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The effect of hills on range

Discussion in 'Model S' started by dlmorgan999, Jan 29, 2012.

  1. dlmorgan999

    dlmorgan999 Member

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    I've recently been wondering about something now that I can't seem to get the Model S out of my mind :wink:. For my daily commute I go over a hill. The climb only lasts about one minute but the altitude gain is about 400 feet. On one side of the hill, the slope is probably between 30 and 40 degrees for a brief bit.

    So I have two questions. 1) how will an electric car handle this kind of slope and 2) what is it likely to do to range (I realize this question is probably difficult to answer so guesses are OK :smile:). Maybe the Roadster owners can chime in?
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    This would basically have almost no significant effect on your range. I wouldn't worry about it. How long is your commute? The odds that one small hill would be the difference between you making it to your destination or not are very small.
     
  3. Doug_G

    Doug_G Lead Moderator

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    dsm363 answered the second question.

    As for "how will an electric car handle this slope?", it will (a) rocket up the slope like it's not there, and (b) maintain constant speed on the way back down again, due to regenerative braking. On the way back down you will gain back a big chunk of the energy you spent going up it.
     
  4. bonnie

    bonnie Oil is for sissies.

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    Big +1 on 'rocket up the slope'. I drive up a fairly substantial hill on my commute to the office each morning.

    I can't tell you how many times I've had cars try to show me they're faster .... I let them keep pace for a bit, til I can hear their engine huffing and puffing ... and then I accelerate. Almost as much fun as the motorcycle that stalled out when the light turned green.
     
  5. dlmorgan999

    dlmorgan999 Member

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    Thanks for all the replies! The main thing I was curious about was the max current the drive system is capable of.

    To answer dsm363's question, my commute is pretty short - 12 miles each way and a daily total of between 30 and 35 miles. As I was thinking about the current required to go up a steep hill, I just wondered if it would make a measurable dent (5-10%) in range per charge. Not really worried about it - I'm too excited waiting for my turn in line. :smile:
     
  6. dhrivnak

    dhrivnak Active Member

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    My experience is you will get less than the ideal miles. On the level I can go a mile with about 250 watt-hrs of energy. In my hilly neighborhood I will burn about 300 watt-hrs/mile. So while it is true there will be NO problem in going up a steep slope and it true you will gain miles back going down overall you will burn more power. So if you are getting the 160 mile pack it may only be good for 140 miles in hills.

    And by the way 400' is nothing as I have easily gone up 10X that in some of the big hills around here.
     
  7. dlmorgan999

    dlmorgan999 Member

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    That's what I was thinking - maybe a hit of 10% or so. I'm planning to go for the 230 mile pack. Even though I don't need anywhere near the range, and I plan to charge every night, I like the idea of missing an evening charge here and there with no penalty. Plus I want to be able to travel from Portland to Seattle occasionally. :wink:

    I'll bet. This is a very short hill (less than two miles up and back down).
     
  8. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

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    Have any of the SF Bay Area Roadster owners driven from the South Bay through the Santa Cruz mountains on Hwy 17 to get to SC?! If so, could you please share how the Roadster did on that trip in terms of range falloff up there? I could relate to that and kinda' extrapolate to what I can expect with the Model S.
     
  9. Dragon

    Dragon Lightning Green Fairytale

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    Yesterday I did a 185 km (115 miles) trip with my Roadster. Starting at 600 m above sea level going up to 2200 m above it and down to 1500 m again for the first ~92 km and then the same way back. There was no one on the street and I drove like crazy whenever possible. Started with 294 km (183 miles) ideal range and ended the trip with 74 km (46 miles) of range left. If you do the math, that are only 35 km (22 miles) difference between consumed ideal range and effective driven kilometers.

    I'm going as far as saying that if you drive normally, the loss of hill climbing is negligible.
     
  10. Eberhard

    Eberhard #421 Model S #S32

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    as higher you go up, the less the air resistance will be. that save energy. because you are electric, you will not suffer power loss because of the lower air pressure.
     
  11. AndrewBissell

    AndrewBissell Member

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    #11 AndrewBissell, Jan 30, 2012
    Last edited: Jan 30, 2012
    I think altitude may be playing a part here. Your drive was between 600 and 1500 m (2000 to 5000 feet approx) with therefore lower air pressure and hence less aero drag. If you did the same thing at sea level* then the extra drag would result I higher Wh/mile and a bigger discrepancy between Real and Ideal miles.

    * imagine a sawtooth range of hills each no higher than 50m (160 feet) but stretching for miles of up and down so that in total the distance climbed and descended was the same as Dragon's drive, but it was all within 50m of sea level.
     
  12. NigelM

    NigelM Recovering Member

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    My Roadster's altitude read-out never moves from zero, but after following this forum for almost a year I'd say I get pretty much the exact same performance as everyone else. The only factors that make a significant difference are speed, drafting, regen braking and top on/off. In other words, mostly driving style...

    Much of my driving is stop/go around town and the real range is ridiculously high; but a 110 mile freeway drive that I did on Saturday at *ahem* higher speeds with the roof off used up 195 miles of range (but it sure was fun!:biggrin:).
     
  13. ElSupreme

    ElSupreme Model S 03182

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    Come on the Sunshine Skyway Bridge is got to be what 150ft, and about 140 feet taler than everything else.
     
  14. NigelM

    NigelM Recovering Member

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    See this Roadster thread. BTW, it's a fantastic ride in an open top Roadster. :biggrin:
     
  15. richkae

    richkae VIN587

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    A couple of years ago I drove over Syskiyous pass in Oregon in my Roadster.
    The top of the pass is at 4310 feet and its about 2300 feet up one side and down the other.
    From parsing my Roadster log files, it shows that I consumed 3987 Wh on the way up over 6.9 miles at an average speed of 56mph. ( 577 Wh / mile )
    On the way down it regenerated 721 Wh over 6.6 miles at at an average speed of 54mph - almost 3 ideal miles worth of energy regenerated on the way down. ( -109 Wh/mile )
    The total Wh consumed over the 13.5 miles was 3266 for an average of 242 Wh/mile which is amazingly close to the Wh/mile you would use driving 13.5 miles over flat ground at 55mph.

    I calculated the energy used from each 1 second drive record in the log file ( multiplying volts and amps ). I'm not sure if there is some unaccounted for losses in there ( recharging loss on the regen most likely )
     

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