TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Battery Rated Range display not accurate

Discussion in 'Model S: Battery & Charging' started by ladhanikarim, May 11, 2015.

  1. ladhanikarim

    ladhanikarim Member

    Joined:
    Mar 30, 2015
    Messages:
    8
    Location:
    Miami, FL
    Hey Guys,

    I have an 85d that I've had for about a month and recently took multiple trips from Miami to Orlando, I did a full charge that stated I had 270 rated miles avail. I was checking and monitoring my usage and I noticed after driving around 100miles per the trip data, the rated range dropped to 145 instead of 170. I was driving around 70/75 mph and using cruise control. I realize using cruise control is a constant drain and also going 70/75 mph can have an impact on rated range however 25 miles in an hr seems high. As much as I love my car, it's little disappointing to see the rated range is far from accurate on a car that costs around 100k.

    It makes it little difficult to plan a road trip properly when the rated range being displayed isn't accurate. Is this normal or should I have my car checked out by Tesla service?


    - Karim
     
  2. dbullard

    dbullard Member

    Joined:
    Jul 31, 2012
    Messages:
    160
    70-75 will definitely sap your range - that sounds about right. The slower you go, the better your range.

    Cruise control helps, but drag goes up the square of the velocity. The mileage figure is an estimate, based on "average" speeds. I'll guess 60 MPH. Going 75 creates 33% more drag (square law) - and power goes up 53%.

    Check out EV Trip Planner - you can play around with the "speed multiplier" and see how it affects your range. It'll give you an idea if your numbers are good.
     
  3. JohnQ

    JohnQ Active Member

    Joined:
    Jan 1, 2012
    Messages:
    1,585
    Location:
    Redding, CT
    The rated range display can't predict how you're going to drive, the topology or the weather. It's based on a controlled standard in much the same way mpg is on an ICE. 125 miles of rated range to go 100 miles is a 25% increase. That's a bit high, even for 70-75mph, given the flat Florida terrain but I don't know whether there was a headwind or what your A/C usage was. I'll average about 310-320 Wh/mi at those speeds in 65 degree weather with minimal use of A/C. That's about a 15% greater use of energy than used to calculate rated range. Quite literally, YMMV.
     
  4. Racerx22b

    Racerx22b Member

    Joined:
    Nov 17, 2014
    Messages:
    217
    Location:
    West Palm Beach, FL
    What avg Wh/mi is used to determine rated range?
     
  5. JohnQ

    JohnQ Active Member

    Joined:
    Jan 1, 2012
    Messages:
    1,585
    Location:
    Redding, CT
    I don't think anyone has a definitive answer but it's approximately 280-285 Wh/mi.
     
  6. David99

    David99 Active Member

    Joined:
    Jan 31, 2014
    Messages:
    2,048
    Location:
    Brea, Orange County
    The energy graph shows 'rated range' exactly at 300 Wh/mile If you drive at 300 Wh/mile the energy graph will give you an identical number of 'projected range' as the 'rated range'. It is based on the EPA test cycle. What makes this number appear off is that this test was done from a 100% charge to the point where the car shuts down which is somewhat passed the zero-mile point. So when the car shows zero miles, it will still go for a little more depending on the conditions.
    In reality you never want to go all the way to zero and definitely not passed it.
     
  7. SabrToothSqrl

    SabrToothSqrl Active Member

    Joined:
    Dec 5, 2014
    Messages:
    1,518
    Location:
    PA
    it's normal, and you'll get used to it. When I bought mine I was concerned about this as well. Give it a month, and words like Rated Range, Projected Range, Ideal Range, Watt Hours, and all will sink in :)

    At least in FL, you aren't freezing. In PA, I lose a TON of range to the cold... But my daily commute is all of 35 miles, and since other cars also occupy the roads, I can't just peg the GO pedal the whole time... so I usually make it those 35 miles with about 190 to spare...

    Rated Range is kind of a best case scenario (and ideal is just nonsense). basically, turn off the HVAC and heated seats, roll up the windows, and set the cruise at 55 kind of scenario. But that's no freaking fun... also in FL you seem to have super chargers all over the place... I've never charged at one in PA. Go plug into one, use the rest room, and by the time you get back, you'll have another 40 miles in the 'tank' :)

    After 3 months of ownership, I don't even think I needed the 85 battery any more... 95% of the time the 60 may have been fine... but I'm still glad I did an 85 ;)

    However, I also bought like a month before the 70D was announced... which may have swayed me... but no worries, I'm still looking to buy an X.
     
  8. NuclearPowered

    Joined:
    May 17, 2012
    Messages:
    488
    Location:
    USA
    Its 300 wh/mi. In my experience driving at 65mph on flat dry pavement with minimal wind will achieve rated range.
     
  9. TexasEV

    TexasEV Active Member

    Joined:
    Jun 5, 2013
    Messages:
    3,762
    Location:
    Austin, TX
    If you drive an ICE car at 75 mph you won't get the EPA rated gas mileage either. Speed affects ICE cars the same way, but we don't notice change in gasoline consumption as we do battery charge. When driving at 70-75 mph I plan on using 120-130 miles of rated range to travel 100 miles.
     
  10. Rocky_H

    Rocky_H Member

    Joined:
    Feb 19, 2015
    Messages:
    880
    Location:
    Boise, ID
    I think some people at the TeslaMotors.com forum had calculated it to be around 294 wh/mile for the rated miles, but 300 is about right. The other thing you can do to show you an actual estimate based on your actual driving is to use the energy app in the touch screen. It will show you what your wh/mile consumption rate is for your actual driving over the last 5, 15, or 30 miles. On the right side of the display, it will show an estimated number of actual miles of distance you can go, based on that rate of consumption. (Make sure it's using "Average", not "Instant" or else it will jump around too often based on what you're doing right at that moment).
     
  11. commasign

    commasign Active Member

    Joined:
    Aug 31, 2013
    Messages:
    1,058
    Location:
    Davis, CA
    Not sure what the surprise is. Gas cars exhibit the same behavior when they advertise MPG and total range for a full tank. It's always based on EPA test conditions which everyone knows doesn't always reflect reality.
     
  12. SabrToothSqrl

    SabrToothSqrl Active Member

    Joined:
    Dec 5, 2014
    Messages:
    1,518
    Location:
    PA

    I think it's visibility. on most gas cars people shrug off 1-2 MPG because they figure the EPA works as well as any other government agency.
    Since MPG is a poor vehicle comparison, 1-2 doesn't sound like much.

    We should be using Fuel/100 miles. (or km to be even more specific).
     
  13. mspohr

    mspohr Active Member

    Joined:
    Jul 27, 2014
    Messages:
    1,786
    Location:
    California
    The range shown on the speedo is the EPA cycle range and that will rarely correspond to the real world (can be much more or less depending on topography, temperature, speed, etc.). Some people switch this over to display % instead of miles which is probably better.
    If you want to get a more accurate range on a trip, pull down the Energy Monitor/ Trip Monitor screen (center top icon). This will show you a much more accurate prediction of your range which does take topography, speed and temperature into account. It is updated continuously so you can easily see the effect of changes in speed on your range. I always have this graph up when I'm doing long distance trips. If you see the graph going into red, you can slow down and watch the graph recover (speed is the largest determinant of range unless you are in the mountains).
    You can also use EVtripplanner ahead of time. It is excellent and also takes topography, temp, etc. into account.
     
  14. Cottonwood

    Cottonwood Roadster#433, Model S#S37

    Joined:
    Feb 27, 2009
    Messages:
    5,062
    Location:
    Colorado
    For my P85 Sig, and I believe this works for most S85's, I have found the following numbers to be good.

    • 290 Wh/mi — DC Energy Out of the Battery. This is what you will see on the car's energy display. If you do a single drive from charging with no off charger preheating or time for the Vampire to suck charge from the battery, then if the car shows 290 Wh/mi, the actual miles driven should be very close to rated miles used from the battery.
    • 300 Wh/mi — DC Energy into the Battery. This is what you will see for Energy from a Supercharger or CHAdeMO. This is larger because of the approximately 97% efficiency of energy in to energy out of the battery.
    • 333 Wh/mi — AC Energy from the Wall. This is larger because of the approximately 90% effiiency of the on-board car charger converting AC to DC. This leads to the approximation that AC charge rate is about 3xkW of the AC charger; 240V*40A=9.6kW and 9.6kW*3mph/kW=28.8mph; a 40 Amp, 240 Volt AC charge source provides about 28 rated mph.

    For the P85D, all the numbers are a few percent higher, slightly less EPA efficiency. I don't have any personal experience, but the energy numbers should all be slightly lower (higher EPA efficiency) for the 85D, 70D and 60.
     
  15. JohnQ

    JohnQ Active Member

    Joined:
    Jan 1, 2012
    Messages:
    1,585
    Location:
    Redding, CT

    There we go. I know the 300 Wh/mi is thrown around quite often but I've found that your number is closer to what I experience ...
     

Share This Page