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3 tips to significantly increase range in winter and message for Tesla

Discussion in 'Model X' started by ML_X60D_Canada, Jan 26, 2018.

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  1. ML_X60D_Canada

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    I figured I would share some of my tips for increasing range in winter (for longer trips). We have an MX 60D, best car ever, do a ton of driving, and live in a very cold place (Montreal). We rarely have range concerns and more importantly, the more we drive our car in the winter, the better we understand how to affect range. So here goes. Don't be shy to correct any of my math/assumptions. Because folks on this forum tend to be :)

    First of, here is my understanding of why range can be an issue in the winter time:

    1. Cold air is denser, so drag is greater, 15C vs -15C translates to roughly 12% more drag. This is then multiplied by the cube of speed!
    2. Heating the cabin is expensive (2-6 kWh)
    3. Rolling resistance is usually higher in the winter time due to snow/ice/rain on roads and ice buildup on cars makes them less aerodynamic
    4. Finally cold batteries have higher internal resistance and this is elephant in the room! When I start my drive on a cold day (-15C to -20C). My battery will likely be the same as outdoor temperature (slightly higher). At some point this winter we stayed a full week at our cottage at -25C to -35C!. After about 1-2 hours of driving, the battery usually warms up (can be seen by the regen limitation disappearing) and within two hours you have full regen (battery is now >15C). If you have observed this in your car, you probably also noticed that your consumption was at least 2X rated. The heating of the battery comes from the onboard heater (if you have range mode off) but also comes from the battery's internal resistance. Numbers: a 1200 lbs battery needs 19 kWh to go from -15C to 15C (1200lbs*54(temp delta)/3412(BTUs per kWh) and 25 kWh to go from -25C to 15C. So in my MX 60, about half of the capacity can be lost to waste heat. This is far more significant than the 3 other factors listed above.


    3 tips for getting near rated range in the winter time (sorted by most impactful):
    1. Preheat. A lot. I will preheat (with range mode off) for up to 4-5 hours If I know that I need the range. Ex for a 250 KM drive (My rated is 310KM). If you have a 6 KW charger, you will need 4 hours to to generate 24 kWh or enough to bring your battery to ideal temp. I like to keep my climate setting at 18C when preheating so that the bulk of the power comes from shore and not from my battery. Preheating like this has a night and day effect on range. If you can park indoors, even better. Preheating gives you a thermal storage equivalent of 25+kWh. Try it.
    2. Try to not exceed 20-30 KW of power. Specially with a cold battery. So don't accelerate hard, don't regen hard (coast vs regen). This will again limit the power losses in the battery. Bjorn has a great video on Youtube showing how to very quickly heat up your battery by accelerating and decelerating like crazy. Yes, do the EXACT opposite of what he is doing :) What is incredible in his video is seeing how quickly you can heat up a battery by having a heavy foot. That's 10s of kWh lost in minutes ... So go easy. This has also made me a much better/zen driver. My Bernese Mountain dog in the back really likes my driving :)
    3. Drive slower. Because of drag being much greater in winter and because of v cubed. CUBED!!!!

    If you are still reading, here are some more tips:
    1. Use seat heaters. It's by far the most efficient way to heat humans in a Tesla
    2. The "% Battery left" in the navigation system needs about 10 minutes of driving to show an accurate estimate, but it works very very well and I use it as my "budget" for fun things like speed and heat
    3. Pick your charging stops in a way that your battery is warm upon arrival. This will speed up charging. Ex, I charge at a stop just before arriving to my ski location (fast warm charging) VS charging apres ski (cold battery slow charging).

    Elon/Tesla if you are reading, here is my wish list for some software:

    1. Conditioning feature: I want to be able to set my departure time at, say 7 AM, hit "yes" on the popup warning me that this will result in more electricity cost, and have the car (using only available shore power) preheat the battery, then the cabin, then top off the battery so that by 7 AM, I have the optimal conditions and the best best range ever. Heck, I would like the battery heated to 35C-40C, so that this extra heat can be used as cabin heat for the next 1-2 hours. Can you imagine getting better than rated range in -20C!!! Come on Elon.
    2. Make chill mode more chill and make chill mode chill Autopilot. I avoid using excessive acceleration and deceleration to improve range. It would be great if Autopilot didn't take my speed setting as a do or die challenge. Allowing +-3 KM from set point would improve range drastically by eliminating needless (60%-efficient-at-best-regen AKA regen) and high KW bursts on small hill climbs. We love Autopilot. I think it's incredible that Tesla was able to develop it so quickly and it's amazing how much safer and easier it makes our drives but my wife and I now do this voiceover/if Autopilot could talk thing and it goes something like this: *deep 8 year old eager boy voice* "You want me to follow that car.... Yah Yah, i can do that i can i can. Go go go... Oh no, oh no, regen regen regen. No wait, wait, i got this, i got this, go go go...." And we're like, Chill dude... Driving under an overhead sign (circa Q1 2017, he doesn't do it anymore): *the same 8 year old with the deep voice* "My mom always said life was like a box of ch... AHHHHH THING!!! THING THING, break break br... oh oh oh wait, where did it go?" And we're like, no Boo (car's name) it was just an overhead sign. It's okay, we still love you.

    Hope that was helpful...

    Elon is you are still reading:

    1. This one is more complicated but can be very impactful for range. I have arrived to destination with 0%-1% left on my battery on MANY occasions with no worries about running out. I use my speed and zen driving as my variables to manage my "budget". It would be great if my Tesla can automatically reduce max power to help automate what I do manually. Guaranteeing arrival time and using the full capacity of the battery. Right now, power limitations only kick in when the battery is very low (too late). Having such a feature would allow users to use up the 10%-20% of the battery that they usually put aside as buffer. To cancel this feature, the user can simply kick down on the accelerator and the limitations would be reset...
    2. Unlock Boo and all other 60Ds or just Boo :)
    3. Platoon feature: All the hardware and most of the software is already in place to do this.
    4. Also Good job, you are killing it.
     
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  2. jajabor

    jajabor Member

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    What's Boo?
     
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  3. iluvmacs

    iluvmacs Member

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    Jesus, 4-5 hours of preconditioning? That's surely a waste. I find 30 minutes is more than enough to get the battery (and cabin) up to temperature, and that's having just done it in a Wisconsin winter (we recently had a cold snap where it was about -20°C for a few weeks).
     
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  4. DriverOne

    DriverOne Supporting Member

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    The name of his car, I suppose.
     
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  5. Ruffles

    Ruffles Member

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    My BMW i3 had departure time and I miss that feature. It was great to get into a toasty car every morning with 100% charge ready to go. I imagine the trick would be to balance conditioning with charging. With the X having so much range, I don't need to charge it every night. I just want to plug it in to condition.
     
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  6. _jmk

    _jmk Member

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    Excellent thoughts, IMO. Wonder why this Thermal storage is not used? Sounds very plausible it could indeed work.
     
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  7. TJtv

    TJtv Member

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    30 minutes is good for regular days driving where you don't really care about range. However if you're driving long distances on cold days and every rated mile is important to you - then he showed the math of how 4-5 hours of preheating can really help. Clearly you end up burning more total energy than you would if you had only preheated for 30 minutes, but that extra energy burn is from shore power and if it makes the difference between being able to make a drive without stopping to charge and NOT being able to make the drive then it may be worth it.
     
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  8. dedicatedtek

    dedicatedtek Member

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    too funny because it's true.
     
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  9. thefortunes

    thefortunes Member

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    Schedule your charge to complete 30 minutes prior to your departure. Then preheat for 15-30 minutes (depending on ambient temperature).

    Preheating for more than 30 minutes is absolutely nuts. You are basically heating the space around your car in addition to your interior and battery (which, if you schedule your charge correctly will already be warm). You are NOT creating 24kWh of "thermal storage" you are just wasting electricity.

    Finally, turn range mode on when you start the drive so the battery heater does not kick in (which it shouldn't if you time your charge properly). I have a 30 minute commute daily. I leave a warm garage in the morning, but drive home with a 10-12 hour cold-soaked battery. My Wh/mi is consistently within 5% on those two drives.
     
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  10. ML_X60D_Canada

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    You bring up a good point. By doing this you will have some heat loss. But I'm not sure that the battery loss is very significant. A quick calculation based on 4 hours, average 15 C delta, 40 sqft (rough battery area) and a 1/4 of air between the cells and the aluminum base plate (based on teardown photos) yield a total loss of 0.8KW. You will certainly loose more from the cabin being warm for such a long time so keeping the cabin setting low would help...
     
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  11. SpiceWare

    SpiceWare Member

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  12. beths11

    beths11 THE LONG RANGER

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  13. Roadster2010

    Roadster2010 Member

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    This is a very interesting discussion!
    I live in Tidewater Virginia, so not so applicable to me, but I like the science of it all.
     
  14. teslcls

    teslcls Member

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    Our Niki tends to have a mind of his own at times, too - kinda like riding a horse - you occasionally need to do something with the reins.
     
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  15. wweiss

    wweiss Member

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    #15 wweiss, Jan 27, 2018
    Last edited: Jan 27, 2018
    Just plan ahead, finish a slower overnight 40A charge to 90% so that it's done just when you leave. All will be warm. Weston, CT
     
  16. Glitch

    Glitch Member

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    Actually when you charge overnight you can lower the number of amps used, unfortunately this settings can only be done within the car, if you lower it to 8 amps for example your charge will take much longer but the battery will be on the desired temperature.

    If Elon is listening enable the charge option within the app, for example a fast option use max power of the charger or low option if you have the time during the night. Other option give me the option to open en close the windows via the app.
     
  17. Stratusbill

    Stratusbill Member

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    Great analysis. Drag is proportional to the square of velocity.
     
  18. Gary and Rachel

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    Elon/Tesla if you are reading, here is my wish list for some software:


    1. Conditioning feature: I want to be able to set my departure time at, say 7 AM, hit "yes" on the popup warning me that this will result in more electricity cost, and........


    You made a great post on how to get more out of your X Boo.

    You do not have to wait for Elon to fulfill your requests for better charging and warming features. Its here now if you have an Android phone, ( don't know about apple) go to play store and d/l app Dashboard for Tesla. This app will do what your asking for. We've been using this app for a year now and don't even think about charging and having car fully charged just before we need it all warmed up and charged to our setpoint.

    Now it has features that are free but to get fully customizable presets you will need to pay once a couple of bucks for. We loved the app so much the first few days that we bought almost all the upgrades to support the software. Less than $20. oo if I remember correctly. I have no connections with this program, I do have a Model X however that now takes full advantage of these great features now.

    Elons guys have done very little to advance the Tesla App in the almost two years we have owned our X and I would think Tesla would add all these Dashboard features and more to existing tesla app. But till then try Dashboard out, I can tell you will really enjoy it.

    Gary
     
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  19. tmxninja

    tmxninja Member

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    A slight variation.....I would like to see a feature where I can tell the car: "I am going to supercharge in 30 min, please warm up battery." There is only so much entertainment at a supercharger, so it would be nice to warm up battery on command.

    Also , I find heating the cabin on a very cold day 15F outside, 66F inside consumes about about 25% of relative miles.
     
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  20. Webby

    Webby Member

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    Helpful analysis, thank you! I took my kids on a 2200 mile holiday adventure up through Vermont, Erie PA, Snowshoe WV, during the major snowstorms this Christmas/New years.

    One unique issue I encountered with winter range was departing Snowshoe with a full lukewarm battery at 5500’ elevation. Big mistake. I should’ve left room for regen on the 2000’ descent, and heated the battery for many hours as OP suggested. Our 75D can just barely make the drive to our NC home without stopping, but in this case the battery got so cold on the descent (without regen) that I got a red message indicating that the battery temp was too cold, and my projected range dropped by 50%!! Eventually during the drive the battery warmed and regained range, but still with a 25-30% deficit. We had to deviate to Lexington Supercharger to make it home, instead of arriving with a 15% cushion as normal. We’re here again this weekend so I’ll be experimenting with a longer trickle charge to keep the battery warm, and depart with ~90-95%% charge. And it’s warmer (40°) Will report back.

    Also one really helpful winter driving upgrade I made this year was insulating the Pano roof of our MS75D (Bjorn Nylands idea) with thin reflective foamboard cut to size and held up by the Topfit sunshades. Big improvement in comfort in 0°-20°F driving, allowed me to keep the thermostats substantially lower for the drive (kids were still comfy in their boosters). Much of the comfort improvement feels like radiant reflection and my head is close enough that it’s tangible. Also notable is the Pano roof ices over and doesn’t melt, so definitely less heat loss thru the glass and lower energy usage heating the cabin. My wife demands cabin heat typically, so the fact she was happy at 65° is a huge difference. Not sure how OP could do this in his MX60D...I think Bjorn did the Pano insulation in his older MS, IIRC?
     
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