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Putting some numbers on the factors that affect range

Discussion in 'Model S: Battery & Charging' started by ChadS, Jan 27, 2013.

  1. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    One direction batteries to potential energy should probably be closer to a 10% loss; a round trip battery to kinetic/potential back to battery or grid to battery to kinetic/potential is more like 20% loss. Anyway, 10-20% of 6 miles/1,000 feet pushes the number to about 7.

    I find that if I use GPS altitude from my iPhone and watch as I go up and down mountains, the 6-7 miles per 1,000 feet tracks within a couple of miles on big ups and downs. My Pagosa to Boulder drive crosses the continental divide three times, Wolf Creek, Fremont, and the Eisenhower Tunnel, with Poncha Pass thrown in for good measure. I do that drive or the other way, once or twice a month and it gives me lots of chances to do the mental math as I drive. :wink:
     
  2. moseson

    moseson New Member

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    Your math appears spot on, making me feel there's nothing wrong with my car. I drove from northern nj down to the south shore. Starting with 265 miles, I traveled 190 miles and had just 9 miles left. I wish I had read your post first, b/c I was worried the whole way down as my wide margin rapidly disappeared. Don't know about you all, but this math is quite disturbing, especially since there are no rapid chargers where I was traveling. My tesla was out of commission, charging for my trip back my whole time down at the shore
     
  3. deonb

    deonb Supporting Member

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    So I followed the "If you are ever in trouble, slow down" advise but realized after a while there is a bit of an issue with doing so blindly.


    I was driving from Grants Pass to Eureka, and tried to conserve power by driving slowly. Part of the road is anyway slow (Redwoods), but for the rest I tried to stay at 50. But no matter how I drove I couldn't get the usage to drop below 400 wh/mi. When I eventually sped up to 60 the usage immediately fell to 360 wh/mi.

    I believe the reason is that at the slower speed you spend proportionally more power to power the HVAC and heating the battery (it was 31 outside) than the power that you require to drive faster.

    Does anybody else have a similar experience?
     
  4. ChadS

    ChadS Petroleum is for sissies

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    If HVAC is on full blast, from the numbers I would expect ~45mph to be the most efficient speed - you'd use MORE power if you go slower than that. The curve down there is pretty shallow with 100% HVAC, so 50mph wouldn't look very different. See chart HERE.

    The less HVAC you have, the deeper the curve and the further back it goes - with no HVAC (by which I mean moderate temps, since the car uses HVAC in cold weather even if you turn the cabin controls off), ~18mph should be the most efficient speed.

    However, this is just going by the numbers. I haven't tried it in real life and compared wh/mi rates.
     
  5. dgr

    dgr New Member

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    Plug In America Survey on batteries - Are You In?

    New to this web talk stuff but was one of the first reservations for the Tesla Model S Reservation Confirmed 5/16/09.

    This is part of an eMail that I received from Tom Saxton. Tom and his wife Cathy put up the Tesla Owner Map back in 2007. http://www.idleloop.com/tesla/index.php They are no longer continuing support of this site.

    Plug In America also has a survey for the Leaf and RAV4-EV.

    Tom's message below
    "Instead of adding to our old map, I would like to encourage you and other Tesla owners to participate in the surveys I am now conducting via Plug In America. The data being collected by these surveys will have much more value to the owner community. Like our owner map, these surveys keep your personal contact information private. Unlike our owner map, the surveys allow full access to the data(except your name, email, and VIN number) so anyone can view, analyze, or integrate the data into other projects.
    The Plug In America Tesla Roadster survey:
    http://www.pluginamerica.org/surveys/batteries/tesla-roadster/survey.php
    The Plug In America Tesla Model S survey:
    http://www.pluginamerica.org/surveys/batteries/model-s/survey.php
    A full overview of the surveys being conducted and results from related studies is here:
    http://www.pluginamerica.org/surveys/batteries/
    Thanks for participating!
    --
    Tom Saxton"

    What do you think and are you going to post your information. It seems like the leaf and rav4 people are out numbering the Tesla owners.
     
  6. neroden

    neroden Happy Model S Owner

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    I wish I could put proper numbers on it, but snow caked in the wheel wells is the single most significant reducer of range I've seen, driving my mileage up above 500 wh/mi consistently and above 600 wh/mi sometimes. It seems to be a first-order effect, dominant over all other effects on mileage.
     
  7. EchoDelta

    EchoDelta Member

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    Maybe a wheel well defroster for the subzero package would be in order if that is the case?
    Googled and some dude has patented the idea (eye roll): Patent US20080083719 - Fender well deicer (defroster) - Google Patents
     
  8. kcveins

    kcveins delivery 2/7

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    Major issues here in Chicago with the recent cold snap. On Monday, I left the garage with a good battery charge (rated 220 miles). Drove 20 miles in -15F weather, parked at one place, 1 hour later went to another office (12 miles), stayed there for 4 hours; came back to the first office for 6 hours and drove home. Total distance driven 65 miles, outdoor temp stayed more or less constant at -15F, partial snow packed roads, drove <40 mph, interior temp 68F (needed this to get the windows defrosted), butt warmer on low and ended up with 40 miles left. Now today, with 28F and good roads, lost only 5 rated miles more than distance driven.
     
  9. ChadS

    ChadS Petroleum is for sissies

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    Thanks for the numbers. Something similar happened to me last winter (not as bad because it wasn't as cold here) and it can be disconcerting. The initial heating of the battery and cabin takes a LOT of power, so taking several short trips and letting the car cool down in between does terrible things to your wh/mi. But fortunately, if you have short enough legs and long enough stops that this is a big issue, your day's driving is typically in the 65-mile range rather than the 265-mile range.

    Things (fortunately!) look quite different when you take a single trip.
     
  10. neroden

    neroden Happy Model S Owner

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    Nice idea. I don't need it where I live (the roads get plowed really fast) but in Michigan it would have been a godsend.
     
  11. greencharge

    greencharge Member

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    The omnipresent Chargepoint J stations did no more than 14miles per hr charging this snow season
     
  12. slipdrive

    slipdrive Member

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    Perhaps Version 6.0 will have some account of these factors in the Nav ? Especially between SC's.
    Since majority of folks will just look at average miles, there could be some unfortunate and misplaced reliance on indicated range versus reality. Missing reality could really suck.
     
  13. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Wind is a 4-Letter Word - Well at least when it's a headwind...:eek:

    I originally posted this at Supercharger - Buckeye, AZ - Page 10 after rsanchez commented on almost running out of energy due to a headwind from Holbrook to Flagstaff, AZ. Monsoon made a recommendation that I post this where others might see it better, so here it is.

    Weather Underground reports data from an amazing number of personal weather stations and presents it on their WunderMap. For example, near Flagstaff: WunderMap | Interactive Weather Map and Radar | Weather Underground

    The best way to get to this is to open www.wunderground.com | Weather Underground, search for your city of interest, then open the WunderMap link on the lower right. You may have to play with parameters to get a view like mine below, but it is great info. Remember the little pointer is like the tail of an arrow, pointed from where the wind is coming; if it's pointed the way you are going, it's a headwind; if it's pointed the way you are leaving its a tailwind. In the picture below, there is a gentle head wind reported in Winslow if you are driving West. Little barbs are 5 kts of wind (like the one SE of Flagstaff below), big barbs are 10 kts each and flags are 50 kts each, all standard weather map stuff. If I am hypermiling somewhere, I will pull this up on the MS web browser to see what's ahead.

    View attachment 43770
     
  14. jerry33

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

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    I use Weather Underground all the time. However, I use the Classic view.
     
  15. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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  16. jerry33

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

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  17. wycolo

    wycolo Active Member

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    Lacking windsocks, flags or plastic shopping bags hooked on fences for visual indicators of headwinds, I look to keep the orange power usage line at or as near as possible to the FIRST MARKER. Then I know I'm not over-doing it. This can limit speed to 45 mph across the uphill 'flats' in the case of 30 to 45 mph westerlies. When you reach the mountain grade going up a drainage this wind dies down considerably.
    --
     
  18. David99

    David99 Active Member

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    Reading your post I was getting excited about the 'pizza pan' wheels. I tried to find some real world references on how much range it would actually gain. You put it 10% which seems rather high. I found this guy doing a before and after test and the difference was 3%.
    Weather Spotters wheel cover how to - EcoModder

    I guess the difference also depends a little on the driving speed and is more noticeable when going faster. But 3% isn't worth enough spending a lot of money on closed wheels or do some sort of mod.
     
  19. ChadS

    ChadS Petroleum is for sissies

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    Chgd Up on these forums says he got 6.5% of his Tesla HERE. I mostly put that in as a joke/example, but must have misremembered the amount. I will fix the number in the original post and link to the source.
     
  20. hiroshiy

    hiroshiy Supporting Member

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    Wow 6.5% is impressive if true!
     

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