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Regen gave me some miles back!

Discussion in 'Model S: Driving Dynamics' started by RyanG, Jul 4, 2013.

  1. RyanG

    RyanG Member

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    Took my first trip down to Santa Cruz in the S today. I was hoping to see regen give me some miles back on 17. On the way down there the mileage just stayed the same so I was a little disappointed. However, on the way back I did get some miles back.

    The weird part was that it didn't just increase by one mile at a time, but rather it suddenly jumped up by 3 miles all at once. (I was watching pretty closely.) Just curious what explanations people might have for this sudden jump. What does it tell us about the firmware/battery?
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Mostly it tells us that the display doesn't provide continual output. It updates every so often.
     
  3. WarpedOne

    WarpedOne Supreme Premier

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    And even then it provides too much detail.
    When full it says it has 265 "real" miles left ... what is certain is that you wont get 265 miles out of it, probably less, maybe a bit more.
    Much more honest estimate of remaining range would be displayed in about 1/20 of "max real range" . i.e. 13 or maybe 10 mile steps. It would fluctuate much less, cause much less confusion and end up being correct much more often.
    As it is, the car presents accuracy that just isn't there. Oh, I still have 17 miles left.. should be no problem to travel those 15 miles ... stranded every second time.
     
  4. wycolo

    wycolo Active Member

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    Jumping up 3 or 4 miles at a time is easier to recognize ergonomically. Staying at the same miles is still a 'free ride' yet with complete (seamless) speed control using regen. This car is unsurpassed in the mountains for ease of use. In a class by itself, it would appear. Perfection never gets old. I drive in awe.
    --
     
  5. deonb

    deonb Active Member

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    I've noticed the jump is directly related to the kWh regained. Going down a long mountain it will "tick" back up 3 or 4 miles at every 1 kWh gained.

    This seems to be a smoothing effect so that a few watt-hours gained from minor hills don't cause the display to oscillate between 2 numbers.
     
  6. RyanG

    RyanG Member

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    These replies basically touched on my a couple of my views of this. I'm mostly curious if this is purely a software smoothing to avoid jumping between numbers (as deonb posited) or if it's some measurement accuracy/precision issue or even loss of accuracy in the software (or could be some combination of of these). If it's built-in smoothing then why jump 3 miles, not just 2? Or is the software internally at some level using kWh as integer units whereas hardware-wise it could measure in fractions of kWh? Given 265/85 is about 3, it possibly is this, but how does it tick down 1mi at a time then? As WarpedOne said, maybe it just tries to present too precise of a number on the way down even though it doesn't really have that information (it just estimates based upon tracking current output). So is there some low accuracy capacity measurement + an estimate based upon some some other (non-capacity) measurement. I guess this would be my theory and that the additional estimate based upon some non-capacity measurement possibly does not account for regen.
     
  7. rdalcanto

    rdalcanto Member

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    I noticed the same thing. Recently went up to the Brighton Ski Resort in Salt Lake City. When driving back down (14 miles, almost 4,000 ft), I gained around 9 miles of range back. Never used the brakes. I felt superior to all the ICE drivers around me who were using fuel driving down AND wearing out their brakes.... :)
     

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