Winter has really started to set in here in New England with several days of temperatures not getting out of the 20’s. Thanks to some good preparations i’m not worried about the potential for snow, but I am learning some new things about driving the Model S during the winter.

Cabin Temperature

Cabin Pre-heatThe first order of business is dealing with the cold temperature for myself. This means pre-heating the Model S which I can do through the Tesla App (if I remember) or better yet have set to be done automatically for me via VisibleTesla.

I have my daily schedule configured in VisibleTesla and the heating system comes on 30 minutes before I enter the car in the mornings  and while its still plugged in from the overnight charge. This ensures I enter a warm car every morning and I don’t affect my range for the day — the best of both worlds!

The time I leave work is a bit more erratic so I usually use the Tesla App for that. When I start seeing the opportunity to get out of there I hit the app and start the Model S warming up for me. This does eat into my range, but thanks to the Model S’s abundant range, even with 100 miles of daily driving I have plenty of range to sacrifice a little for some comfort.

I enjoyed turning on the A/C during the summer months before I got to the car. But getting in a warm car in the winter is even better!

Limited Regeneration

Until this winter, the only times I experienced limited regeneration was after the couple range charges I did just before road trips. After a range charge there is nowhere for additional kW to go as your battery is full so your regeneration is limited for a while. I found that period to be very short though and the annoyance didn’t last that long as you just need to make room by using some of the kW.

Limited RegenerationWinter months are bringing a different experience with regeneration. When the Model S is cold it limits the regeneration ability as the batteries need to be at a proper temperature to take a charge. This means that most days now i’ve got my regeneration limited by the Model S.

The dashed yellow line in the regeneration are of the center display is telling you what your regeneration limit is. If its not there, congratulations you’re not limited, if its there, be careful. For those not familiar with the Model S complaining about limited regeneration may sound like some sort of efficiency complaint but the real issue is that when regeneration is limited the car drives very differently.

When regeneration is limited the car drives very differently.

Without the regeneration limited you can essentially do single pedal driving and you end up relying a LOT on  regeneration to slow the car down. This is more efficient and its a lot more enjoyable to drive that way. With regeneration limited you need to use your brakes a lot more and you need to be aware that you need to do that. The first few times I was driving with limited regeneration I found myself catching up quickly with the car in front of me even though I had taken my foot off the “go pedal.”

With regeneration limited you need to use your brakes a lot more.

The other thing i’ve noticed with the winter-induced form of limited regeneration is that it lasts a very long time.  I did some measurements over a few days and found that the regeneration limit rises almost linearly for the first 30 minutes and then improves at a better rate:

Limited Regen over time

From these measurements you can see that sometimes i’m driving for over 45 minutes and almost 30 miles before I get back to the “normal” regeneration behavior — thats most of my drive home!

Since I really dislike limited regeneration, i’ve been experimenting with approaches to avoid it. In the mornings i’ve found that ending my overnight charge shortly before I need to drive in the AM leaves the batteries at a good temperature from charging and I can avoid limited regeneration in the AM. This can be tricky since you want to get to your planned charge limit, but you don’t want to end too early. The first few times I ended too early and the batteries cooled back off before I got to drive. Here again VisibleTesla can help, but its an area that I wish Tesla would address directly — add scheduled charge END time and then have the Model S calculate when it should start or control the rate to end at the desired time.

Schedule your overnight charges to leave your battery warm and avoid the morning limited regen blues.

I’ve been experimenting with the after-work limited regeneration challenge but there’s no charging infrastructure at my work. Warming up the cabin does not appear to have any impact on regeneration so I seem to be out of luck for the ride home.

Higher Energy Use

Cold weather definitely affects energy use on the Model S. My tires, while great for winter, are less efficient — they’re not the low rolling resistance tires that came with the Model S. I’m also using extra energy for warming the cabin (despite my chilly 66 degree year-round setting). And the Model S is using extra power when needed to manage the battery temperature. Where before my average day was around 300-315 kWh, now my average days are 350-365 kWh or about 50 kWh more than the summer months. As I mentioned earlier, i’m also using my brakes more in the winter thanks to limited regeneration so thats going to add more wear and tear on them too in the winter months.

Right now our average temperatures are in the 30’s and it will be interesting to see how the Model S does when they plunge to the single digits. I’m in no hurry to observe that though.

Some of the factors above are out of your control, but one piece of advice Tesla provides is to use seat heaters to warm up more than cabin heat. The seat heaters apply the heat directly to you and are more efficient. So if you’ve got a more normal 72 degree setting in your car, in the winter try lowering it to 68 or lower and use your seat heaters more to conserve kWh.

I’m sure my first Winter with the Model S will bring other surprises, but even in the winter the Model S excels at so many things that its hard to imagine driving something else for these winter months.