Kwh, charge time, EV range

Discussion in 'Prime Plug-in Charging' started by crewdog, Dec 12, 2016.

  1. inferno

    inferno Senior Member

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    Would density be the same? Don't tires deflate in pressure a little bit in the winter because air is less expansive?
     
  2. Lee Jay

    Lee Jay Senior Member

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    They do, but as I said, I inflated them before the cold run so the gauge pressure was the same in both runs.
     
  3. Trollbait

    Trollbait It's a D&D thing

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    There is more than the engine that needs to warm up before the best efficiency is achieved; other fluids and grease will sap more energy while cold. Then things like the tires will never be able to get up to their ideal temperature during the winter.

    The increase in air density becomes a bigger factor at highway speeds.
     
  4. EV-ish

    EV-ish Active Member

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    How much does the tyre temperature matter if they are well inflated ?
     
  5. Lee Jay

    Lee Jay Senior Member

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    Based on my test, quite a lot.
     
  6. EV-ish

    EV-ish Active Member

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    I didn't get the impression from the post of your test that you could isolate tyre temperature amongst the myriad of effects that add to rolling resistance in a cold car.
     
  7. Lee Jay

    Lee Jay Senior Member

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    Things that stayed the same:
    • Starting location
    • Starting speed
    • Air density
    • Wind (near zero)
    • Propulsion (zero - clutch pressed in)
    • Tire gauge pressure
    Things that changed:
    • Tire temperature
    • Transaxle lubricant temperature
    • Ending speed
     
  8. EV-ish

    EV-ish Active Member

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    ICE temperature ?
    Lubricant temperature for the axles and differential ?
    Engine Oil temperature ?
    Road resistance ?
     
  9. Lee Jay

    Lee Jay Senior Member

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    Irrelevant - not connected to the wheels (clutch pushed in).

    I mentioned that one.

    The roads were dry in both cases, and it was the same road.
     
  10. EV-ish

    EV-ish Active Member

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    Pushing in the clutch does not stop the ICE from turning, or most parts of the drivetrain.
    Just as tyres are stiffer with colder temperatures, I suspect the same physics applies to roads.

    I am not saying that your conclusion is wrong, but that it is premature and cannot be deduced from your test.
     
  11. Lee Jay

    Lee Jay Senior Member

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    Which just means the ICE draws more gas to keep everything turning. It doesn't affect the test since the test was a coast down test, not a fuel consumption test. The only thing that matters is what's affecting the coasting performance of the car, which the ICE doesn't when it's not connected to the wheels.

    Roads aren't elastomers.
     
  12. EV-ish

    EV-ish Active Member

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    I don't know what an elastomer is in this context but roads most certainly do deform under weight.
    I understand your point about the clutch, but I'm imagining the rotating parts after clutch that now have their frictions added to rolling resistance instead of offset by the ICE rotation.
     
  13. Lee Jay

    Lee Jay Senior Member

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    Rubber is an elastomer. It has both elasticity (like metal, rock, etc.) and viscosity (which absorbs energy). The road just has elasticity and very little energy absorbtion. The damping coefficient could be different by a factor of 100 between the road and the tires.

    As I said, that's the lubricant in the transaxle. That could have affected things. I doubt it was the driving factor, though, for a variety of reasons.
     
  14. Lee Jay

    Lee Jay Senior Member

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    Not relevant - that's about static friction - the ability of the tire to not skid. It doesn't have anything to do with rolling friction.
     
  15. priuscatprimeguy

    priuscatprimeguy Senior Member

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    Used scheduled charging. Set for 7am . Started charging at 3:15 am. Finished charging at 5:50 am. Outside temperature was 12 degrees . Drove 25 mph for 2 miles then up to 45 mph afterwards . ICE did not come on, had breakfast at IHOP went to chargepoint , charged then went to next destination at 35 mph. ICE came on. Outside temperature 14 degrees

    Posted via the PriusChat mobile app.
     
  16. bisco

    bisco cookie crumbler

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    that's odd. was it 14 the whole time?
     
  17. inferno

    inferno Senior Member

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    What if the battery if preheated? Do you have that mode on?
     
  18. priuscatprimeguy

    priuscatprimeguy Senior Member

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  19. bisco

    bisco cookie crumbler

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    i've never had the ice come on after i've made the first ev drive of the day. are you sure it wasn't the 200 mile cleansing?
     
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