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Newbie battery / range question

Discussion in 'Model S: Battery & Charging' started by adambirozy, Aug 7, 2017.

  1. adambirozy

    adambirozy Member

    Joined:
    Jun 14, 2017
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    Location:
    fullerton, CA
    Hello

    I have a new 2017 MS 75 I have had for about 2 months now. I tried to keep track of the range for each charge as I mainly do the same commute every day: 37 miles each way for a total of 77 miles. In the morning, I average about 75mph and going home I average about 30 (rush hour). It has been around 90 degrees here, so I keep the air on. I try not to mash the accelerator and drive pretty normal.

    During that time, my 90% would read at about 260, and after one round trip of 77.7 miles, my estimated range would be around 155. Does that seem correct? It is almost double the miles of range gone than actual miles traveled.

    Any advice would be appreciated.
     
    • Funny x 1
  2. fasteddie7

    fasteddie7 Member

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    uniontown PA
    Check your Wh/mile. It's in the energy setting. It's usually somewhere between 200 and 400. There's 1000 watt hours in a kilowatt. So if that number was 250 wh/mi then you'd get about 4 miles per kw. Check this against what is actually used and you might see the loss not come from driving, but drain from when you're not (smart conditioning, cabin overheat protection, etc.)
     
  3. kort677

    kort677 Active Member

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    florida.
    slow down! at 75 MPH you're going to see a 20% diminishing of the rated range, by slowing to 70 MPH that would be about 10% loss. to put it in terms I use, try to keep the wh/miles under 330 for the best mix of speed and range. that said, if you know that you trip is the same 77 miles and you recharge every night speed away because the range really won't be a factor.
     
  4. TexasEV

    TexasEV Well-Known Member

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    You used about 105 miles rated range to travel 78 miles, so its 34% more, not almost double. A little more than I would expect for driving 75 mph, but not much more. You say it's round trip so some of that will be a few miles lost during the day from vampire drain, maybe more than a few at 90 degrees. Remember rated range is the range on the EPA test cycle, not 75 mph driving. Energy use goes up exponentially with speed.
     
    • Informative x 1
  5. tnt1971

    tnt1971 Member

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    There is a magic wh/mile number that gives you your rated range. For my 85D, it is 290 and you can tell this because at that number the estimated range will equal the rated range.

    I am a pretty conservative driver. I hit it every once in a while but I generally drive 60-65 on the highway and don't rapidly accelerate/decelerate. For short trips, I find I lose 5-10 miles per day, much more than the "vampire drain". I don't use the pre-condition with AC as well. The numbers just never seem to add up. I think the car uses a significant amount of energy shutting down and restarting. For example, on a weekend where I drive 150 miles of 15-20 mile trips I would have to get 250 wh/mile or less to have my loss in rated range to equal what I actually travel.
     
  6. Rocky_H

    Rocky_H Active Member

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    @adambirozy , This is the answer. The rated miles number on the display is based on the consumption rate from the EPA testing procedure. Driving at 75 mph is faster than that testing procedure, thus is uses up the "rated miles" faster than a 1 to 1 ratio. That's all there is to this.
    I know you're new, but it doesn't help to incorrectly say it's using up the miles at "double" the rate when it's only thirty-some percent more. You'll get that kind of overuse from speeding or extra heating use in the winter.
     
  7. Boatguy

    Boatguy Member

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    SF Bay Area
    @adambirozy , first check that in the units settings that you have the display set to "rated" miles and not "Ideal". When my S90D was new the 90% charge was 264 so it's suspicious that an S75 would be 260.

    Then, you can use the trip meter and dashboard display to understand how fast you should expect to lose rated miles. When you leave in the morning, note the rated miles on the dash and reset Trip A. When you arrive at work, note the power used (kWh) and the change in rated miles. Divide the power by the miles and you'll know the rate at which your car loses rated miles. That's rated miles, not miles driven.

    Trip A will also show your Wh/mi actually consumed, and as someone else said, it will be in the range of 200-400 Wh/mi. That's the amount of power you're using per mile driven which varies with speed, driving style, terrain, etc. The ratio of those two will tell you how fast you'll consume rated miles.

    For example, if you are consuming 310Wh/mi and losing a rated mile ever 275Wh, then 310 / 275 = 1.13 which means you'll use 1.13 rated miles for every mile you drive.

    PS: Drive as fast as you want! The MS is nothing if not fun to drive! ;)
     
  8. fasteddie7

    fasteddie7 Member

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    I agree my MS 75 is 258 at 100% and 229 at 90%
     
  9. fEVer

    fEVer Member

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    Los angeles

    That might be part of your problem right here.
    :)
     
  10. henderrj

    henderrj Member

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    Graham, WA, United States
    I think the best thing to do is to ignore it! Just drive the car and have fun. It's not like you're running low on Miles here.
     

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