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

Range vs. air temperature according to AAA

Discussion in 'Model S: Battery & Charging' started by John Vig, Jun 23, 2014.

  1. John Vig

    John Vig Member

    Joined:
    May 29, 2014
    Messages:
    21
    Location:
    Colts Neck, NJ, USA
    From the July/August 2014 AAA World, p. 65, "According to new AAA research conducted...in Southern California, electric-vehicle range can be reduced by an average of 57 percent based on the temperature outside." The testing did not include the Tesla; only the Nissan LEAF, Ford Focus E and Mitsubishi i-MiEV were included. "The average range was 105 miles at 75 deg F, but it dropped to 69 miles per full charge at 95 deg F. Cold weather had a more dramatic impact, dropping the range to only 43 miles when the temperature was held steady at 20 deg F."

    I'm a new owner. Where can I find range vs. outside temperature info for the Tesla? Does Tesla include the effect of temperature on the driving range that is displayed?
     
  2. Baalik

    Baalik New Member

    Joined:
    Jun 11, 2014
    Messages:
    2
    Location:
    Czech Republic
  3. djp

    djp Roadster 2.0 VIN939

    Joined:
    Aug 28, 2011
    Messages:
    1,108
    Location:
    Toronto, Canada
    The calculator on Tesla's website includes the effect of temperature on range:

    Your Questions Answered | Tesla Motors

    Battery heating has a big impact when temperatures are below 50F. You'll get less range from short intermittant trips than a long continuous trip since the pack needs to be warmed up to 50F at the start of each drive.
     
  4. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,734
    Location:
    Smithfield, VA
    To be clear, the battery itself is not losing range in the cold. It's storing the same amount of energy. You just typically have other draws that consume energy (and the battery cannot put out as much *power*--or receive as much using regen--when cold).

    In the Model S you can enable "Range Mode", which will prevent any active heating of the battery unless it's REALLY cold (and 20°F does not qualify as REALLY cold). Instead, the battery pack very slowly warms up passively from the small losses in power production. Range mode will help you save considerably on range.

    If you feel you need to heat the battery, you can preheat the battery while plugged in before you leave using power from the wall. Same goes for the cabin heating.

    There are other things about winter that increase energy use that have nothing to do with EVs:

    -The air is more dense, therefore drag is higher.
    -It is generally windier in the winter--therefore higher drag forces.
    -There is often more precipitation (rain, snow) and less traction (rain, snow, ice) which contributes to losses.

    So, there are plenty of things you can do to reduce energy loss in the winter for those drives when you need the range:

    -Preheat the battery pack while plugged in.

    -Preheat the cabin to a warm temperature while plugged in. The materials in the cabin will store some of the heat and give it back while you drive.

    -Use the seat heaters to reduce the cabin heating needs.

    If you follow these tips, I've found a loss of about 20% range in the winter (temps around freezing).
     
  5. kjl

    kjl Member

    Joined:
    Jun 4, 2013
    Messages:
    91
    Location:
    SF Bay Area
    Huh, range mode does that? I wonder if I'm doing any long term damage to my battery by leaving it in range mode all the time (by not letting it control the temp of the battery as tightly as it wants)... I was under the impression that all range mode did was limit the climate control, and I've been leaving my car in range mode all the time simply because the higher fan speeds are really, really loud.
     
  6. Vger

    Vger Active Member

    Joined:
    Apr 10, 2009
    Messages:
    1,683
    Location:
    Salt Spring Island, BC, Canada
    I'd say in the Bay Area, you have absolutely no worries. It is only pack heating that is limited, and only in moderate cold. When it gets really cold, the pack heater will protect the battery power delivery. Also, bear in mind that a cold battery is a happy battery. It might be less powerful, but it is also chemically degrading very very slowly. High heat is the killer.
     
  7. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,734
    Location:
    Smithfield, VA
    You are absolutely fine leaving the car in range mode. Cold is fine for the battery (better, as Vger pointed out). If the battery is hot, it will still cool it as necessary. If it is REALLY cold, it will still heat it as necessary.
     
  8. TonyWilliams

    TonyWilliams Active Member

    Joined:
    Jun 11, 2012
    Messages:
    1,002
    Location:
    San Diego - Tesla powered Rav4 EV
    Well, in a battery without temperature control (like the LEAF), the capacity is reduced by cold and increased by heat.

    We use a rule of thumb of minus 1% per 4F degrees below 70F and plus 1% per 8F above 70F.

    So, a 30F battery has 10% less stored energy for you to consume and a -10F has 20% less stored energy.

    The Nissan LEAF has 21.3kWh of usable stored energy when in new condition at room temperature.
     
  9. PhilBa

    PhilBa Active Member

    Joined:
    Apr 20, 2013
    Messages:
    1,355
    Location:
    Seattle
    I'm kind of stuck on the 57% number in the OP. Where did that come from? From my experience, 57% is way more than I would expect to see. Well maybe in Frozen Monkey Bay, Alaska... Tony's numbers are more in line with my expectation.

    By the way, 50F is a very sharp cut off for non-range mode. The other morning it was 48F in the car and I got 380 wh/mi. Same day mid morning, it was 54F and the exact same route and basically same driving style yielded 322 wh/mi. 48F was 18% worse, I assume mostly due to battery heating.

    Oh and a slight semantic point - a cold battery doesn't have less stored energy, it's just less usable energy. If you warm it up, the usable amount increases.
     
  10. dsm363

    dsm363 Roadster + Sig Model S

    Joined:
    May 17, 2009
    Messages:
    18,235
    Location:
    Las Vegas, NV
    AAA apparently took a Leaf and put in a temp controlled room and tested the range to at those numbers. Certainly don't apply to the Model S to that degree.
     
  11. Cottonwood

    Cottonwood Roadster#433, Model S#S37

    Joined:
    Feb 27, 2009
    Messages:
    5,062
    Location:
    Colorado
    EV Trip Planner does a pretty good job at calculating the needed power to keep the cabin and battery warm. Go simulate some of your trips in winter, spring, and summer; see what the results are.

    I've found the biggest help for winter range is to preheat the battery by charging just before you leave without being in range mode, and preheating the cabin. In fact, before leaving on a winter hypermile trip, or at winter Supercharger stops, I will often set the cabin heat up to 85˚ F. with the app to store extra heat in the interior of the car.
     
  12. dsm363

    dsm363 Roadster + Sig Model S

    Joined:
    May 17, 2009
    Messages:
    18,235
    Location:
    Las Vegas, NV
    Has anyone seen a 57% hit in the winter though in a Model S?
     
  13. Cottonwood

    Cottonwood Roadster#433, Model S#S37

    Joined:
    Feb 27, 2009
    Messages:
    5,062
    Location:
    Colorado
    #13 Cottonwood, Jun 25, 2014
    Last edited: Jun 25, 2014
    I've been through some pretty good winter drives and have seen nothing like this. See Realistic Range Expectations in Crummy Winter Weather - Hypermiling in the Winter...Brrr]

    From that post:

    I drove 228 miles with 2,000 feet elevation gain (12-14 equivalent miles, total 240 equivalent miles) in on a range charge of 255 miles in a P85, arriving with 13 miles left in the battery. The temperatures on the route ranged from 40˚ F. at the start to 12˚ F. on some passes, and probably averaged 26˚ F. or so.
     
  14. Zextraterrestrial

    Joined:
    Mar 11, 2010
    Messages:
    3,636
    Location:
    Humboldt/Los Altos
    I drove from Springfield to Salem in deep and some packed snow and I had to sit stopped on I-5 near Salem in low 20F temperatures for 2 hours. this was 70 miles total and I only saw 435 Whr/mi average. most of the drive was ~ 45 mph though (any more and I was fishy...the guy that passed me was stuck in the shoulder- 3-4' of powder shortly after)

    hauling ass half way / half way in snow to Springfield from Grants Pass was ~ 400Whr/mi (42F down to 28F)
     
  15. Todd Burch

    Todd Burch Electron Pilot

    Joined:
    Nov 3, 2009
    Messages:
    4,734
    Location:
    Smithfield, VA
    I don't debate your numbers, but I am suspicious that it's from a change from 48F to 54F. Winds are usually light in the mornings as an inversion layer often sets up. As the sun heats up the surface for a few hours, this inversion layer bakes off and stronger winds aloft start to break down to the surface.

    Even if you didn't notice significantly stronger winds or gusts, a light breeze or the occasional light to moderate gust can have significant effects on Wh/mi. I'd put my money more on the reason being slightly stronger surface winds than a 6 degree change in temperature. I doubt there's any battery heating at 48F.
     
  16. TonyWilliams

    TonyWilliams Active Member

    Joined:
    Jun 11, 2012
    Messages:
    1,002
    Location:
    San Diego - Tesla powered Rav4 EV
    And they likely ran the cabin heater. So, the battery "usable" losses from cold are well known and quantifiable.

    The HUGE consumption of energy from the heater is well known, too.
     
  17. paulkva

    paulkva Member

    Joined:
    Jul 22, 2013
    Messages:
    567
    Location:
    Falls Church, VA
    Over the long haul I haven't. But I've certainly seen individual trips where I've averaged over 500 Wh/mi (e.g. in snow and ice). I've seen my commute (10 mi round-trip) cost me well over 400 Wh/mi in the winter, although not every day. Lately in milder weather I've been getting closer to 290 Wh/mi. The problem, of course, is that's a pretty short trip so I'm sure the measurements are far less accurate.
     
  18. djp

    djp Roadster 2.0 VIN939

    Joined:
    Aug 28, 2011
    Messages:
    1,108
    Location:
    Toronto, Canada
    The target temperature for the battery heater is 50F, so it's possible that heating is responsible for the difference.

    Model S Overall Thermal Management
     
  19. David_Cary

    David_Cary Member

    Joined:
    Dec 17, 2012
    Messages:
    607
    Location:
    Cary, NC
    It is possible AAA tested an older Leaf with resistance cabin heating. The Tesla (and newer Leafs) have a heat pump. Pretty big difference.

    As far as the loss of range in the heat, the AAA test is obviously seriously flawed. Reduced air density and more usable energy from the battery more than makes up for a/c use in my experience. I get about 100 mile range at 95 degrees in a Leaf.

    AAA has no credibility in regards to changing the automotive paradigm. This article was a hit piece on EVs in general
     

Share This Page