AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: Response to EPA FOIA Request

Thu Jan 20, 2011 8:38 pm

evnow wrote:
AndyH wrote:I haven't seen a current J1634 test procedure document but have a copy of the older spec, which required a continuous run thru multiple test cycles until the battery is depleted.
See the EPA_test_procedure_for_EVs-PHEVs-1-13-2011.pdf that OP links to. It gives exactly how the test was done (I've that text in the first page) - they run till the car can no longer keep pace. Then recharge to figure out the energu consumption from the wall. That is what they use to give kwh/100 mile stat.
Right - read that. The actual J.... spec outlines the gory details of vehicle weight, that tires can be shaved, tire pressure, etc. I'd like to know exactly why the weight difference between 'curb' and 'as tested' and haven't found it yet.

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: Response to EPA FOIA Request

Thu Jan 20, 2011 9:22 pm

AndyH wrote:Right - read that. The actual J.... spec outlines the gory details of vehicle weight, that tires can be shaved, tire pressure, etc. I'd like to know exactly why the weight difference between 'curb' and 'as tested' and haven't found it yet.
I was wondering what you were saying ... got it.

Might they be using the old test doc still ?

Next year they will be making big changes as we know, and perhaps thats when they start using the new tests.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

Smidge204
Posts: 940
Joined: Wed Nov 24, 2010 1:42 pm

Re: Response to EPA FOIA Request

Fri Jan 21, 2011 3:55 am

Isn't the curb weight something like 3300 pounds? So an additional ~400 pounds could be two or three adults plus a bit of cargo.

While I understand where the 0.7 multiplier comes from, I'm not convinced it's truly appropriate for EVs. (Docs here - PDF). It is a very broad brush they paint with.

AndyH wrote:Both cars use 'flat' laminated lithium ion cells, and both are a LiMn variant.

Intro to Volt Battery from GM:
http://media.gm.com/content/dam/Media/m ... ry_101.pdf

The Leaf service manual identifies the motor in this way:
• The traction motor contains a compact, lightweight, high output, high efficiency “Interior Permanent Magnet Synchronous Motor (IPMSM)”.
• The traction motor inverter is a device which converts DC power from the Li-ion battery to AC power, and drives the traction motor. Because the AC power frequency and voltage can be varied when the DC power is converted to AC power, it provides control performance with a high degree of freedom.
Okay. Just trying to think what might account for the small difference in density. Perhaps the Volt's thermal management adds just enough weight to bring down the entire pack's specific energy by that 2%. Also, that description of the Leaf's motor still does not equate to "DC Permanent Magnet, brushless." That's a very different animal.

=Smidge=

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: Response to EPA FOIA Request

Fri Jan 21, 2011 4:56 pm

AndyH wrote:Right - read that. The actual J1634 spec outlines the gory details of vehicle weight, that tires can be shaved, tire pressure, etc. I'd like to know exactly why the weight difference between 'curb' and 'as tested' and haven't found it yet.
Here's a copy of the 1999 J1634 test procedure: [edit...SAE docs automatically expire after 5 years - this doc is legally dead. But it's very close to the last few generations of J1634 and is likely to be very close to the current version. /edit]
http://wenku.baidu.com/view/882edf51ad0 ... 84060.html

4.1.4 The vehicle shall be tested at loaded vehicle weight - curb weight plus 136kg (300 lbs).

Here's an implementation of the test as conducted by Electric Transportation Applications in 1997, and appears to be the method used (with modifications) for the 2000-era EVs:
http://avt.inel.gov/pdf/fsev/eva/etatp3r2.pdf
Smidge204 wrote: Also, that description of the Leaf's motor still does not equate to "DC Permanent Magnet, brushless." That's a very different animal.
Agreed. Looks like there's still plenty for the EPA to learn about EVs. ;)
Last edited by AndyH on Sat Jan 22, 2011 6:37 am, edited 1 time in total.

SanDust
Posts: 1363
Joined: Fri Aug 06, 2010 10:54 am

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 12:21 am

Smidge204 wrote:Quick backstory: After a disagreement with another forum member over the testing procedures used, I decided to go right to the source and get a real answer. The punchline is we were both right and yet both wrong - it seems they used the J1634 test method but applied all the corrections from the 5-Cycle test to the result.
Not to kill your backstory but it seems overly revisionist. In the context of how easy it would be for the EPA to measure the kWh used in charging the Leaf, I wrote: "J1634 requires that the car be run through test cycles until the traction battery voltage falls below the minimum specified by the manufacturer or the car can no longer meet the speed requirements of the test. There isn't any extrapolation. Run till death." You replied to this as follows:

"If the EPA used the SAE J1634 test standard you might have had a point. They also would have gotten different numbers. Sadly, they don't use that test so you're wasting your time. ... Grab yourself a nice big mug of hot cocoa and have a read before commenting on the test procedures again."

Just one simple question was at issue: Did the EPA use J1634 to test the Leaf. You said no. I said yes. There was no discussion of anything else.

Moreover, you were actually wrong on two points not just one. You were wrong that the EPA didn't use J1634. And you were wrong in claiming that had it used J1634 the numbers would have been different than had it used the non-existent 5-Cycle test for EVs. As you now recognize, and what was obvious and well known to many at the time, is that the adjustment to the 2-Cycle test is designed to yield the same number as the 5-Cycle test (which is not BTW the same thing as saying the EPA "applied all the corrections from the 5-Cycle test", whatever that means.)

User avatar
evnow
Moderator
Posts: 11480
Joined: Thu Apr 22, 2010 11:41 am
Delivery Date: 25 Feb 2011
Leaf Number: 303
Location: Seattle, WA

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 12:39 am

SanDust wrote: Just one simple question was at issue: Did the EPA use J1634 to test the Leaf. You said no. I said yes. There was no discussion of anything else.
Not so. There were many other things said.

http://www.mynissanleaf.com/posting.php ... =4&p=43998
As for thinking the EPA numbers don't reflect reality, it doesn't matter if u agree with the EPA range number, all u have to accept is that the EPA can measure the current from the wall. If the EPA tests found the range of the Leaf to be 146 miles then it would find that the Leaf uses 17 kWh to go 100 miles. The battery capacity used would still be 21.6 kWh. If u don't think the EPA can measure current then ur just choosing to believe the EPA doesn't have the competence of a high school science team. Watt meters are not exotic pieces of equipment and measuring the amount of current that comes out of an outlet isn't exactly a tough assignment.
Turns out they used fudged range to calculate kwh/100 miles, for eg.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

SanDust
Posts: 1363
Joined: Fri Aug 06, 2010 10:54 am

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 12:40 am

Smidge204 wrote:Isn't the curb weight something like 3300 pounds? So an additional ~400 pounds could be two or three adults plus a bit of cargo.
The EPA uses Equivalent Test Weight which is based on the curb weight of the vehicle plus the carrying capacity of the vehicle, otherwise known as Loaded Vehicle Weight. http://edocket.access.gpo.gov/cfr_2008/ ... 129-00.pdf

SanDust
Posts: 1363
Joined: Fri Aug 06, 2010 10:54 am

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 1:07 am

evnow wrote:Turns out they used fudged range to calculate kwh/100 miles, for eg.
I've tried to explain this to you several times. Think about it. If you're trying to determine how many kWh you're putting into the battery it doesn't matter what the kWh/100 mile figure is. The EPA drains the battery. Then it charges the battery and measures how much power has delivered from the wall. It's just simple counting and it's all that matters. The range and the kWh/100 miles only comes into play because you're trying to find how many kWh are in one charge.

Maybe numbers will help. If the EPA finds the Leaf uses 34 kWh per 100 miles and the range is 73 miles, then one charge taking you those 73 miles would equal (73/100) X 36 = 24.82 kWh at the wall. If the EPA didn't use the deflator it would find the Leaf uses 23.8 kWh (.7 X 34) per 100 miles and the range to be 104 miles. In this case the one charge taking you those 104 miles would equal 104/100 X 24 = 24.96 (difference due to rounding).

Not sure how else to explain this. The equation is (Range/100 miles) = (kWh needed to fill/kWh needed for 100 miles). It's just a simple proportion yielding the same result no matter what the kWh/100 mile number is because as the the range changes so does the the kWh needed for 100 miles.

AndyH
Posts: 6388
Joined: Fri Apr 23, 2010 3:43 pm
Location: San Antonio

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 4:19 am

SanDust wrote:
evnow wrote:Turns out they used fudged range to calculate kwh/100 miles, for eg.
I've tried to explain this to you several times. Think about it. If you're trying to determine how many kWh you're putting into the battery it doesn't matter what the kWh/100 mile figure is. The EPA drains the battery. Then it charges the battery and measures how much power has delivered from the wall. It's just simple counting and it's all that matters. The range and the kWh/100 miles only comes into play because you're trying to find how many kWh are in one charge.
Yes - the test was 'run until empty' - not the short form. Yes - the EPA knows how to measure how much energy it takes to recharge the pack. You're in fine shape so far.

But then the EPA discounts 30% of the MEASURED range as an adjustment factor to arrive at the 'window sticker' number.

So yes - you're right, EVNOW is right, and Smidge is right.

DarkStar
Posts: 2066
Joined: Sat Jul 17, 2010 10:06 am
Delivery Date: 25 Mar 2011
Leaf Number: 568
Location: Hillsboro, Oregon, USA
Contact: Website

Re: Response to EPA FOIA Request

Sat Jan 22, 2011 10:44 am

AndyH wrote:But then the EPA discounts 30% of the MEASURED range as an adjustment factor to arrive at the 'window sticker' number.
So the EPA got over 100 miles on a charge?
Mikiko (2011 Nissan LEAF ETEC) Status:
Reserved: 04/20/10 | Ordered: 10/01/10 | EV Project Blink Installed: 03/22/11 | Delivered: 03/25/11 | VIN: 568

Oregon Electric Vehicle Association | Electric Auto Association

Return to “News & Main LEAF Discussion”