Was able to get Michelin X-Ice3 tires from a cancelled sale - because Tesla will still only sell the Pirellis. IMO these really ought not to be the default Winter tire. Thanks for the rx Doug - and heater description. Wondering if periodic on/off heating is in fact less efficient than constant low temp (17.5-20) - as HP might operate better when matching heatloss, rather than ramping up to sudden heavy loads - I usually toggle on to de-fog windshield but keep seat heat to stay warm (my trips are often over 600km)... I don't trust 'range mode' to really help max my range, which is why I drive with sorels and a down vest, toque and mitts! (the canadian range extender kit)
I've been told 6 kW for the pack heater by a Tesla employee. My own measurements have confirmed. You can get a rough idea of the power draw simply by looking at the dashboard gauge. More accurately I have measured the car's energy draw from a CS-90 charging station using an external meter. The CS-90 has more than enough power to fully handle both heaters at maximum draw. Using the remote app to preheat a thoroughly cold-soaked car at -20C, the car draws 11 kW. Running cabin heat only gives you half that. So it appears to be 5.5 kW for the cabin heater and 5.5 kW for the pack heater. Round numbers - 6 kW.
As for the heat pump:
1. At the Model S launch event in Fremont I asked an engineer and he said there is a heat pump. He didn't elaborate further.
2. I have also looked at screen photos from the touchscreen HVAC diagnostic mode before it was locked down - very informative.
3. Finally, from observation of the vehicle's operation: If you compare against the Roadster the Model S takes substantially more power when the car is cold, but once it warms up it takes substantially less power. Considering that the Roadster cabin is tiny and doesn't even get properly warm, the Model S has a lot more heating power for a lot less energy consumption. Thermodynamics tells you that all electric heaters have the exact same efficiency (exactly 100% - any losses come out as heat!); therefore the only way the Model S could be more efficient is if it uses a heat pump.
4. Dual mode is necessary because the heat pump won't work well with a cold soaked car. Thus the resistive heaters.
Do you have a source that confirms the 6 kW resistive heater and that there are indeed two heating modes?
Excellent work Doug...thanks for posting this!!!
LOL neroden, I've never had it that bad! But a good tip!
(1) Clean out the wheel wells. Certain types of sticky snow will accumulate in the wheel wells and reduce your range DRASTICALLY. Get a stick and clean 'em out.
This is the only tip Doug is missing.
Great post and excellent organization of information. Thanks for sharing!
Fantastic blog post, Doug...you have "written the book" on cold-weather driving. And I remember your original tips from the winter of 2012/2013, when many of us were learning this for the very first time! I am very glad to see Tesla improving the vehicle's features and capabilities (with both software and hardware) to deal with cold weather over the past two years.
Stevezzzz - tx for the tire note. Will change my update to get the Hakka R2.
Another of your excellent, information-packed blog posts, Doug; thanks for giving us somewhere to point newbies and the curious.
By the way, I've got an S85 on Michelin Xi3s and a P85D on Hakka R2s. Both are excellent winter tires for snow and ice driving; I give the nod to the Hakkas for dry pavement grip and stiffer sidewalls, so that when the roads are clear you can access more of the car's available power before the tires get squidgy.
Great blog post, Doug and bang on with my observations as well. With my more typical longer range driving patterns I actually leave Range Mode OFF all winter, but have it ON all summer (mainly to keep the a/c compressor down to a dull roar).
Another comment for extreme cold weather driving - add a couple of ounces of 91% isopropyl alcohol to your windshield wiper fluid to help clear the ice/snow off the front window. In extreme cold it keeps the fluid from freezing and helps clear the window faster. I use this in all our vehicles.
Thanks for the Range mode shut off tip - I wondered why my vehicle didn't warm as fast when on "shore power" in my insulated garage on the preheat mode!!!! - Fixing that tonight
Doug: thanks a lot a very good read and useful for me. Also liked your cold weather blog. Both very useful to me as a new owner of the "S".
Great info! Thanks.
I nursed our S85 through last winter on the Pirelli Sottozero IIs. It was embarrassing having to get a push to start it moving on a virtually flat surface covered with loose snow. With traction control on, the wheels wouldn't turn at all; with TC turned off, the rear tires just spun with even the lightest touch of the throttle.
The Michelin XIce3 tires that I have this winter are a huge improvement. I no longer have to look for a flat parking spot from which I can push the vehicle to get it started. They do squirm on moderate to hard acceleration and braking (the Pirellis didn't), but I have a lot more confidence in them when it comes to getting going, and keeping a $100K vehicle out of the snowbank/ditch.
When I first got the car I had the scroll wheel set to control the fan, but the auto fan control was massively improved in a firmware update a long time ago.
Ever since they fixed that I've had the scroll wheel set to temperature, like you. Very handy!
Also, once the car is warmed up, turning off the climate control doesn't really save all that much energy. It only takes 1-2 kW. I prefer just to slow down a little and stay cozy. (I've had too many Roadster trips freezing my ass off despite wearing long johns. Model S is soooo much more comfortable in winter!)
Great tips Doug! Thanks for writing, just switched off range mode. One little thing I've done for when it's really cold and centre console hasn't booted yet, is set right scroll to turn on climate, temp scroll up and down, super handy, and that way the wife doesn't see me shut off climate for extending range a wee bit I can attest to the statement that the Pirellis are crap. And yes, the car has encountered many situations where it refused to budge from a standing start, new snow tires on my next service! One question for you, why do you think tesla didn't insulate (thermal) the batteries for cold climates? Wouldn't it use far less energy to precondition that way, And even help keep cool in summer? What if like a chicken, tesla roosted on a bed of SM insulation when parked in my carport (using air susp to ride in and lower onto?)