but leaving the passenger cabin cold until the engine has warmed up);
* use auxiliary (electric) heaters in the passenger cabin until engine heat is available;
* let the engine run for 10 to 30 minutes before starting out on a trip to let the engine and passenger cabin warm up;
* change to less viscous winter grade motor oils (e.g. 5W30);
* install winter grill (radiator) covers;
* use glycol or alcohol based engine coolants (anti-freeze), which have to be tested as part of that winter tune-up;
* use oversize starting batteries;
* install battery warmers;
* maintain a shared fleet of service vehicles to help start vehicles in cold weather;
* carry booster cables and quick-start...

Still think it is electric cars that have a problem with cold-weather operation?


REV Consultants on EVs and Cold Weather Performance

The Hudsons operate a Solectria Force in Wisconsin year-round. Check out the Hudson's EV page to learn about their solar-powered, cold-weather EV. I especially like the photo of their EV parked in front of an outdoor thermometer. (That's 6 degrees Fahrenheit.)


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