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Chevy Bolt - 200 mile range for $30k base price (after incentive)

Discussion in 'Electric Vehicles' started by FredTMC, Jan 9, 2015.

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  1. McRat

    McRat Active Member

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    GM EVs do not have a locked "base number" for the range. It is a dynamic calculation based on your past driving, current driving, and temperature. One of our Volts said 51 miles on my cellphone and dash however I drove it at 65 mph for 59 miles today and had 0.8 kWh remaining. So the error can go either way. Looking at the phone, it says 54 now.

    Something interesting though. Road surface and type of weather makes a fairly big difference. That same drive in heavy rain? I ran out of battery at 48 miles at the same air temperature and speed. No wind to speak of, round trip, no heater (only 48°F). The force of the rain and increased rolling resistance hammered the range.

    But for your specific example, you'd need a second data point. Any other car, EV or ICE, doing the same route, same time. 50% of EPA range is excellent climbing the grade to Flagstaff, or driving down a gravel fireroad. It would be tragically bad on a clear day at 75 mph.
     
  2. McRat

    McRat Active Member

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    BTW - They are liars, just in case you were not aware. They were running the heat at max with seats etc, not "minimum heat, no seats". Look at the right. 7 kW sitting parked. That's about maxed out.

    Chevrolet Bolt EV - RPM 2 (3).jpg
     
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  3. Jeff N

    Jeff N Active Member

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    #4843 Jeff N, Feb 10, 2017
    Last edited: Feb 10, 2017
    That could be completely normal. The full power of the heater could come on periodically to heat the circulating "coolant" of the cabin loop even if they had set the target temperature to 62F. I haven't driven my Bolt in 9F weather so I can't speak to that but the heater power draw does vary somewhat over time even when used when it is only 50F outside with a target of 70F inside.

    If this really is an unusual power use during winter 9F driving there are a variety of possible explanations. One is whether in playing around with the climate controls they could have switched from "auto recirculate" to "recirculate off" so the heater would be constantly heating freshly drawn outside air. Who knows?
     
  4. Saghost

    Saghost Active Member

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    They stopped in the middle and charged, according to the article. 256 Wh/km = 410 Wh/mile.
     
  5. scaesare

    scaesare Active Member

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    They lost a bit more than 40% of their range in weather 20+ degrees below freezing. Not surprising, and more of an indicator of the current state of Li-ion and the tradeoffs in temp extremes than anything specific with the Bolt, IMO.
     
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  6. Saghost

    Saghost Active Member

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    Keep in mind, that's a GM range indicator. Unlike Tesla's "rated" range, GM uses a dynamic estimator based on recent consumption - so in a scenario like this, the loss looks a lot worse than it is, as the estimate dips not only for the energy used but also because the car expects to use more energy per mile.

    Because of this, you really can't draw any conclusions from the range estimates at any point in the drive IMHO.

    The ~410 Wh/mile is a real number - rather high for ~60 mph, but I haven't driven much in 9F weather to see how painful that is.
     
  7. scaesare

    scaesare Active Member

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    Yeah, good point.

    IIRC, the bolt seems to use nearly all of it's 60kWh "advertised" pack size from what we saw. So assuming a full 238 mile range, that implies ~248WH/mi under good conditions. Using 410 instead is not too out of line based on what I see on my S in cold weather...

    Assuming 59kWh of the pack is available, that would be ~144 miles range or so... definitely in the neighborhood of the estimate.
     
  8. Zoomit

    Zoomit Part 3 Awaiter

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    I was curious so ran the numbers for context. Air density increases 14% when the temperature lowers from 75F to 9F. This increases aerodynamic drag an equal amount. At highway speeds, overcoming aero drag accounts for about 75% of the energy required. So in this case, the temperature's effect on aero drag accounts for ~10% of the range loss [15% x 75%].

    The decrease in ambient temperature also affects the battery temperature (and hence chemical reaction) plus the tire rolling resistance, to some degree.

    Concerning the Bolt EV usable capacity, there are some indications that the usable capacity is slightly above 60 kWh.
     
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  9. SageBrush

    SageBrush Active Member

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    #4849 SageBrush, Feb 10, 2017
    Last edited: Feb 10, 2017
    348 N of air resistance at 75F and 100 kph,
    So by your air density number, another 48.7 N air resistance at 9F

    That works to 48.7*27.8/62 = 21.8 Wh additional per mile.

    I can easily imagine them using 4 kW for heating and defrosting duties,
    So another ~ 70 Wh per mile

    The remaining difference is a mixture of
    Colder tyres, and perhaps under inflated tyres for that cold day
    Whatever wind was blowing that day
    Any elevation change

    This Montreal story is a realistic result for an owner that does not know how or want to optimize EV driving in cold weather.
     
  10. McRat

    McRat Active Member

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    There is significant additional rolling resistance as temperatures drop since synthetic rubber's pliability increases with temperature. You see this in ICE cars with low pressure (under 80 PSI) tires on cold days at low speeds. Not so much at 80 PSI and higher, as there is little flex due to both pressure and thicker and more numerous tread plies.

    But also the rolling surface must be flat. Snow, ice, standing water, expansion cracking, decay, potholes, etc, take a heavy toll. Try to push a car on a torn up road by hand. Or pop it in neutral and hit a big puddle.

    But in reality, I'm thinking that was virtually a perfect storm. At an honest 62 mph steady state as claimed, on flat roads in mild weather, you normally exceed the EPA combined range significantly in all cars, not just EVs. So you are not starting from a 238 number but about 10% higher or about 260mi roughly. So about 50% decay at low highway speed.

    I have a hunch the next person who tests at 0°F will see a longer range than 137 mi with "no seat heat, and low HVAC setting, at 62 mph", But I could be wrong.
     
  11. RiverBrick

    RiverBrick Active Member

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    #4851 RiverBrick, Feb 10, 2017
    Last edited: Feb 10, 2017
    For the 9F test, they picked up a brand new Bolt (4 miles on the odometer) from the dealer's garage , so it should have been warm . Note sure why the predicted range would have adjusted to 350 km from 383 at that point.

    The under inflated tires theory is plausible. Garages are notorious here for not taking exterior temperature into account when inflating tires indoors.

    I have driven the route many times times in an S. I lose about 35% of rated range at -4F at 65 mph (the speed trucks are electronically limited to here.) When it is 9F, I can't compare, because I follow the passenger car traffic at 73 mph.
     
  12. RiverBrick

    RiverBrick Active Member

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    #4852 RiverBrick, Feb 10, 2017
    Last edited: Feb 10, 2017
    I was mistaken in writing 2.42 miles/kWh for the entire trip, as pictured it was just for the first 62 miles. Also, it was measured at the end of their recharge stop. Does the posted trip consumption at that point take into account energy used for heating while stopped?

    Edit: One other mention is that you may lose 2%-3% efficiency on driving Quebec highways compared to typical ones in the USA. The asphalt is very rough here.
     
  13. gameon

    gameon Member

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    ah..most of the salesman think the same for oil...rest is above their head ;)
     
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  14. Saghost

    Saghost Active Member

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    TFLCar just gave a Bolt interview/test ride on the Bolt:



    A couple interesting tidbits.

    This is the first video I've seen that showed the different screen modes for the driver's panel, which seem pretty similar to Volt Gen 2 from what I saw. I was especially interested by the description of gray boxes on the left side that show how your current driving is trending relative to the predicted/min/max range numbers. That hadn't come up before, and sounds pretty useful - along the same line as Tesla battery on arrival prediction, more immediately helpful but not quite as useful overall I'd think. I'll be interested to see a better description of this feature in the future.

    Also, I don't know how significant it is (to some extent it's common sense,) or how much to read in to it, but the chief engineer makes the comment that the EPA cycle is the goal and the design ("range number" was targeted towards that. The interviewer doesn't quite understand that large EV motors aren't much less efficient at low power levels than smaller motors, and the engineer doesn't really explain that part to him, so they go on about it for a while...

    https://www.youtube.com/watch?v=EnVspgrZUkI
     
  15. 3Victoria

    3Victoria Active Member

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  16. RiverBrick

    RiverBrick Active Member

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    You cannot jump to the conclusion that they are liars. The image is from their CCS stop. Doesn't the lightning bolt icon mean the heat was running off shore power? As long as consumption isn't counted when the car is off or in park, cranking the heat to max when quick charging would only help their efficiency while on the road.

    Now that Bolts are starting to be delivered in Canada, more cold-weather trip-reports are coming in. Here is the screen from a 73-mile trip in 10F weather. They started in a warm garage, otherwise, would there have been battery conditioning?

    The owner reports he was using Michelin Xice-i3 tires and followed posted limits, which would have been roughly 80% 62 mph, 15% 43-55 mph and 5% 31-37 mph. Heat set to 68F. He did 21% better m/kWh wise than the reporter. Part of it is thanks to dropping 450 feet in altitude.

    Photo thanks to Stephane Tremblay.
    16603068_10155213868048814_4042516155948680339_n.jpg
     
  17. Yggdrasill

    Yggdrasill Active Member

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    I've been working on a range spreadsheet for the Model 3, but I've also included the Bolt. Wind matters *a lot*, so with low temperatures and a headwind, it's not surprising to get under 150 miles. Model 3 high speed range
     
  18. scaesare

    scaesare Active Member

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    Would have allowed for ~177 miles using 60kWh of energy. That's losing 26% of the rated 238 range in weather 20+ degrees below freezing. Not bad.

    Although like you say with an elevation drop. And I suspect 68 deg setting in 10 deg weather might be a bit conservative for many. I'd say the cold weather performance for those conditions is such that counting on losing ~1/3rd of your range is likely... similar to what I see on my S.
     
  19. McRat

    McRat Active Member

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    Earlier in the thread, there was debate about whether the CCS infrastructure today would allow a Bolt EV to travel to Las Vegas from SoCal. Apparently somebody has just done that. He cut it very close on the return trip by only charging to 80% before leaving Vegas to Victorville. But the trip up with 90% charge did it with room to spare, even with the Mountain Pass, CA altitude of over 4,700'. Note, there is no CCS charging in Baker or Barstow.

    So one of the most common long trips that Californians make was easily accomplished by the Bolt EV without any improvement in infrastructure yet. Only the Teslas and the Bolt BEV's can make this trip without long layovers, if at all.
     
  20. JohnSnowNW

    JohnSnowNW Active Member

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    Define "easily accomplished." How long did it take him, and how did he drive the vehicle?
     

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