There's always a crossing point. At 1mph, rolling resistance is by far
the dominant factor. At 70mph, for most vehicles, air resistance is by
far the dominant factor. At some point, these factors are 50-50. For a
"slippery" car, that point will be higher than for a non slipper car.
But rolling resistance wasn't the only factor brought up. The other
principal factor is the losses from regen. You don't get 100% of the
energy back, even if there were no air resistance. Empirical data seem
to show that city driving with a lot of stop & go and a lot of hills
significantly increase the energy/distance usage.
Peri
------ Original Message ------
From: "Michael Ross via EV" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>; "EVDL
Administrator" <[email protected]>
Sent: 04-May-16 8:18:18 AM
Subject: Re: [EVDL] EVLN: Upgraded 2016 Tesla-S 90D is the first
300mi/483km production Electric car
Weight is NOT a dominant factor. Air resistance trumps it by at least
an
order of magnitude. Combined rolling resistance is dependent on contact
patch size which is why semis are pumped to 100psi. With good active
suspension you can have high inflation pressure tires and not
compromise
ride quality or rolling resistance.
People always think RR is big deal because if you keep the pressure up
it
becomes a big deal.
On May 3, 2016 3:45 PM, "EVDL Administrator via EV" <[email protected]>
wrote:
On 3 May 2016 at 8:53, tomw via EV wrote:
> The S uses quite a bit more power on accessories than most
conversions,
> and most drivers likely usually have climate control on.
But that wouldn't affect EPA range ratings, would it? Aren't those
measured
with aircon and other stuff turned off?
Or is it burning off energy on accessories that CAN'T be turned off?
That
would kind of stink. :-(
> It also has a very low drag coefficient, so low that it has the
same
> CdA as my little Suzuki Swift. That, and its 4700+ lb weight
results in
> its drag and rolling resistance forces being equal at around 60-65
mph
> compared to around 45 mph for most vehicles.
Yeah, I'd forgotten, it's (please forgive me) an obscenely heavy car.
So friction losses are dominant. Hmm.
> The energy/mile used moving at ~ constant speed in city driving
would
> have to be low enough relative to highway driving to compensate for
> that energy lost during each acceleration, and that will depend on
> distance driven between stop/starts.
Here again, the EPA method enforces a formula. So I wouldn't think
this
would affect Teslas more than other EVs.
What is incontestable is that the Leaf's city range is greater than
its
highway range, but the Tesla's city range is SHORTER. It's hard to
avoid
the notion that a Tesla acts more like an ICEV than other EVs do,
wasting a
significant amount of energy "idling." Ouch.
David Roden - Akron, Ohio, USA
EVDL Administrator
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