Preliminary RANGE results

[mwalsh]

More range talk:

http://wot.motortrend.com/6659795/green/real-world-results-2011-nissan-leaf-ev-range-may-differ-by-40-miles/index.html

Interestingly, it doesn't mention any situation where you would get any less than 60 miles per charge and even more interestingly we get our first hard estimate for highway driving WITHOUT climate control - 105 miles!:

"Engineers assigned to the project have long believed that the 100-mile range offered by the new 2011 Nissan Leaf electric vehicle is more than sufficient for most customers. Of course, that figure may vary depending on your driving habits -- and, according to the automaker, the Leaf’s real-world range may differ by as much as 40 miles.

Read more: http://wot.motortrend.com/6659795/green/real-world-results-2011-nissan-leaf-ev-range-may-differ-by-40-miles/index.html#ixzz0rVRbd3fz

“Depending on the way you use the air conditioning and the driving mode, the [range] varies largely,” Hidetoshi Kadota, chief engineer for the Leaf program, recently told Automotive News. “This is a physical characteristic of electric vehicles.”

Admittedly, accessory loads, driving styles, and a number of other variables play a factor in determining a vehicle’s total range, but electric vehicles’ ranges tend to vary quite wildly. You can thank the Leaf’s lithium-ion batteries for that. Although the chemistry is currently considered state of the art for EV power storage, their performance is altered by different climates. Both hot and cold temperatures affect the amount of energy the batteries can supply -- and, subsequently, the total range on a single charge.

Nissan suggests that drivers may see a swing of 40 percent in the Leaf’s range -- some may be able to eke out as much as 140 miles, but in other situations, that figure can drop to 60 miles. Kadota himself recently noted the following scenarios:

* Driving in bumper-to-bumper traffic at 15 mph in cold, wintry weather with the heater on? Expect a range of about 62 miles.
* Driving around 50 mph with the air conditioning on? Nissan says the range will fall to approximately 70 miles.
* In normal highway driving (i.e. 60-70 mph), the Leaf can travel approximately 105 miles, provided the climate controls are off.
* If you leave the heater and A/C off, and keep your speeds to 40 mph or less, the Leaf’s range can jump to roughly 138-140 miles.

Sound extreme? Admittedly, these are extremes. Not all drivers perpetually blast climate controls, drive flat-out down expressways, or sit endlessly in gridlocked traffic. The 100-mile range, which was based upon Nissan’s testing of the EPA’s LA-4 drive cycle, is believed to be a reasonable average.

What’s your commute like? Stuck in traffic? Blitzing down interstates? Can you hypermile your way to the workplace? Would the limited (and fluctuating) range of an EV mesh well with your driving habits, or will you keep shopping elsewhere?"

 

[EVDRIVER]

What wil impact range more than AC and heat is hills and your right foot. Knowing to back of on even a slight grade at highway speeds makes a hugh difference in consumption. I have been on the freeway and pushed the accel to go change form 55-60 on a very slight incline and you can watch the amps go from 60-70 to 110. In and EV that is quite a bit. If there is a gauge to show actual KW usage or amps in real time people will get a very good picture of how to curb their driving habits for more range. A meter that just shows more or less bars does not give the best picture. It is also interesting and practical to see real regen numbers in amps, etc rather than a representation. Perhaps this will be a display option.

 

[evnow]

* Driving in bumper-to-bumper traffic at 15 mph in cold, wintry weather with the heater on? Expect a range of about 62 miles.
* Driving around 50 mph with the air conditioning on? Nissan says the range will fall to approximately 70 miles.
* In normal highway driving (i.e. 60-70 mph), the Leaf can travel approximately 105 miles, provided the climate controls are off.
* If you leave the heater and A/C off, and keep your speeds to 40 mph or less, the Leaf’s range can jump to roughly 138-140 miles.

Very interesting. I've to add to this list. The one you highlighted is not covered here.

May be this will answer a lot of people's questions.

 

[EVDRIVER]

BEtween 60-70 is subjective because there is a big difference in consumption. I would like to see a realistic (not dyno or lab) for range with no accessories at a constant 70 MPH. Quoting speed ranges is ambiguous as there are big differences and it does not indicate the time at those speeds.

 

[Nubo]

I just can't see exceeding the LA4 range with steady highway cruise at 60mph, much less 70. But I wouldn't mind being proven wrong.

 

[evnow]

For comparison from the other thread where Andy posted this ...

As you see EV1 constant 60 mph range was higher than LA4.

This is for Leaf ...

 

[garygid]

Steady speed, smooth and level surface, high tire pressure, no headwind, no acceleration, no accessories, windows-up driving of a reasonably aerodynamic vehicle can take surprisingly little energy per mile, even when traveling at the higher freeway speeds.

Edit: Also, dry conditions, and neither too hot nor too cold.

 

[EVDRIVER]

Steady speed, smooth and level surface, high tire pressure, no headwind, no acceleration, no accessories, windows-up driving of a reasonably aerodynamic vehicle can take surprisingly little energy per mile, even when traveling at the higher freeway speeds.

The highway is called "fantasy land". Freeways have inclines, headwinds, sudden stops, passing.

 

[garygid]

Yes, such conditions are only rarely encountered in "real" driving.
If your range differs, it is usually for one of these reasons.

However, these conditions can easily be created, and than used when they do their outdoor "range" value testing.

But, like any other "standard" condition testing, use of the results should be done with a good measure of wisdom.

Oh, I forgot dry conditions, and not too hot or cold temperatures.

 

[evnow]

The highway is called "fantasy land". Freeways have inclines, headwinds, sudden stops, passing.

Ofcourse any close freeway close to urban area where you can cruise @ 60mph is a fantasy :lol:

We will get real free way tests only when Nissan lets journalists test unsupervised. That, I guess, will happen only closer to December.

 

[garygid]

Here, we often have to merge into slow-lane 65 and 70 mph traffic. 10 or 15 miles of 70 to 75 mph speeds are not uncommon. Of course, 10 to 30 mph are also common, but I try to avoid those.

 

[Nubo]

For comparison from the other thread where Andy posted this ...

As you see EV1 constant 60 mph range was higher than LA4.

This is for Leaf ...

Thanks, that's more encouraging than what I was thinking. Even some of the decidedly non-aerodynamic cars did ok at 60 vs. the LA4 test. I guess the extra drag at speed is offset by the losses inherent in stop and go taffic, even with regen.

 

[evnow]

I've updated the numbers above by adding the new highway scenario.

And here is some analysis. The one thing that seems to have most effect is the AC/Heater. That is what separates the above hundred from the below hundred. Interestingly nothing between 80 & 100, which I thought would be majority of scenarios. May be the above hundred ones will all get to be between 80 & 100 in real life. If you use heater/ac you take a big hit on the range.

 

[EVDRIVER]

Comparing data without knowing exactly how it was all derived may not be accurate. Driving 60 MPH is on the max side of speed where things start to drop off fast. Driving on real highways by a real driver and real road conditions at speeds of say 65-70 will most likely yield much different results. I wave driven the same length of road that is mostly "flat" and had a reduced range of 25% as a result of wind and a slight hill. Driving on a computer on flat ground is not the same as a real highway with a human at the wheel where there are many variations. If the Leaf can do 80 miles at 65 MPH by an average driver I would be really surprised. The only way to know is to actually drive one yourself, I know my range will be far higher than the "average" driver as I have much highway EV driving experience and I will be happy if I can get 70 mies at 70 MPH, time will tell

 

[evnow]

Comparing data without knowing exactly how it was all derived may not be accurate.

Hmmm .... I don't understand what that means, so i won't comment

ps : I'm not Nate Silver, but even I can make out that there is a high degree of correlation between AC on/off variable and the range.

pps : Are you basically saying, all standardized tests are useless ?

 

[EVDRIVER]

Comparing data without knowing exactly how it was all derived may not be accurate.

Hmmm .... I don't understand what that means, so i won't comment

ps : I'm not Nate Silver, but even I can make out that there is a high degree of correlation between AC on/off variable and the range.

pps : Are you basically saying, all standardized tests are useless ?

I'm not commenting on AC, that is clear. So every vehicle in the listed data had standardized highway tests? The bigger point, show me where highway conditions are like dynos and people drive like a computer. What I'm saying is that most people won't get those numbers and there is no better measure than real world driving. All of the EV miles I drove varied quite a bit on the same trips. Freeway conditions and wind will play into rage numbers quite a bit and although we all would love to believe we are going to get 100 miles range at 60 MPH it is most likely not going to happen for most, so I would caution people to be conservative on range estimates and then be potentially surprised/pleased.

 

[evnow]

... so I would caution people to be conservative on range estimates and then be potentially surprised/pleased.

I agree - and I've indicated as such in my post above. But it is still interesting in the given data set that such clear cut off is visible.

Ofcourse if we could drive & find out we wouldn't be doing all this analysis

 

[TimeHorse]

Hey EVNOW, thanks for the Twitter link; I really should start following you! (Done.)

Okay, so I see one very strange result in this:

Tests 8 and 9 are basically the same except for 9 is at 55 in the US and 8 is at 50 in Europe. The course is not there telling us how flat the course was or what the wind shear was, but 47 to 70 is night and day! At 70, I'm there and back again with 3 miles to spare; at 47, I get to work, and then die in Annandale, VA with 20 mi still to go. Yipes!

Also, it's quite strange this difference and the higher results when you consider maybe the problem is Metric vs. Imperial; certainly 160 km ~= 100 mi and I know I do about 54 km a day each way, or about 108 km, but if these numbers were being mixed up by units, I'd have expected the European results to be metric (UK excluded -- can't wait to see the LEAF on Top Gear!) but 47 km is like 30 mi, which would be even more incredible!

So how do you explain this? Well, my guess is the average speed is more varied for the European course and more stable for the U.S. course. Honestly, I'd have expected the opposite, but a varied course is going to pay a high penalty for wind shear for the times when it's well above 50 and get not as much relative benefit from the lower speeds.

That's why knowing the basics of the course is so handy, why the EPA numbers are more accurate: they show the amount of time spent idle, at 30 mph, at 50 mph, etc. This is more real-world than just running at a fixed speed.

That said, it really isn't real world to just hook up a dynomometer and measure. It won't take the direction of wind, the upward and downward slope of hills, or the effects of stop-and-go traffic. But as I've said before, each problem is separable. If you measure the draw of AC on a RAV 4 EV as requiring x additional power (which should, for the most part be proportional to temperature, not speed), then you can add that to your LEAF calculations as a constant term in the Power Curve. Climbing hills is proportional to the weight of the vehicle as well as speed: essentially you're providing potential energy by lifting the car as well as kinetic. I could be wrong, but I believe this leads to a linear additive factor that is based on slope and weight (or more specifically the rate of ascension times the mass of the vehicle -- power = mass times g times upward velocity component; g ~= 9.81 m/s**2). The additional wind shear caused by and in power requirement proportional to the square of velocity, would effective just be the car's air speed. Obviously a tail wind would help and a head wind would hinder (unless you put wings on your LEAF and intended to fly it once it reached 56 knots). Effectively, therefore, the way to apply the wind shear is by adjusting the v**2 term which means you have a constant, linear and squared wind shear component which could be negative if the wind is in your favor. Ideally, you'd want to have it drive down a wind tunnel, at a given air speed, and measure the power at negative wind, no wind, some wind, etc. and derive your calculations from that; just make sure if you measure at 30 mph you should have a tail wind going at -30mph to eliminate wind shear completely.

Of course, wind shear can and is typically modeled using CAD and if anything that should be the best measure of real-world conditions. It it was only possible to measure wind speed independent of ground speed...

In the end, I do want to know more about these figures. Do we have links to the original articles? If I could read those, maybe we could fine a couple in the no Heat/AC STP with a more or less constant speed to get the base curve.

 

[garygid]

Dynomometer testing can simulate hills by adding extra drag that is proportional to the slope times the car's weight. It already has to (should) simulate the car's mass by adjusting the drag proportional to the car's weight during acceleration.

It can also simulate wind loading, and any additional headwinds (or tailwinds), by adjusting the drag proportional to ... presumably velocity squared.

I have not seen a dynomometer loading profile for hills (if any) in the LA4 test.

 

[planet4ever]

Okay, so I see one very strange result in this:

Tests 8 and 9 are basically the same except for 9 is at 55 in the US and 8 is at 50 in Europe. The course is not there telling us how flat the course was or what the wind shear was, but 47 to 70 is night and day!

The European number was for a high speed road with roundabouts. While the average was 50 (80kph), my guess is that the target speed, when possible, might have been as high as 75 (120kph), and that there was a lot of slowing down for roundabout merges. This, and other heavy traffic numbers, suggest to me that the regen is not as effective as I might have hoped.