Winter’s effect on range for the Model S

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Weather conditions affect fuel efficiency and range for all cars. When your range in an electric vehicle is already relatively short and “refueling” is not as readily available as stopping at a local gas station the impact can be much more important to understand.

Over the month of January I studied the impact of weather on the range of my Model S. I’ll get into the details but on average my range was 40% less than the rated range that Tesla provides.

Average range can be about 40% lower in the Winter. With an average maximum range of about 160 miles on a full charge.

Collecting the Data

I recorded the rated range or percentage at the beginning of the day and at the end of the day as well as the reported kWh used and the actual miles driven. I also tracked the average temperature of the day and put it all in a table:

Range LogFrom the data you can see that my results were anywhere from 21% more use than rated all the way up to 57% more use than rated.

Results

Plotting this data of range versus temperature gives an interesting chart:

Plotted Range Log callout

Here you can generally see a trend towards improved efficiency as temperatures increase but the one big outlier stands out. It turns out that day the roads were covered in snow and ice. Taking out that point shows a better expected picture of temperature on range:

Range Log TrendlineUsing the trend line we can see that the outlier we had from before at 57% should have been more like 32% if the roads had been clear. So the snow and ice affected the range by an extra 25%.

Snow and ice on the roads can affect your range by an extra 25%.

With other larger outliers there are similar stories. For the 30% impact at 14 degrees, that was a single trip out and back (~50 miles) and the Model S was plugged into the wall prior to departure. While outside temperature was low, the garage temperature was higher. Warming your car up from shore power prior to taking a trip also improves your efficiency.

Warming your car up from shore power prior to taking a trip improves your efficiency.

The 35 degree, 21% impact data point was 93 miles of driving but all back roads whereas the other trips were mostly highway. Slower speeds can offset your cold weather efficiency loss.

Driving at slower speeds can offset your cold weather efficiency loss.

Summary

Using the data above and a calculated trend line I came up with the table below. This table is showing the actual maximum range i’d expect to get out of 85kW battery which has a rated range of 265 miles:

Winter Range Table

Note that the table below assumes a full (range) charge. If you charge to 90% you need to take another 10% off the numbers. My “normal” day of driving is 100 miles which puts me right on the edge on the worst days (very cold with snow/ice).

In the Winter your real daily usable range is more like 143 miles for the 85kW models, 112 for the 60kW model.

All of this analysis is just based on data I collected on my car over a single month of varied winter weather. I found it really eye opening to see my Model S rated range go from 265 to a real world average of 143 miles in the winter (90% charge, 40% range degradation). For the 60kW model this would be 112 miles.

Fortunately Tesla appears to be placing Superchargers within these winter ranges so that their use in the winter is still possible, although on bad days in the 60kW models I think it may be a very close call for drives like the one from the Albany, NY supercharger to the Brattleboro, VT supercharger (82 miles).

What can you do with this knowledge?

  • Expect on average to use 40% more power in the winter.
  • Expect to lose about 10 miles of real range for every 10 degree drop.
  • If the roads aren’t dry expect to lose up to 25% more range.
  • Plan your charging and driving accordingly — don’t cut it close.

I hope this information has helped you understand the effects of Winter on the range of the Model S. If you have your own data, observations or questions i’d love to hear them in the comments below.

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