Getting the hang of winter range calculations

I’d like to share two examples of range estimate calculations under winter conditions that were verified by actual trips. I used the same method to estimate the range at the beginning of the trip, and compared with the actual remaining range on the dashboard at the end of the trip. In both cases, the estimate was very close to the final dashboard range.

First example was a 57 Km trip. Initial state of charge was 10 bars. Range chart estimates for 10 bars @ 80 Km/h were 137 Km. Temperature was -2C, meaning 22% drop in range. We planned to use climate control throughout the trip to avoid fogged windows, which I estimated would take another 15%. So The initial 137 Km range minus 37% quickly became an 86 Km range. If the estimates were correct, that would still leave us with 29 Km to spare.

At the end of the trip, we made it home with 28 Km of range on the dashboard.

Second example:

– Round trip: 37 Km
– Starting charge: 10 bars
– Range chart estimate at 20C and 80 Km/h: 137 Km
– Outside temperature: 2C (-18% drop in range)
– Climate control on: -15% drop in range
– Final range estimate: 137 – 33% = 92 Km
– Estimate range to spare: 92 – 37 = 55 Km
– Actual dashboard range at the end of the trip: 55 Km (no kidding)

A couple of notes:

  • I used the final dashboard range measured after putting the car in park. Estimated range in Eco mode would be a bit higher, but you have to consider the fact that the last kilometer of the trip was done at low speeds, so things kind of balance out at the end.
  • The range chart estimate is based on constant speed, which was obviously not the case of either trip.
  • Outside temperature was not necessarily constant.
  • The method is clearly not very scientific but it gives me a fairly good estimate of what to expect. The formula will probably change once outside temperature dips below -20C, because that’s when the internal battery heaters kick in.
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4 comments on “Getting the hang of winter range calculations

  1. Hi Ricardo, welcome back form your trip! As we had a few days that were -26C I was wondering how many Nissan Leaf drivers did. As for me, well I caved in and gave up on the Nissan Leaf for now. Unfortunately my 120km daily drive was too close to being left stranded at work on a very cold winter day. My building will not provide power so I would depend solely on my batteries. Also, I apologise but I grew too accustomed to my perks in my car. I do not want to give up being able to drive at any speed to make it on time or use my heater or AC during summer. In short, the technology is not where I want it to be. I will only feel comfortable if an electric car offers 500 miles or more of charge. That way I definitely would not mind even if the car faces -25C weather without a Heat package lowering the battery range almost 50%. Also, I wanted a car that would allow me to travel as far as Toronto (190 km), spend the day and come back without having to worry to charge it up. It is just too new for me. Having said that and the fact Ford is discontinuing their hybrid SUV I went ahead and got myself a CUV for now, so that I have a newer car for when the electric technology is better. Once the 500 miles or even more is achieved, I will be the first in line. Thanks for all the tips though. It was definitely a life saver.

  2. I used the range chart for the first time on Sunday. It ended up being pretty accurate – I was off by 2km range. This was when it was -19 degrees and we went to IKEA. Its 17.5km one way (35km round trip). We charged the car to 100% before we left and came home with 36km range left. There’s what the cold will do to you!

  3. hi Ricardo,
    I noticed you have not been writing. when you can, describe what this winter has been like and how well the car is doing, especially after a couple of says with -23C. Until I get an electric car, whenever that might be, I am a follower of your blog and the technology.

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