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.
The 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!
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.
Winter 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:
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.
Thanks for all that work and data. Was surprised that the winter re-generation was postponed for that long a time frame. That VT Visible Tesla software appears to be really handy for using “shore” power to pre climatize the Tesla. I will make sure to get that software when I get my Tesla. Do you run VT software from your phone / laptop / PC? And does the device and software have to be running to kick off charge and or pre-heat / cool? I suspect it does. Well done and being a New Englander, like you, I value your opinion on the S during the bleak Winter season.
Thanks. I do run VisibleTesla on my MacPro and have it running all the time. Recently its been reliable. I have it set to warm up the car 30 mins before my normal departures during the week. Im playing with Range Mode now to see if that helps the pack warm up better.
VT does need to be running for it to do its work. I have my MacPro on all the time for things like new SuperCharger detections etc anyway.
Tesla Owner said:
I drove in some cold weather in Wyoming but I don’t remember my regen being limited nearly that long and it was really cold and really windy. Are you doing a full range charge before you leave home?
These are daily driving experiences, not road trips so I’m not doing range charges. But I am ending charge time near departure and pre-warming the cabin.
Thanks again for all your posts. I took delivery on my MS just before Thanksgiving and am loving the experience. I also live in the Boston area so this subject is of keen interest to me. Three comments related to the issue of pre-heating the battery:
In Episode 10 of his “News from the Frunk” video blog, Nick Howe states that heating the cabin air also heats the battery, apparently based on forum posts by others. Some comments seem to support that, one even referencing a statement by Elon Musk that this now occurs at any HVAC setting (vs. only on HI setting previously). I’ve not experimented on my own, but just want to point out the contradictory information.
I have started using Visible Tesla to manually schedule charging to end at a certain time, as you suggest. This involves starting charging with the application, reading the “Time Left” value (once it stabilizes), stopping charging, and then scheduling charging to start again at a time equal to my target end time minus the time-left value. Though a bit inelegant and time-consuming, this does achieve the desired result. (Implementation of this same method within the Visible Tesla application would be a welcome enhancement of that software.) Also, just to cover all possibilities, I also schedule the HVAC to heat the cabin air, too.
What I don’t understand is why Tesla doesn’t explicitly expose heating the batteries as a separate function just like heating/cooling cabin air and charging the battery. Linking battery heating to HVAC and/or battery charging is a highly suboptimal solution. There are too many times when external power is not available for charging, or the battery is already charged, or when having to heat cabin air in order to heat the battery is an unnecessary waste of energy and range. Hopefully there will be a software upgrade sometime in the not-too-distant future with this functionality added.
John: your suggestion of TESLA creating a winter battery heating function is excellent.
Nick lives in Florida so his comments are from reading more than experience. From my experience heating the cabin does nothing for the regen limit. Perhaps if I had the heat turned way up but otherwise it doesnt matter at all.
What does matter is charging/finishing a charge near departure time. Thats the only way i’ve found to reduce or eliminate regen. Again not having it for a while is inconvenient but not terrible.
It would definitely be nice if Tesla would let you schedule charge end time, or just tell it to warm up the battery for when you plan to leave and figure the rest out.
Thanks. I also think a summer battery-cooling function would also be needed for hot climates like Arizona, since operating the battery at elevated temperatures shortens its life. Ideally, one should be able simply to schedule the car to be ready to drive at a certain time, with the option to conditionally enable each function based on the availability of external power. At the specified time the battery would be charged to the set limit and heated or cooled to the optimal operating temp, and cabin air would be heated or cooled to the pre-set temp. Seems obvious to me.
Currently waiting on delivery of my Model S sometime in December (they seem to take a long time to get over to the UK). Winters in the South of the UK don’t compare with parts of New England but we usually get a few days of snow. My question is more to do with going down hills rather than up them. In my ICE car I engage a low gear to control the speed going down snowy or icy slopes. Does regen provide the equivalent level of control in the Model S? If there is no or limited regen due to a cold or full battery are the conventional brakes your only option for controlling your speed when going downhill?
On a related subject I recall Bjorn Nyland saying in one of his videos that the battery did get warmed up if cabin heating was turned on while the car was plugged in but that this did not happen if range mode was turned on. Does this match your experience?
The short answer is the regenerative braking is very much like downshifting in a standard transmission when regeneration is not limited by cold weather. I wrote more about that part here:
Going down a large mountain recently I went down the entire mountain without ever touching my brakes. In fact I had to set cruise control so as not to slow down too much:
For warming the battery when its very cold, while i’ve also heard stories of warming the cabin etc I have not found any of those to work with or without range mode. The best and only thing that has worked for me is charging right before you leave. So either time your charge start time so it ends near your departure time or do something like charge to 80% overnight then start a “top up” to 90% in the am. I found the former is the best if you have a fairly consistent departure time.
Also the “smart preconditioning” isn’t smart and I found it to do odd things at odd times and shut it off after a lot of trials.
Thanks, thats great to hear!
Thanks for your reply and many many thanks for the blog in general. It’s a great resource and an inspiration.