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

Average wattage for driving at 55mph or in town

Discussion in 'Model S: Battery & Charging' started by dspwhite, Nov 21, 2012.

  1. dspwhite

    dspwhite Member

    Joined:
    Nov 21, 2012
    Messages:
    9
    Location:
    UK
    I hear that the Model S's top end battery is capable of a whopping 270 kW of raw power (equivalent to around 140 of my 2kW kettles running simultaneously). However, that's presumably a maximum. What's the wattage (not watt hour) when driving at 55mph? Also what's the average wattage used when driving in town generally with?
     
  2. Johan

    Johan Took a TSLA bear test. Came back negative.

    Joined:
    Feb 9, 2012
    Messages:
    6,890
    Location:
    Drammen, Norway
    Reports are 300 W/mile at 55 mph. If you do the product of these two numbers (300 * 55) all units but W will cancell eachother out so the answer is 16500 W = 16.5kW which is consistent with driving for about 5 hours before having used up 82.5 kWh which is 55 mph * 5 hours = 275 miles (a little optimistic).
     
  3. dspwhite

    dspwhite Member

    Joined:
    Nov 21, 2012
    Messages:
    9
    Location:
    UK
    Thanks I get close to your result with the stats from some specs I looked up:

    85kWh = total battery capacity
    300 miles = capable distance traveling at 55mph

    85kWh ÷ (300miles ÷ 55mph) = 15.583333 kW

    Okay that's 'only' 8 kettles or toasters running at the same time now :)
     
  4. William13

    William13 Member

    Joined:
    Mar 19, 2011
    Messages:
    943
    Location:
    South Bend
    The car gives a one minute average power usage up dated every 6 seconds. I usually run under 300 watts per mile at 55 mph. But the power usage goes up rather steeply for each succeeding mph faster. It fun to watch.
     
  5. cinergi

    cinergi Active Member

    Joined:
    Sep 17, 2010
    Messages:
    2,170
    Location:
    MA
    You'll also easily draw 40-80kW to maintain highway speed going uphill (and conversely you can see 20kW or more doing regen at highway speeds down a hill). And these are just Massachusetts hills. I'm sure mountainous roads have some interesting numbers (would love to see someone share those!)
     
  6. Arnold Panz

    Arnold Panz Model Sig 304, VIN 542

    Joined:
    Apr 13, 2009
    Messages:
    1,341
    Location:
    Miami, Florida
    I'd also add that in windy conditions, with speed constant, being with or against the wind makes a huge difference. In the prevailing winds where I live, I see a 20-40 Wh difference in my average usage when driving into the wind versus with the wind.
     
  7. dspwhite

    dspwhite Member

    Joined:
    Nov 21, 2012
    Messages:
    9
    Location:
    UK
    Interesting. Perhaps the 16kW figure was a bit optimistic then, and assumed a flat surface with no wind. I like the way you're given the watts usage as you're driving!

    Perhaps you mean "300 watt hours per mile", since the watt is a power rating, rather than an energy amount.
     
  8. Jason S

    Jason S Model S Sig Perf (P85)

    Joined:
    Apr 20, 2012
    Messages:
    1,350
    Location:
    Rocklin, CA
    You are correct. And the power figures given so far match my experience, somewhat limited tho since I prefer 65-75mph. At 65 or so I see around 330 wh/m, 75 is 360 or so. It goes up, but not dramatically. I'll try to pay closer attention on my next highway trip.
     
  9. dspwhite

    dspwhite Member

    Joined:
    Nov 21, 2012
    Messages:
    9
    Location:
    UK
    #9 dspwhite, Nov 21, 2012
    Last edited: Nov 21, 2012
    Right, that's 21.45 kW and 27 kW respectively.

    I'm guessing that just like over 60mph, traveling at under 50mph will garner a higher (energy wasted) wh/m and that 55mph is the sweet spot?
     
  10. Jason S

    Jason S Model S Sig Perf (P85)

    Joined:
    Apr 20, 2012
    Messages:
    1,350
    Location:
    Rocklin, CA
    The folks who did the record with the Roadster traveled as flat as possible and fairly slowly, since it is air resistance that is most of the issue.

    A constant 35-40mph could get a very good range, but good luck finding a place to do that.
     

Share This Page