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Wh/mile specifically for M3 LR AWD with 19" wheels

Discussion in 'Model 3: Battery & Charging' started by ultrainstinct, Sep 27, 2019.

  1. ultrainstinct

    ultrainstinct Member

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    Location:
    SanJose
    Model: Model3 LR AWD
    Mileage: 1000
    Wheels: 19" Sport
    Average Wh/mile: 360

    I've been driving my M3 for about a month. I know the 19" sport wheels have a 5-10% efficiency hit (crazy amount by the way) compared to the aero wheels, but I'm still getting a crazy high Wh/mile for standard drives. I'm not driving erratically and the AC is on but at 72 with the fan set to 3 or 4. Driving 20 miles at 65-75mph I average 360 Wh/mile. Tried this many times as it's my route to work. So even though the actual distance from home to work is about 20 miles, it takes away around 30 miles of range from my battery. It's so frustrating to see this. If this is expected, the GUI should be updated to reflect the actual range with non-aero wheels. Why would you display the expected range of a car that doesn't reflect your customized car with non-aero wheels? If this is not expected, then I don't know what's wrong. Perhaps I should get a diagnostic from Tesla service. I feel like in actuality the 310 miles is really something like 260 miles for LR AWD 19" and more people should be aware of this when deciding to upgrade their wheels.

    So I'm curious, what is everyone else's Wh/mile with the same configuration as me? LR AWD with 19" wheels? Are we all in the same boat? Is it just me?
     
  2. ultrainstinct

    ultrainstinct Member

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    Actually I just did the math and a lifetime average of 360Wh/mile is equivalent to 206 mile actual range. Pretty pathetic.
     
  3. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Your lifetime average is 360Wh/mi? It’s not clear what you were quoting (you said this is what you get going to work...).

    It’s not useful to quote a one-way efficiency since elevation change can make a big difference. I get 330Wh/mi on my way home, and about 130Wh/mi on my way to work.

    360Wh/mi for a flat drive at 70mph is a bit high.

    Are any of your tires wearing excessively? Really bad toe angle could hurt efficiency and prematurely destroy tires.

    But we really need to know your lifetime efficiency or typical round-trip efficiency to say more.

    Make sure tire pressures are 42-45PSI.
     
  4. mikeskuro

    mikeskuro Member

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    It’s alignment time! Something doesn’t sound right.
     
  5. ultrainstinct

    ultrainstinct Member

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    Sorry, let me clarify. One way trip from home to work is 20miles. Round trip is 40 miles. Round trip to work and home I get around 360Wh/mile and the route is flat both ways. Lifetime it shows 330Wh/mile. I've had the car since the beginning of September and have about 1000 miles on it, mainly for work.

    Tires are at 45PSI. I can't tell if they're wearing excessively as they're brand new but perhaps I should have them looked at.

    Any other recommendations of things to check for or is this expected for LR AWD 19"?

    Makes me sad seeing a bunch of other people getting around 230Wh/mile while I'm significantly higher
     
  6. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    #6 AlanSubie4Life, Sep 27, 2019
    Last edited: Sep 27, 2019
    Yeah, it sounds really bad. I would check the tires first (use a tire depth gauge and compare them all, and look for unusual wear patterns on the inner and outer edge of the tread (you could take good pictures and post them here I suppose)), I guess. A few things to try before bringing it in to have alignment checked:

    1) Turn OFF climate control for your work round trip (press and hold the button until it turns off). Monitor the usage with that. (Should not make much difference at this time of year especially with recent cooler temperatures.) If you must use it, be sure to turn off the AC and turn the temperature setpoint down well below outside temp so heat is not being used.

    2) Do not use the brakes for a trip to/from work. Only use regen (except use the brakes below about 5-8mph to come to a complete stop).

    3) Enable chill mode temporarily. This does NOT improve your efficiency at all, all else being equal, but will limit you a bit (and improve your efficiency) just in case rapid acceleration is a contributor.

    You should be getting comfortably below 300Wh/mi for your described drive to/from work at this time of year. I don't have your configuration; I have the stickier 20" wheels/tires, and I average about 280Wh/mi in mixed freeway/city driving with plenty of brisk acceleration. But those tires are much less efficient than the 18" and 19".
     
  7. kailm

    kailm Member

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    19s are for looks for sure. 18s can give you as low as 200wh/mi on LR.
    Drag at high speed is significant on the 19s/20s. Also they are heavier so rotational mass issue there not only drag.

    Although 330 seems excessive, but your only at 1k miles. Drive on chill if you want lower wh/mi.
     
  8. TimothyHW3

    TimothyHW3 Member

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    #8 TimothyHW3, Sep 27, 2019
    Last edited: Sep 27, 2019
    I explained some of the issues that you have in here. You can read my post there

    Lost 40 miles range on a 11mile regular journey?? New Model 3

    But to summarize your case. You have to understand that you car is rated at about 241Wh/mile (75000Wh or 75kWh battery capacity divided by 310 miles)

    This is mostly achievable at constant pace at around 50-55mph. The thing is - the LR AWD 18 and LR AWD 19 or even Performance are rated the same 310 miles. While these are achievable, as you mentioned, depending on the speed and surface etc. there will be a difference in consumption if you drive these 3 cars all on the same road at the same time.

    Having said that, your 310 miles or 241Wh/m on AWD 19 I believe are achievable at around 45-50mph constantly. So you have to factor in your higher speed. Same as gas car. There is also a huge difference wether you drive at 65 or 75mph. I think at around 65mph you should be avg. around 250-260 Wh/m depending on the surface, weather and wind and at constant 75mph Bjørn Nyland has averaged 283Wh/mile with the 18", with 19" slightly more.
    So as you can see, your consumption is fairly normal.

    And like I said in my comment on the other post - at 3-4 HVAC on AC on constantly, you are looking at around 2-3kW extra consumption(kW not kWh!). Either turn the AC off and use the wind from the manual system with higher number even 7-8(doesn't affect consumption at all) or turn on Auto AC, because it will lower the consumption once it gets to temperature.

    Also, to really measure your range, start a trip and go to the Energy menu. The trip gauge will give you expected % at end and consumption will give you the current consumption at the speed along with a more accurate remaining range, based on that consumption and not typical rated range as in the battery indicator.

    Hope this helps you and others, because I see a lot of confused people. Maybe we can gather all these posts into one.
     
  9. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    I followed you up to here. The OP was getting 360Wh/mi round trip in San Jose, which has not been especially hot. Max speeds sounded like 75mph, average speed probably closer to 40mph. So there is at least an 80Wh/mi discrepancy.

    You’d have to have it on maximum cool constantly to get to this level. Definitely AC could be a significant effect, but at a more typical average wattage of 1kW steady state, at an average of 40mph, that only adds 25Wh/mi (1000W/40mph). It does not explain the full 80+Wh/mi discrepancy.

    It’s possible that is all it is, but I think not that likely given the terrible efficiency - but easy enough for the OP to do a trip without AC/heat and compare the results.

    This is a really bad result for the AWD at this time of year in California is my point. While possible, it does not look normal, unless you are sitting in traffic in 100 degree weather with the AC blasting (which is not what was claimed).
     
  10. TimothyHW3

    TimothyHW3 Member

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    #10 TimothyHW3, Sep 28, 2019
    Last edited: Sep 28, 2019
    Bjørn Nyland does the test on fairly perfect conditions at constant speed. This is why the 290Wh is optimistic and just a reference. He also used 18". So if we assume OP wasn't driving at constant speeds and had some traffic, had head wind, we can assume 300-310 with the 19", without factoring HVAC due to constantly being on 4! am also a bit reserved when people post speed and consumption on forums, because more often than not there is some discrepancy from what they are saying and the reality.

    As for HVAC, I have the test in my video. The system hovers around 1.2-.1.9kW at fairly low speeds below 3. Check it out. When I fire it up to 7-8-9 on a 11kW, I have seen it go to 5kW! This will settle down, but will not go lower than 1.5-2kW unless you enable Auto. Because at Auto it might get a higher speed initially, but it will go to speed 1 fairly quickly and stay there. If you keep it at 4(or 7 like in the other thread) the consumption is higher and constant.

    I also think the consumption should be around 320-330 tops, but there are factors we don't know of, maybe also tires and tarmack, so I would say it is a bit high, but also probably normal. I just wanted to explain to OP how rated mileage works.
     
  11. ultrainstinct

    ultrainstinct Member

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    Thanks everyone, a lot of good replies on here and the other thread. I'll try a few more experiments..

    I think if there was a list created that was ranked in order of what features or method of driving causes the most loss in efficiency to the least, that would be helpful to a lot of people going through the same thing. I would imagine speeds >65mph would be number one, then A/C number two, etc.
     
  12. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    #12 AlanSubie4Life, Sep 28, 2019
    Last edited: Sep 28, 2019
    Speed is big (Wh/mi contributor due to aero goes up with square of velocity). At 65mph it is something like 150Wh/mi due only to aero (the remaining 100+Wh/mi is due to other frictional losses/rolling resistance, etc.)

    So multiply 150Wh/mi*(v^2/65^2). Just an approximate formula. Remember to add the fixed losses to that result though!

    Here is a rough fit including fixed losses and the frictional (constant per mile traveled) losses (plot is of Watts vs speed, not Wh/mi...you have to divide through by velocity to get the Wh/mi...be careful):

    cubic fit calculator - Wolfram|Alpha

    Heat is probably next.
    AC is usually about 3 times less impact than heat (it is not that big a deal in general). However, these go DOWN the faster you go. They are a fixed load; you take the watts and divide by velocity to get Wh/mi.

    None of the other car accessories really matter significantly for consumption. Again - fixed loads divided by the velocity. So for true range they really hardly matter.

    Other things like rain and wind can be significant.

    Elevation costs you about 7-8 rated miles per 1000 feet in an AWD. That is just based on physics; potential energy. Not really a loss in efficiency but something to know. If you go up and down a lot it definitely hurts efficiency since regen is not 100% efficient.
     
  13. KenC

    KenC Active Member

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    You've only driven 1000 miles, your car is barely broken in.

    Your consumption does seem on the high side. According to ABRP the reference consumption, which is conservative, is 267Wh/mi at 65mph, for driving around San Jose. If you bump that up to 75mph, then the reference consumption goes up to 311Wh/mi, so 16% more. You're another 16% above that. Are you driving into a headwind both ways, cause your consumption would be as if you were driving 85mph.

    Why not set your climate on Auto 72, and let the car handle the fan speed. Drive another 1000 miles before coming to any conclusions. Also, check your tires for any unusual wear.
     
  14. SilverSp33d3r

    SilverSp33d3r Member

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    What driving settings do you use? Standard regen and chill mode can significantly help wh/m readings if not on highway. Is this your first ev?
     
  15. ultrainstinct

    ultrainstinct Member

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    Is braking in an EV a thing? I get the tires part, but is there another aspect that needs to be broken into?

    Yes it's my first EV. I use standard regen and chill mode. I haven't kept the fan on auto though, so I'll try that.

    It's probably been asked before, but since heat consumes a lot of energy, is there a path to transfer the heat from the battery pack into the cabin? That would also keep the battery cool as the heat is transferred.

    So the list so far looks like this:
    Factors under the driver's control:
    1. Speed
    2. Heat
    3. A/C

    Factors not under the driver's control:
    1. Elevation
    2. Weather (Rain/Wind)

    Is that correct?

    Also, like I mentioned earlier, is there a way to change the battery icon from rated mileage to expected mileage based on customization chosen on your vehicle (19"/20" rims, aero cover off, etc)? If not I think that would be a really good feature to have so people can more accurately get a sense of how much range they actually have.
     
  16. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Some people have claimed things get better after the bearings and stuff break in. I never noticed any significant efficiency change though. Likely extremely insignificant compared to these other factors.

    Tires do break in a bit supposedly (since they flex more easily they might have slightly less rolling resistance). But again, seems fairly insignificant.

    No. The battery actually typically has to be heated, unless it is extremely hot - even in the summer it will sometimes precondition the pack before arriving at a Supercharger, by generating extra heat (generated by running the motors non-optimally to generate extra heat). Obviously on a really really hot day it does not do this. But under the conditions where you would want to heat the cabin, the battery will also likely need extra heat for optimal Supercharging (otherwise it is usually being heated by any waste heat from the motors, and it is just the temperature it is).

    No. But you can use the Energy Consumption screen (one of the apps) to see range predictions - not particularly accurate though, since there are only 30/15/5 mile interval projections. You use this screen during a trip (use the Trip tab) and it is pretty helpful - takes into account elevation and such after you enter a destination. It takes into account your recent consumption, so can sort of take into account wheel choices, tires, aero covers, etc.
     
  17. TimothyHW3

    TimothyHW3 Member

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    I find the energy bar exceptionally accurate as it factors in elevation and speed on the trip(except for weather and HVAC this will give you a great estimate) I haven't seen a more accurate estimate on an EV,
    let alone gas car. Gas cars will not factor elevation on a coming trip when they make their estimates.

    For the initial estimates under Trip it uses the typical range constant I talked about so if you know it, you can easily calculate your miles if you know your consumption on your trip, roughly.
    Also, while you drive it will give you updates and if you look into Trip it will update the % left very accurate. The offset I have seen in Trip is minimal, barely 1-3% from the current prediction(not initial, this is a rough estimate with constant consumption!) It also enabled you to see battery rated miles AND % at the same time, because under Trip it always shows % left and if you leave your display on "disstance"(aka miles), you have the best of both worlds.

    The energy gauge is the most important thing in the car and I don't know why it is burried within 2 clicks and is not explained in detail while delivery. Tesla should teach their delivery agents only the energy tab and don't bother users with summon or other useless features.

    If they did that, we wouldn't have so many posts about it.
     
  18. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Yes. To clarify my above post (it was not clear) - yes, the Trip page is very helpful and quite accurate. The Consumption page just uses direct calculations using the constant so the utility is pretty limited, as driving conditions (road grade specifically) can change so much.
     
  19. XLR82XS

    XLR82XS D M C

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    How do you figure a crazy hit to efficiency? 19" wheel/tire is larger and as such will have less rotations the higher the vehicle speed.

    Tire Size Calculator
     
  20. kailm

    kailm Member

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    Diameter of tire + wheel is same for all 3 wheel setups. So same rotations. Otherwise speed indicator would be wrong and range estimation. (not that its precise now)
     

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