LEAFfan
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Re: Reliable EV Data for Comparison

Wed May 12, 2010 9:20 pm

garygid wrote: The 60 mph constant is similarly unrepresentative of real-world driving, but the percentage drop from the very similar 45 mph test is useful. Going from 45 to 60 (15 mph increase) shows about a 30% reduction in range. One could easily suspect that increasing another 15 mph (to a constant 75 mph) would result in more than another 30% reduction in range.
LOL, maybe in CA 60mph is unrepresentative, but here in AZ, where there are speed cameras everywhere (not complaining), 60 is very common. Actually, I usually drive in the right lane at 58-59mph and achieve 48-50MPG using cng. :) In fact, I'm willing to bet that I can beat a Prius on the highway mileage (can get low 40's in the city).
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darelldd
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Re: Reliable EV Data for Comparison

Wed May 12, 2010 9:25 pm

EVDRIVER wrote:60 MPH is not a good freeway measure
It is a great measure if you drive 60!
this is why the old Thinks were limited to 57 MPH even though they could go faster.
All production cars were artificially limited for speed. They could all go faster than their governed top speed. They weren't limited to increase range however.
At least they are more realistic on the RV4.
More realistic than what?
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darelldd
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Re: Reliable EV Data for Comparison

Wed May 12, 2010 9:29 pm

LOL, maybe in CA 60mph is unrepresentative
Pffft. In LA it is common to see average freeway speeds of 5mph. When driving an EV for range, congestion is your friend! :)
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evnow
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Re: Reliable EV Data for Comparison

Wed May 12, 2010 10:43 pm

darelldd wrote:Pffft. In LA it is common to see average freeway speeds of 5mph. When driving an EV for range, congestion is your friend! :)
Exactly - I was wondering which city is this where during daily commute people can hit 70 or more ! Most places would be happy with 40.
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EVDRIVER
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Re: Reliable EV Data for Comparison

Thu May 13, 2010 12:00 am

darelldd wrote:
EVDRIVER wrote:60 MPH is not a good freeway measure
It is a great measure if you drive 60!

Not too safe where speeds are posted at 70 but depends on where you live. I suppose it is good if you drive 55 as well.
this is why the old Thinks were limited to 57 MPH even though they could go faster.
All production cars were artificially limited for speed. They could all go faster than their governed top speed. They weren't limited to increase range however.

I met the person in charge of the Think efficiency calculations and he stated that the only reason the speed was limited was for efficiency, that was determined to be the max speed they could do without large compromise and 55 was actually much better however they felt it was too slow for safe freeway use and consumer acceptance. He even gave me the original calculation notes of the early models for efficiency, range, etc. The new Think models will do at least 65 if not 70, driving 55 on the freeway in some places can be quite dangerous at times. The numbers are quite interesting to examine at various speeds.

At least they are more realistic on the RV4.
More realistic than what?
Then the inflated figures people quote on the internet and elsewhere. Many inflated or incorrect figures are cited by people who have never even been in an EV yet are experts at inaccurate number gathering and interpolation on paper. It's like believing it's remotely possible for the Leaf to do 0-60 in 5 seconds just because it's electric. Most people don't understand the efficiency differences between ICE cars and EVs, the EV penalty is much higher than an ICE.

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EVDRIVER
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Re: Reliable EV Data for Comparison

Thu May 13, 2010 12:04 am

evnow wrote:
darelldd wrote:Pffft. In LA it is common to see average freeway speeds of 5mph. When driving an EV for range, congestion is your friend! :)
Exactly - I was wondering which city is this where during daily commute people can hit 70 or more ! Most places would be happy with 40.

I drive the posted speed limit in many places in CA of 70 and get passed, during rush hour. I also commute between cities and rarely do people drive under 60. Really depends where one lives and it was very uncomfortable being restricted to about 56.

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mwalsh
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Re: Reliable EV Data for Comparison

Thu May 13, 2010 6:22 am

EVDRIVER wrote:I drive the posted speed limit in many places in CA of 70 and get passed, during rush hour.
Indeed. And I've seen drivers be very "aggressive" in the car pool lane, when they think the car ahead isn't going fast enough for them (and in some instances I'm talking about cars that are already doing 70-75 mph).
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AndyH
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Re: Reliable EV Data for Comparison

Thu May 13, 2010 10:11 am

This type of back and forth is exactly why there's such a sense of disconnect between REAL average speeds and what folks believe because they saw 80 on the speedo during their commute.

Please please don't miss the significance of the 30mph average speed used by the transportation industry for scheduling maintenance.

Before leaving the road for my home office, I drove between 25,000 and 35,000 miles per year supporting customers and working trade shows. In spite of all the time spent on I35, I10, trips to the SF Bay area and annual trade shows in NJ, my average speeds are in the low 30s.

Comparing any vehicle's performance against an erroneous concept - that a driver instantly accelerate to 80mph and stay there until they instantly decelerate to a stop during every drive - will provide a bad result every time.

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Re: Reliable EV Data for Comparison

Thu May 13, 2010 11:32 am

Here's real-world lithium EV data that I've personally collected. Maybe it'll give another look at the 'highway driving' myth. ;)

Most battery or cell discharge curves are from constant loads - like these from my shop:
Image

Yet there's nothing constant about the load on a battery on the road:
Image

Here's GPS data from a real-world EV drive:

Image

There was no significant traffic and only the first 400 feet was on a road with a 45mph limit - all others were 55 to 70mph. In spite of the appearance of a 60mph drive, average speed for this 26 mile trip was 37mph.

Andy

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TimeHorse
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Re: Reliable EV Data for Comparison

Thu May 13, 2010 11:45 am

AndyH wrote:This type of back and forth is exactly why there's such a sense of disconnect between REAL average speeds and what folks believe because they saw 80 on the speedo during their commute.
Preaching to the choir, sir! That's why I want a power curve so we don't have to so much extrapolate as simply run the numbers. Granted, a true power curve is not really easy to come by. Tesla has one, but we're not going to see one anytime soon -- at least not likely before August never mind December. And if we're to pony up the cash in August I want to at least know if it's gonna get me there and back again. The EPA has some very interesting test vectors that they have under their Dynamometer page that I've been analyzing and if anything I'd rather go by that then any top speed. I like the US06 not because it goes to almost 80 mph. In my state of Virgina I'd never drive that fast even if I could since I don't want a permanent Class-6 Misdemeanor charge on my criminal record. Yes, in Virginia we make routine driving infractions part of your criminal record and for you Californians coming here, we have another Class-6 Misdemeanor called 2-Abreast meaning you can't share a lane, even if you're on a very narrow motorcycle like y'all do back home!

But enough of my crazy East-coast state. The point is, I drive an average of 51 mph to work. That's by no means my top speed. I hit speeds well in access of that (though never more than 14 over the limit -- did I mention the Class-6 Misdemeanor??) and a number of local roads. That's why US06 is such a good measure for me. It has acceleration, deceleration, reasonable maximum speeds and an average speed of about 48 mph, much closer to my 51.

But anyway, thanks for the numbers, sir, as those 3 data points are just what I need, in theory, to compute the power curve for the cars listed. Not the Nissan LEAF, alas, but if I can get it to work for the others, I know I'm on the right track!
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