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LTLFTcomposite said:
evnow said:
Major CO2 reductions that are needed to save the planet (no hyperbole here) do not come about without any lifestyle changes.

CO2, schmee-O2, people aren't interested in making lifestyle changes to save the planet. Only solutions that enhance our lifestyles need apply.

Speaking on "saving the planet" George Carlin had something to say about that (of course):
http://gospelofreason.wordpress.com/2007/05/24/george-carlin-the-planet-is-fine/
 
mitch672 said:
LTLFTcomposite said:
evnow said:
Major CO2 reductions that are needed to save the planet (no hyperbole here) do not come about without any lifestyle changes.

CO2, schmee-O2, people aren't interested in making lifestyle changes to save the planet. Only solutions that enhance our lifestyles need apply.

Speaking on "saving the planet" George Carlin had something to say about that (of course):
http://gospelofreason.wordpress.com/2007/05/24/george-carlin-the-planet-is-fine/

http://www.universetoday.com/guide-to-space/earth/how-long-will-life-survive-on-earth/

So at best we've got half a billion years left.

"As the climate becomes warmer, the cycle of silicate rock weather speeds up, removing carbon dioxide from the atmosphere and sequestering it as calcium carbonate in the oceans. Without carbon dioxide, plants won't be able to survive, and everything relying on them dies too."

How ironic.
 
LTLFTcomposite said:
"As the climate becomes warmer, the cycle of silicate rock weather speeds up, removing carbon dioxide from the atmosphere and sequestering it as calcium carbonate in the oceans. Without carbon dioxide, plants won't be able to survive, and everything relying on them dies too."

How ironic.

Ok...you mean it'll be like the child that wants to walk to visit grandma? "silly child - of COURSE it's easy! All you have to do is dump a bunch of sponges into the Atlantic ocean and then you can walk from Maine to Wales."

Crushed rock can absorb CO2, and will eventually end up in the oceans to make new rock, we are reportedly putting 40 times more CO2 into the air than rock can remove naturally. MacKay suggests we could make a difference if we spread rock over all exposed land - who wants to start crushing rock?
 
Gonewild said:
I hear the Nissan Leaf will travel about 100 mile on the LA4 test. I drive about 38 mile to work one way on the freeway which is basically flat with no hills. Will the Leaf go to work and back at 65 mile per hour? I think once it is up to speed it would use less power then a lot of stops and starts to 45 or 50 mph. I looking forward to getting my car soon. I live in the Phoenix area and have my $99 buck in as soon as the email came in and it was processed with no problems.

I live in the Phoenix area too, and my commute is 70 miles roundtrip...I know I can go 65 (at the beginning of the trip, traffic has me going under 60) and make it (according to Nissan), so maybe if you slowed down to 60 for just a few miles, you would probably make it too.
 
EVDRIVER said:
evnow said:
Ofcource I should point out this is for Tesla Roadster, not Leaf.

A good way to calculate mileage wouldbe to use the wh/mile graph and use an assumption of usable 21 kwh energy in Leaf. You can get approximate range for any cycle that you want, including the newer cycle EPA uses (LA4 is the old EPA city cycle).

So @ 60mph, you need 250w/m - so you get a range of 84 miles. That is more than what I'd have guessed.

Having said that, everyone needs to assess how sustainable a lifestyle that needs 70 to 80 miles of commute a day really is. Major CO2 reductions that are needed to save the planet (no hyperbole here) do not come about without any lifestyle changes.

I would say closer to 70 with acceptable pack temps, no headwind or grades @ 65 mph. How do you get 250 wh/mile at 70? That's assuming the car consumes 250 at all speeds which is not accurate and making these comparisons to the Tesla is not a very accurate measure at highway speeds. That is an extremely low penalty to pay at highway speeds and the Leaf does not have astonishing aerodynamics. Since the Leaf has 19.2kwh to work with, even if it only consumed 250wh per mile that would be 76.8 miles best case. Remember, the car cycles to 80% DOD and it's quite sly to state a range based on 100% DOD and lowest possible consumption cycle.

Where did you see the DOD being 80%? I saw and read somewhere that it is going to be 90-10. And IF it is 80-20, is there a way to override it to make it 90-10? I'm leasing so battery life doesn't matter to me.
 
AndyH said:
Another look at energy use VS. speed - from the internal combustion world.

This chart is compiled from data collected by hundreds of VW diesel drivers that are part of tdiclub.com.
tdiclubchart.jpg


The first thing to point out is that it's 'upside down' compared with the Tesla watt hour per mile chart because it's a 'miles per unit of energy' chart instead of a 'unit of energy per mile' chart. Notice that the highest fuel economy for a range of different models (Jetta, Golf, Beetle, Passat have different colors) happens at 35mph?

While the absolute fuel economy - energy per mile - changes from a bit over 60 to 90 miles per gallon, the speed for highest economy (lowest energy use) happens at the same speed - regardless of vehicle size, drag, or weight (again - within this group of diesel powered VWs).

When an EV manufacturer says a car gets best range at 35 they're simply reflecting the laws of physics, not necessarily a misguided marketing department. It's common for electric scooter manufacturers, for example, to give a 'max range' number, and a 'max speed' number. The max range will happen at about 35 mph - and unless one has a downhill commute both ways :) they'll not get that same range at 55mph.

Just like with a gas car - if you need to get another 10 miles out of the 'tank' to make that fuel station, turn off the AC, slow down, and crank-up your hypermiling skillz. :D
Andy

Maybe those cars get their best mileage at 35, but I have a scangauge, and 42 mph is where I get the best mileage (low 50's). My car doesn't even shift yet at 35, so I'm surprised to hear that for diesel cars. I had a diesel rabbit and it obtained 55mpg at 60mph on the freeway. I did an economy run (contest) of 42 miles with it and obtained 82mpg blowing away ALL the other competitors. I remember passing a vette that was going about 12mph. :)
 
leaffan said:
Maybe those cars get their best mileage at 35, but I have a scangauge, and 42 mph is where I get the best mileage (low 50's). My car doesn't even shift yet at 35, so I'm surprised to hear that for diesel cars. I had a diesel rabbit and it obtained 55mpg at 60mph on the freeway. I did an economy run (contest) of 42 miles with it and obtained 82mpg blowing away ALL the other competitors. I remember passing a vette that was going about 12mph. :)

Absolutely! That particular chart was for Dub TDIs. Your car peaks a bit higher - the Tesla a bit lower. I expect there's good info in the curve even if we have to shift it around a bit.

What do you think our ScanGauges will do in the Leaf? :D

Andy
 
AndyH said:
leaffan said:
Maybe those cars get their best mileage at 35, but I have a scangauge, and 42 mph is where I get the best mileage (low 50's). My car doesn't even shift yet at 35, so I'm surprised to hear that for diesel cars. I had a diesel rabbit and it obtained 55mpg at 60mph on the freeway. I did an economy run (contest) of 42 miles with it and obtained 82mpg blowing away ALL the other competitors. I remember passing a vette that was going about 12mph. :)

Absolutely! That particular chart was for Dub TDIs. Your car peaks a bit higher - the Tesla a bit lower. I expect there's good info in the curve even if we have to shift it around a bit.

What do you think our ScanGauges will do in the Leaf? :D

Andy

I don't know if we'll be able to use them in an all electric car, so i was going to either put it in our other car, or let it go with my car when I sell it.
 
leaffan said:
I don't know if we'll be able to use them in an all electric car, so i was going to either put it in our other car, or let it go with my car when I sell it.

Good point...no OBDII port required since no emissions systems to track? Maybe Nissan will include it anyway as a system port. Something else to wait to find out. Thanks!
 
Although the Leaf could have an OBD II port (for diagnostic purposes), it won't be required for "emmisions" purposes, now would it. I do expect the car will have an I2C bus that is readable, so perhaps they will stay with an OBD 2 type connector (since it is a well recognized standard already), but it would probably be just for battery pack charge/discharge history downloading, and perhaps the torque/rpm of the motor could be read, and the SOC of the battery pack, etc. All of that may also be viewable on the built in display as well, who knows.
 
And, they could use the USB port to connect for data retrieval, diagnostics, error codes, etc.
That could make it more difficult for independent mechanics to diagnose the Leaf.
 
I doubt it's going to be too tough to crack every control system and data point in this car, right down to the EPS module.
 
garygid said:
EVD...,
What makes you think "cracking" the Leaf system will be easy?

Have you cracked the 2010 Prius?


Have been abe to get it done on Prius and others. Most CAN BUS and other related systems are not that difficult to access or control for practical use.
 
I believe the battery will be considered an emissions component. In any case, you can be assured the car will have an OBD2 port. It would be pointless for Nissan to make proprietary diagnostic tools for this vehicle, when a software update for the dealer's existing tool would do the job.
 
Bicster said:
I believe the battery will be considered an emissions component. In any case, you can be assured the car will have an OBD2 port. It would be pointless for Nissan to make proprietary diagnostic tools for this vehicle, when a software update for the dealer's existing tool would do the job.

Most likely. One nice feature on screen would be the ability to enter ones kWh for various charge times. Since the vehicle should know how many kWh it takes in during charging at these times that then could be translated to real time cost per minute or mile based on the way one is driving. Even if consumption is monitored post charger the numbers can be adjusted for charger efficiency.
 
Okay, back to the original question: what is the expected range of the Nissan Leaf. We know that under EPA*4* test LA4 that it has a total range of 100 mi, assuming ideal conditions. So, I'm going to repeat some of the math I did on Facebook but not all of it, so don't be frightened. :)

What we know is:

Range: 100 mi @ LA4
Battery Potential Energy: 24 kWh (86.4 MegaJoules)
Tires: P205/55R16 (205mm width, 55% ratio width to height, 16" rim -> 0.31595 meters wheel+tire radius*)
Average speed of LA4: 19.6 mph**
Maximum speed of LA4: 56.7 mph
Total distance of LA4: 7.45 mi

Since we know 7.45 mi is covered in LA4 and this represents the cycle under which 100 mi is achieved, that one LA4 represents 7.45% of the total driving range of the Nissan Leaf and thus 7.45% of the battery capacity:

Total Energy Used for LA4: 1.788 093 kWh or 6,437,136 Joules

Now we know what LA4 constitutes from this: http://www.epa.gov/nvfel/methods/uddscol.txt

Specifically, we have a table that gives us the speed used in 1 second intervals.***

The question is, how can we, if possible, use that to calculate what the expected range of the Leaf is under the more realistic US06*3*, HWFET*2* or EPA75?

I think our best bet is to try and match the Leaf to the Tesla curve. The trick is, I don't know what polynomial we're trying to fit, never mind the point where the slope becomes 0. Any thoughts?

I tried calculating the Moment of Inertia for the Nissan Leaf but I now think there was a flaw in the way I summed energies. So I think curve fitting is the best bet, since we know, in general, any electric car should follow the same curve Tesla uses, with a basic scaling factor. I'm sure it's more closely related to angular acceleration, perhaps angular acceleration * the moment of inertia to get the net energy transfer. If I knew the torque required for each speed, I could work backward by calculating the power over the 1-second interval from the torque and angular velocity, which in turn would give me the energy drain (1 Watt per Second = 1 Joule of Energy).

Anyway, I hope my Moment of Inertia calculations are very wrong since I came up with 50.5 mi range under US06, never mind 60.7 for HWFET, since I need a solid 67.

Of course, if Nissan would just publish these numbers... :roll:

Any thoughts? Thanks.

-------

* This is arrived at as follows: the 16" wheel rim diameter is halved and converted to meters to get the wheel radius: 16*0.0254/2 = 0.2032 m; add this to the tire height radius: 205mm = 0.205 m width * 55% or 0.55 = 0.11275 m. Sum the wheel radius and the tire height to get 0.31595 m total wheel-tire radius.

** Notice in the Tesla curve the optimal energy/speed ratio is around 19.6 mph!

*** The FTP, or EPA75, is LA4 + LA4[0:504], i.e. LA4 plus the first 505 seconds of LA4 repeated, which includes a second burst of 55+ mph driving in the test (the first burst peaks at second number 240 or exactly 4 minutes in). It replaces UDDS, which is the official name for LA4. EPA75 can be measured in 0.1 second intervals and therefore can give a finer grain of test data as well: http://www.epa.gov/nvfel/methods/ftp10hztable.txt

*2* HWFET or HFET is the Highway Fuel Economy [Test] Driving Schedule and also can be measured in 0.1 second intervals: http://www.epa.gov/nvfel/methods/hwy10hztable.txt

*3* US06 is known as the aggressive driving schedule, though it best matches my driving pattern because I do a lot of highway driving on my daily commute at hours where traffic is light: http://www.epa.gov/nvfel/methods/us06col.txt

*4* For all the EPA test driving suites, please visit: http://www.epa.gov/nvfel/testing/dynamometer.htm
 
drees said:
Yep, specifically look at the speed/range chart on their blog.

display_data.php


If you assume that the Tesla's ~240mi range is the same as the Leaf's 100mi range, that gives you an idea of what speeds you can travel for how far. Just divide the range number on the chart by 240 to get some real rough approximations.

Ah, but here's the rub: again, recall that that LA4's average speed is 19.6 mph, which on the Tesla chart comes to a maximum range of 410 mi. Scale that down to the Leaf: at 51 mph (my average speed) you're down to 260 mi, a drop of 63.4%, meaning you could expect the leaf's range to sink to 63.4 mi if you started driving 51, and then drove that for a distance of 63.4 you'd run out of fuel. Of course, I said Average speed, there's a lot of faster and a lot of slower actually under real circumstances. So clearly, even the Tesla doesn't go around boasting a range of 410 mi because they'd be laughed out of business, at the very best!

However, the Roadster efficiency and Range post does say that it achieves 244 mi under EPA "dynamometer". Technically, this could be HWFET or US06 or EPA75 or even SC03, the Air Conditioning supplement. But I agree, it's safe to assume they mean LA04 since most electrics look best in that light. So I agree, in principle, your numbers looks sound. I just wish I could get that curve as either a polynomial function or a spreadsheet of values to play with...
 
display_data.php


The power curve strikes me as the most useful graph. Not that I think I could map that to the Leaf directly, though Drees's first-level analysis is pretty good. Instead, I think the best thing to note here is what we know about the curve. At higher speeds, the drag increases as the square of the velocity. Thus, the power required and the energy used should, as speed increases, be dominated by the square of that speed. This is reinforced by the commentary that follows this curve. In fact, I think it's probably "good enough" to assume the power-velocity equation is of the form:

Code:
P(w) = a*w^2 + b*w + c

Where w is the angular velocity of the wheel (since we know the tire radius, we can easily convert between speed in mph and the wheel rotational velocity in radians per second by a factor of 1.414 907 422 060 45 hr-rad/mi-sec, exactly) and the Power is calculated in Watts. Here, a, b and c are unknowns constants, where a is some type of Moment of Inertia over Time in kg-m^2/s, b is some kind of Torque in N-m and c is some base power in Watts.

Of course, the specific units of a, b and c are irrelevant. The important thing here is that we have 3 unknowns we need to solve.

Again, we know what LA4 entails, we know it uses 6,437,136 of the 86.4 Joules of total battery capacity. We know it's 1370 or 22:50 seconds long (much of which is idle, hence the 19.6 mph average speed). Since we know the Energy and the time, we can compute the average power used but that doesn't really tell us anything AFAICT. However, the reverse should be straight-forward to calculate: if we know how much power is being used at a given 1-second interval we can calculate the energy by multiplying by 1 second.

So, in effect:

Code:
sum(P(w)[instant]*1sec)  = 6,437,136 Joules

This translates to:

Code:
a*sum(w^2) + b*sum(w) + c - 6,437,136 Joules = 0

Now, I can compute sum(w^2) and sum(w):

Code:
sum(w) = 37,949.797 930 052 3 rad/sec

Code:
sum(w^2) = 1,643,140.091 306 37 rad^2/sec^2

Hence:

Code:
37,949.797 930 052 3 rad^2/sec^2 * a + 37,949.797 930 052 3 rad/sec * b + c - 6,437,136 Joules = 0

It would also be safe to assume if no angular velocity is achieved, the power should be 0. However, I don't think from a mathematical point of view that this is a safe assumption in solving the polynomial. If we assume when w is 0 that the Energy must be 0, that would mean c must be equal to the LA4 energy. That seems kind of strange to base it on that so I have a feeling there is something more to the constant factor.

So what we're still left with is 1 equation and 3 unknowns! :( What I need are two more equation to solve this. Any ideas?
 
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