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The effect of passing on range....

Discussion in 'Model S: Battery & Charging' started by Mayhemm, Aug 30, 2013.

  1. Mayhemm

    Mayhemm Model S P85+ "Lola"

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    I plan to travel a lot in my Model S when it arrives (the first summer already has nearly 10,000km earmarked :love:) and much of that will be highway travel. Perhaps I'm simply impatient, but I cannot stand traveling in convoys (many cars following close behind a slow-moving one to form a tightly-packed, slow-moving line). If presented with the opportunity to pass/overtake someone safely, I usually take it. I expect this will be quite easy in a vehicle as powerful as Model S. Unfortunately, I expect each passing effort will have quite a negative effect on my overall range.

    Math fanatics rejoice! I would like to estimate just how much detriment I do to my range each time I pass a vehicle (or even cumulatively over a 100-mile section). In a P85 Model S, 10 seconds at full power should be all that's required for a single-vehicle overtake, followed by 5-10 seconds of regen at 30-50% capacity. On a long trip with heavy traffic, I can see myself passing someone at least once every five miles. Work in the occasional multi-vehicle overtake (say 20-30 seconds at full power, followed by appropriate regen).

    The broad factors affecting range (temperature, speed, weather, etc) have been discussed in other threads, but I don't recall any discussion of specific-use effects such as overtaking. If I am mistaken, please direct me to the appropriate thread. Thanks.
     
  2. evme

    evme Member

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    #2 evme, Aug 30, 2013
    Last edited: Aug 30, 2013
    I don't know about exact specifics, but dragtimes tested the Model S for drag racing and they found that from 0 to slightly over 110mph consumed 1.1kwh. Then they were able to regen 0.6kwh. That said, your not exactly starting at 0 or regening to 0.

    You will probably use up around the same 0.5kwh every time for single vehicle (Assuming 10 seconds speed up and 20 seconds of regen). Why would you regen for only 5-10 seconds though?
     
  3. Raffy.Roma

    Raffy.Roma Active Member

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    @Mayhemm

    If your trips will be widely within the allowed range of your Model S I think you shouldn't worry of consuming a little bit more energy to overtake other cars.
     
  4. fiksegts

    fiksegts Active Member

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    10 seconds at full power is way too long to pass another car, you're in a P85 not a Prius.. :)
     
  5. RKM

    RKM Member

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    Yep, agree with this. 10 seconds of full power acceleration from say, 90 kmh and you'll likely be "pinning the needle". Assuming there were a needle to pin that is. I can't give you accurate numbers, but would estimate that even in an S85, I can very quickly overtake vehicles at highway speed in well under 5 seconds using perhaps 300kw. If you were to do this every five miles over a 100 mile distance, as you suggest, the math looks like this... 280kw X 5 seconds X 20 per 100 mile distance/ 3600 seconds per hour = 7.8 kwh consumed. The 280kw is the difference between the 300kw passing power and the 20kw used to maintain highway speed. Discounting regen, passing regularly and vigorously may cost 10% of your range. Regen might get a couple of those kWh back for you, so a net increase in consumption of 6 kWh (?). This is about 8% range reduction and would cost about 48 cents (at MB hydro rates). Not sure if these theoretical/assumed figures will work out in real life. If so, its pretty cheap both from a range reduction and actual cost to drive in a "spirited" fashion.

    I drive pretty conservatively and will only occasionally open it up to pass someone, so I can't say how well the math holds up. It does seem too good to be true though! Just remember that any Tesla will get to ticketable speeds very quickly. I speak from experience. At least photo radar doesn't affect the license.
     
  6. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Hear, hear!

    I drive a lot of 2-lane mountain roads in Colorado with 65 MPH speed limits and short passing zones. I can be behind a 45 MPH truck, see a short, clear passing zone, and in a few seconds of max acceleration in a P85 be at 90. The MS is so so quiet, that it is shocking how quickly and with so few noise queues, that you hit amazing speeds. I now make a very strong effort to keep the max acceleration periods short to limit my passing speed to 75-80 in a 65 zone. Faster than that just draws too much attention.

    As to battery use, I do a few of these in a 100 mile trip. As long as I recover with regen, and not with brakes, I don't notice any strong effect on range.
     
  7. Zextraterrestrial

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    That's what I was thinking. And 20-30s? How fast do you drive:)
     
  8. Crispix

    Crispix Member

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    You won't even need close to full power to pass someone. Just a light push on the go pedal is enough to quickly whoosh past. And it's fun. I'm finding that energy efficiency is improving with experience and is not impacting the fun factor. It's an entirely different kind of flying, altogether.
     
  9. dirkhh

    dirkhh Middle-aged Member

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    Let's add some data to the conversation. I love the fact that we can do that with a Tesla.
    Now sadly I don't have a P85 so I don't have the data to offer that you are exactly looking for, but maybe this helps anyway. This is from a recent drive with my S60. I was passing very aggressively, let's assume for this post that I was driving somewhere with a speed limit of 100mph... :redface:
    The first graph shows the complete passing in context, the second one zooms in on just the accel / regen part (back to the original speed - it turns out I slowed down even more than that if you look closely).
    So I spent 558Wh to pass (but bear in mind that I would have also spent some energy to maintain speed) and recovered 322Wh in regen. So I used 236Wh to pass - and I'm estimating that it would have taken me about 168Wh to just keep my speed (this is simply by using the 28 seconds prior to passing as benchmark). So total cost of a very spirited passing maneuver? About 68Wh. Or 3/4 of a cent at my electricity cost :)
    Again, all this is with an S60. The P85 can use quite a bit more power (but then would only need to use it for a shorter period of time, right?) - my guess is the number for a P85 would be very comparable. If a P85 driver who is using teslams into a mongoDB to track their telemetry data is willing to do the comparable graphs I'd love to help (this analysis hasn't landed in Hans' github repository just yet... I wrote the code a minute ago in order to be able to respond here... thanks for giving me an idea what else we could do with these graphs :)
    Passing1.png
    Passing2.png
     
  10. dirkhh

    dirkhh Middle-aged Member

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    Oh, I just realized that I technically didn't answer the actual question. Oops.
    68Wh should be about 1/4 mile in range (maybe a little less, depending on other factors)
     
  11. Alpha

    Alpha Member

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    Speed limit of 100mph LOL - love it!
    I will try and show you a similar graph on my P85 soon...
     
  12. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Love the way you put it, and your graphs, dirkh. I believe you're correct about the low ammount of extra energy used to pass and that it'd be similar in a P85. In another thread someone (can't remember who) had a comment about top speed where he said something like "I heard my brother's friend's cousin's pet groomer drove 133 mph on he freeway" :)
     
  13. brianman

    brianman Burrito Founder

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    #13 brianman, Aug 31, 2013
    Last edited by a moderator: Mar 13, 2016
     
  14. dirkhh

    dirkhh Middle-aged Member

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    #14 dirkhh, Aug 31, 2013
    Last edited by a moderator: Mar 13, 2016
    Who took the video while you were driving, @brianman?
    :p
     
  15. yobigd20

    yobigd20 Well-Known Member

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    I drive pretty aggressively 200 miles RT daily. 100 miles each way. I charge to 80% daily which starts me out at around 204-206 miles. When I reach my destination (100 miles), I have between 70-85 miles remaining. (then I recharge back to 80%). So I use about 120-135 miles "range" to go 100 miles. (or for the whole round trip, about 240-270 range to go 200 miles. I overtake at high speeds it feels like every other mile, with cruise control usually at 85. Driving like this is about 20-35% inefficient compared to "normal drivers" IMO.
     
  16. brianman

    brianman Burrito Founder

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    Heh. My car has carbon fiber, not obeche.
     
  17. Mayhemm

    Mayhemm Model S P85+ "Lola"

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    #17 Mayhemm, Aug 31, 2013
    Last edited: Aug 31, 2013
    Yes. It was very late when I made that post. Upon reflection, I realized how ridiculous an estimate it was (my current vehicle can overtake in less than half that time). redface.gif Wouldn't need full power, either. A 10 to 20% boost would probably be sufficient. I suppose when estimating energy usage it's better to guess too much rather than too little?

    See above. And, in my defense, that estimate was for overtaking multiple vehicles at once. Probably hit the speed limiter on a P85 given that amount of time, though.

    Lose 1 mile of range for every 4 vehicles overtaken? Seems a fair cost for having a psychological distaste for traveling in a convoy.
     
  18. Alpha

    Alpha Member

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    #18 Alpha, Sep 1, 2013
    Last edited: Sep 1, 2013
    Using Dirk's code, Here's what 10 seconds @ (nearly) full power looks like in a P85 - whatever you were passing is completely gone in the rear view mirror in less than 30 sec. This is *not* an energy saving move, but rather fun...

    p85pass.png

    (Simulated pass move on the track of course ;)
     

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  19. dirkhh

    dirkhh Middle-aged Member

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    Remind me again where you live? You're starting out at about 85 and end up at about 90, with a quick visit to 113 in between...
    But you didn't show the new summary at the bottom of the graph - that's what I added to answer this question (and Hans has pushed it by now). :)
     
  20. Alpha

    Alpha Member

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    Yes, I revised the post... I'm showing the energy now. I live in germany, right near the autobahn.

     

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