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

Basic question, I think - wh/mile

Discussion in 'Model S: Battery & Charging' started by Stimyg, Jun 2, 2013.

  1. Stimyg

    Stimyg Member

    Joined:
    Feb 17, 2013
    Messages:
    80
    Location:
    New York
    What does the wh/mile average reading actually represent, exactly? And how exactly is it using that to calculate range (the range reading in the energy screen)? Is it simply taking the remaining charge in the battery, dividing it by the wh/mile average, and then giving you the range?

    Ie, if I have an 85000 watt car, and average 300 wh/miles, it would go 85000/300= 283 miles on a full charge?
     
  2. jerry33

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

    Joined:
    Mar 8, 2012
    Messages:
    12,751
    Location:
    Texas
    Wh/mile is the average amount of power used to propel the car over the distance indicated. No, it wouldn't go 283 miles because you don't get to use all 85 kW. At most only about 81 kW is used. Also the calculation would only work if you continue to drive in the same manner.
     
  3. Stimyg

    Stimyg Member

    Joined:
    Feb 17, 2013
    Messages:
    80
    Location:
    New York
    Ok, but if I have 81 available KW, and I average exactly 300 wh/mi, would I go 81000/300 = 270 miles? And is that why they draw the dotted line at 300 wh/mi - because if you average that you will get approximately the rated range?

    Again this is not a range question Im just trying to understand what everything represents. Thanks.
     
  4. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,731
    Location:
    Smithfield, VA
    To be clear on semantics: it should be 81 kWh, not 81 kW. kW is a unit of power, whereas kWh is a measure of some amount of power applied over some time--a unit of energy--the amount of energy stored in your pack.

    *IF* you have 81 kWh available for use, and *IF* you average exactly 300 Wh/mi (energy use per distance), then yes, you would be able to go 270 miles.
     
  5. deonb

    deonb Active Member

    Joined:
    Mar 4, 2013
    Messages:
    3,019
    Location:
    Redmond, WA
    Yes, tracking the dotted line at 300 wh/mi will get you the EPA rated range... sort'a. The math doesn't quite work in practice. It's actually not difficult getting the exact rated range in summer (easier than any other car I've owned), but I don't always get it at 300 wh/mile. Some days at 290, others at like 305.

    I think the difference comes from that wh/mi is actual current that got measured (accurate), where capacity is a charge measured on the battery. An SOC measurement is highly dependend on factors such as temperature, so I think it is only accurate to within like 5%.

    PS: 81 kWh is a range charge. A standard charge is 72 kWh.
     
  6. Stimyg

    Stimyg Member

    Joined:
    Feb 17, 2013
    Messages:
    80
    Location:
    New York
    Great, that was my next question: so 72 kwh is the available battery on a standard charge? Good to know.

    Thanks for the replies, I think I got it now.
     
  7. Jeff Andrews

    Jeff Andrews Member

    Joined:
    Jan 2, 2013
    Messages:
    190
    Location:
    San Luis Obispo, California, United States
    Does anyone know the standard and range charges for a 60?

    Sent from my Nexus 4 using Tapatalk 2
     

Share This Page