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Model 3 efficiency, one data point

Discussion in 'Model 3' started by Austindude, May 25, 2018.

  1. Austindude

    Austindude Member

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    Just one data point but I thought I'd try an experiment. I have the 18 inch tires with the aero hub caps removed.

    I initialized charging using a gen 1 mobile unit on my 240 V 50 amp breaker circuit.

    The Model 3 display read as follows:
    76% battery remaining (237 miles), 40 amps, 241VAC, so initial calculated power being delivered is 9.64 kW

    Stopped charging after exactly one hour and the actual energy delivered from my house meter was 9.35 kWh
    The model 3 display now reads:
    88% battery remaining (274 miles)

    I then drove the car in town and highway over a two day period (more than 48 hours) 32.2 miles.
    The model 3 display now reads:
    77% battery remaining (237 miles) for 32.2 miles and 222 Wh/mile (this is an average)

    To be a little more accurate I should have driven the car until the display showed 76% or 237 miles but there are many other inaccuracies in this experiment anyway.

    During the one hour charge time I (remotely) monitored the actual power usage at my house meter.
    The vampire drain of my house (air conditioner off but refrigerator may have cycled, TV vampire drain, etc) is included. The trip milage shown is over two days and includes both highway and around town usage.
    90 degree Texas weather, 74 degree cabin during drives. Model 3 vampire drain for more than 48 hours is included.
    Energy used by car over more than 48 hours and 32.2 miles is (32.2miles x 222 Wh/mile)= 7.148 kWh (7kWh display) Energy delivered to the car was 9.35 kWh
    Actual watt hours per mile including car vampire drain for two days is: 290 Wh/mile or 3.34 miles/kWh
     
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  2. Austindude

    Austindude Member

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    Sorry the display reads 77% 239 miles remaining not 237 miles.
     
  3. Brando

    Brando Active Member

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    damn those vampires
    try plugging up the drain
    drive more, lowering the denominator, decreases the vampire feeding, right?
    ps- charge at night when house vampires are napping
     
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  4. Zaxxon

    Zaxxon Supporting Member

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    Here's a quick example of driving efficiency. I took a trip from Denver to Colorado Springs tonight, which for those not familiar is a pretty straight shot down I-25 with a speed limit of 75 mph most of the way. It's, shall we say, not the most efficient route. This route in my old Leaf (EPA range 107 miles) would result in me going 15 mph under the limit or stranded on the side of the road ten miles out despite the trip only being ~70 miles.

    Check this out...

    424340989.png

    Screenshot_20180525-210307.png

    Screenshot_20180525-210321.png

    99.8% ratio of real to rated efficiency. Craziness.
     
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  5. SageBrush

    SageBrush 2018: Drain the Sewer

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    Interp: you can drive ~ 10 mph faster than the low-landers and see similar efficiency ;-)
     
  6. Zaxxon

    Zaxxon Supporting Member

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    It's nice when altitude doesn't come with an engine efficiency penalty.
     
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  7. dhrivnak

    dhrivnak Active Member

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    #7 dhrivnak, May 30, 2018
    Last edited: May 30, 2018
    5E92A493-1CBD-4EED-A637-1CA23228EDC8.jpeg Here is a second data point on the excellent efficiency of the Model 3. We are nearing the end of a 2000 mile trip around the southeast and have averaged just under 230 watt/mile and most of the trip has been interstate running close to the speed limit 60-70 depending on section. Normally we were at rated miles or even more. For example this last leg we left with a full charge 312 miles and 121 miles in we still had a range of 200 miles. We were using the AC as temps are a humid 85. While I wanted to go farther the bladder was the weak link. Elevation is about 400’ and fairly level.
     
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  8. Brando

    Brando Active Member

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    higher altitude - less aerodynamic drag, right? in theory anyway - Denver (mile high city) compared to say Florida?
    One of our math/physics people might try to calculate. might be that tire/pressure make as big a difference?
     
  9. Zaxxon

    Zaxxon Supporting Member

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    For an EV, yes. For an ICE vehicle, it also means less airflow and therefore less power per stroke. 3% loss per 1,000 feet gained is what I've read. Higher altitudes also have lower octane minimum requirements. (Here in Denver, for example, 'regular' gasoline is 85 octane vs 87 in most of the US.)
     
  10. SageBrush

    SageBrush 2018: Drain the Sewer

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    Density of air - Wikipedia

    Note that air pressure is affected by both density and temperature, in opposite directions.
    So e.g going straight up 2000 meters results in about 20% less density and about a 5% temperature drop
    The sum effect is about a 15% reduction in air drag
     
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  11. AWDtsla

    AWDtsla Active Member

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    Hmm that would indicate the car is using 220Wh per rated mile? Or perhaps the correction factor in Teslafi is wrong. Lower than anything I guessed. That put a 75kWh pack at 75/.220 = 341 miles.
     
  12. Zaxxon

    Zaxxon Supporting Member

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    Yes, 220 rated.
     
  13. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    My wife recently want on vacation to Boise, ID and on one day sent a text asking me what I'd think of retiring to Idaho.

    I hadn't thought of the efficiency benefits. I guess that's a check in the plus column. It'd help make our future autonomous electric taxi/rental services cheaper.

    (I currently live about 120 feet above sea level somewhere colder).
     
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  14. SageBrush

    SageBrush 2018: Drain the Sewer

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    I didn't notice before but your data is another example of the efficiency numbers not matching up with EPA reported battery capacity.

    68 miles * 220 Wh/mile = 14.96 kWh
    App reported kWh use: 15.14 kWh
    App reported % of battery used: 23%

    15/0.23 = 65 kWh full battery capacity
     
  15. Zaxxon

    Zaxxon Supporting Member

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    The Denver guys who just set the hypermiling record at 606 miles got 66 kWh out before their car shut down.
     

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