Response to EPA FOIA Request

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Smidge204

Well-known member
Joined
Nov 24, 2010
Messages
940
This morning I got my response to a FOIA request I sent to the EPA just before Christmas! Wasn't quite sure what to expect so I can't say I'm disappointed (and they didn't charge me anything since they said the total cost was under $14 - bonus!)

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.

So I asked for some specifics on both the LEAF and Volt tests, including weight, driving mode and exact procedure documentation.

Documents here: http://www.smidgeindustriesltd.com/leaf/EPA/

Full disclosure: I am not releasing the letter they sent, since it contains personal information and nothing about the Leaf/Volt. Also, the spreadsheet is combined version of two separate files they sent (one for each vehicle) - I figured combining them would help for comparison. Also tweaked the formatting (cell wrapping, font change) but otherwise contents are exactly as received.
=Smidge=
 
It's not the body size that defines the class of car. It's the interior space.

So typical American car. Huge on the outside, little room for the passengers (4 instead of 5) and the volt ends up a compact.

From wikipedia:
"New "official" size designations in the U.S. were introduced by the EPA, which defined market segments by passenger and cargo space."
 
mwalsh said:
Nice stuff. One thing that popped right out at me was the classification of the LEAF as a mid-size and the Volt as a compact. Not that I think it makes any difference, but what is up with that anyway?
The vehicle size is determined by the "Interior volume index" (in cubic feet). A compact car has between 100 and 109.9 cubic feet, and a mid-size car has between 110 and 119.9 cubic feet.
 
Crappy economy numbers from the Volt. I'd love to see the Prius numbers along side. ;)

I've an older copy of J1634 and am not surprised by the test cycle performed but SAE specs automatically die after 5 years and I hadn't heard that J1634 had been revised or how - thank you for confirming that this is still the process used!

I don't like the revised EPA numbers though. While the new 70% number better reflects the 'economy' of a typical American car being driven by a typical driver and their jackrabbit starts to 10mph over the speed limit with the AC blasting, :D I find that the old EPA number very accurately mirrors the economy from a reasonably conscious driver.

For example - my '97 VW Passat Diesel (with 397,000 miles on the clock) gives me 38-41 around town and 47-50 on the highway (and yes - the AC is running!). Here's the EPA economy comparison:

Code:
             City    Highway   Combined
Actual:     39       48
Old:         38       47            42
New:        32       42            36

While it's unfortunate that the EPA takes the Leaf down to 73 miles range, I think that folks transitioning from other EVs or the Prius (or are reasonably conscious drivers) will get much closer to Nissan's reported 111 city miles and 94-97 miles highway.

Very nice job Smidge!
 
Clearly you have never driven with my wife!

AndyH said:
I don't like the revised EPA numbers though. While the new 70% number better reflects the 'economy' of a typical American car being driven by a typical driver and their jackrabbit starts to 10mph over the speed limit with the AC blasting, :D I find that the old EPA number very accurately mirrors the economy from a reasonably conscious driver.
 
AndyH said:
While it's unfortunate that the EPA takes the Leaf down to 73 miles range, I think that folks transitioning from other EVs or the Prius (or are reasonably conscious drivers) will get much closer to Nissan's reported 111 city miles and 94-97 miles highway.
Except that 73 miles appears to be fairly representative of the range that you'll have if you drive on the highway at 70mph with the AC running on a warm day... I know that in my Prius in those conditions I get will high 40s to 50 mpg in that scenario. I've only broken 50 mpg a couple times on a whole tank - worst tanks were around 40 mpg but lifetime average is 46 mpg - or just about what the EPA says we'll get.
 
drees said:
Except that 73 miles appears to be fairly representative of the range that you'll have if you drive on the highway at 70mph with the AC running on a warm day...
But that is not what EPA is saying it is. EPA says it is a "combined" city/highway cycle - with some use of AC/heater.
 
Here is the relevent test procedure from the docs on Leaf. No surprises on how they tested for city & highway. But they applied a "maximum of 30%" i.e. they multiplied by 0.7 whatever they got out of the actual dynamometer test. So, on the dynamometer - the combined city/highway test would be about 100. In other words Leaf has a range of more than 100 miles on LA04.

1. Electric Vehicle Test Procedure - In general, EPA testing follows SAE Recommended Practice
J1634 "Electric Vehicle Energy Consumption and Range Test Procedure," which (as the title implies) is
basically a dynamometer test procedure used to measure the energy consumption and driving range of
an electric vehicle.

Electric Vehicle - City Test Procedure Summary - Following SAE J1634 Recommended Practice, the
battery is fully charged, the vehicle is parked over night, and then the following day the vehicle driven
over successive city cycles until the battery becomes discharged (and the vehicle can no longer follow the
city driving cycle). After running the successive city cycles, the battery is recharged from a normal AC
source and the energy consumption of the vehicle is determined (in kW-hr/mile or kW-hr/100 miles) by
dividing the kilowatt-hours of energy to recharge the battery by the miles traveled by the vehicle. To
calculate the energy consumption in units of mpge (miles/gallon equivalent) we use a conversion factor of
33.7 kilowatt-hours of electricity per gallon of gasoline (which is basically a measure of the energy in
gasoline (in BTUs) converted to electricity). The city driving range is determined from the number of miles
driven over the city cycle until the vehicle can no longer keep up with the driving cycle.

Electric Vehicle – Highway Test Procedure Summary - The same test SAE J1634 procedure outlined
above, is used determine the highway energy consumption and the highway driving range (except the
vehicle is operated over successive highway cycles) .

Electric Vehicle - Adjustment Procedure used to Derive City & Highway FE Label (Window Sticker)
Estimates - EPA regulations require the city and highway energy consumption and driving range values
listed on the FE Label (window sticker) to be adjusted to more accurately reflect the energy consumption
and driving range that customers can expect to achieve in the real world. For EVs, EPA currently uses
the derived 5-cycle adjustment method described in 40 CFR 600.210-08(a)(2)(i) and (a)(2(ii), capped at a
maximum adjustment of 30% (i.e. multiply unadjusted values by 0.7).
 
Finally getting a chance to actually review the spreadsheet...


"FE Conventional Fuels" (Cols. L, M, N)
Leaf: 106 city, 92 Hwy, 99 Combined
Volt: 35 City, 40 Hwy, 37 Combined

"Unadj. FE" (Cols. O, P, Q)
Leaf: 151.5 City, 131.3 Hwy, 141.69 combined (MPGe)
Volt: 45.41 City, 52.75 Hwy, 48.44 Combined

"This is what we actually got from the tests." :D


"Trans Desc" (Col. V)
Leaf: Automatic
Volt: Continuously Variable

"Trans Lockup" (Col. Y)
Leaf: Y
Volt: N

These two make no sense. Considering they also reported the Leaf as having a "DC Permanent Magnet" (see below) are they sure they actually tested a Leaf at all?


"Range 1 - Model Type Driving Range - Conventional Fuel" (Col. AE)
Leaf: 73
Volt: 344

I usually get about 360 miles out of my '04 Jetta before fillup. :D


"Fuel usage Description - Conventional Fuel" (Col. AG)
Leaf: Battery Electric
Volt: Gasoline (Premium Unleaded Required)

So the Volt needs premium grade gas. That makes cost effectiveness much more sensitive to economy. Poor Volt drivers!


"Calc Approach Desc" (Col. BN)
Leaf: "Derived 5-cycle label"
Volt: "Vehicle Specific 5-cycle label"

In other words, the Volt got special treatment while the Leaf got the generic "we don't know what else to do" treatment. :roll:


"Batt Specific Energy (Watt-hr/kg)" (Col. CL)
Leaf: 82.8
Volt: 80

Interesting.. anyone know what form factor the Volt uses for its cells? To they use the cylindrical cans?


"Motor Gen Type Desc" (Col. CY)
Leaf: DC Permanent Magnet, brushless
Volt: Other (3 Phase Asynchronous)

That's not right, is it?
=Smidge=
 
Smidge204 said:
"FE Conventional Fuels" (Cols. L, M, N)
Leaf: 106 city, 92 Hwy, 99 Combined
Volt: 35 City, 40 Hwy, 37 Combined

"Unadj. FE" (Cols. O, P, Q)
Leaf: 151.5 City, 131.3 Hwy, 141.69 combined (MPGe)
Volt: 45.41 City, 52.75 Hwy, 48.44 Combined

"This is what we actually got from the tests." :D

So, I've to wonder whether they used more than 30% fudge factor. Here it looks like 40%.
 
evnow said:
So, I've to wonder whether they used more than 30% fudge factor. Here it looks like 40%.

Unadjusted = 141.69
Adjustment: 0.70
Final: 99.183

Round it off to 99 and that's the MPGe on the EPA label.
=Smidge=
 
Smidge204 said:
Unadjusted = 141.69
Adjustment: 0.70
Final: 99.183

Round it off to 99 and that's the MPGe on the EPA label.
=Smidge=
That's right. I was incorrectly looking at 99 as the base.
 
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/microsites/product/volt/docs/battery_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.
 
Smidge204 said:
"Trans Desc" (Col. V)
Leaf: Automatic
Volt: Continuously Variable

"Trans Lockup" (Col. Y)
Leaf: Y
Volt: N

These two make no sense.
I'm not sure why you say that. In a general sense, couldn't you say the LEAF has an automatic transmission (no clutch pedal) that can be (always is) locked into a single gear with no clutch in the transmission? You certainly can't make that second statement about the Volt - which has two clutches and a brake in the transmission, if I remember correctly - and the Volt's transmission is a CVT in the same sense as the Prius's (i.e. electrical, not mechanical).
 
Here is the city/hwy break up of range.

FUEL CONSUMPTION(kWhr/100mile):32(CITY) 37(HWY) 34(Comb.),RANGE(mile):77(CITY) 67(HWY) 73(Comb.),BATTERY CHARGING TIME(Hour):7hours at 240V

So, considering 30% adjustment, the unadjusted range is

City : 110 miles.
Hwy : 95.7 miles.

All this with 3,700 lb (i.e. they have loaded Leaf with quite a bit of luggage).
 
evnow said:
Here is the city/hwy break up of range.

FUEL CONSUMPTION(kWhr/100mile):32(CITY) 37(HWY) 34(Comb.),RANGE(mile):77(CITY) 67(HWY) 73(Comb.),BATTERY CHARGING TIME(Hour):7hours at 240V

So, considering 30% adjustment, the unadjusted range is

City : 110 miles.
Hwy : 95.7 miles.

All this with 3,700 lb (i.e. they have loaded Leaf with quite a bit of luggage).
Nissan reported an 'as tested' weight of 3750 lbs. The Euro press kit says curb weight between 3325 and 3509lbs. Someone else posted numbers that suggested the SL is 3375lbs empty. Maybe testing simulates 2 small occupants (~120lbs) or, well, a more 'typical' American and his/her briefcase/suitcase? I don't recall reading in the old J1634 that the car had to have weight added to simulate passengers or cargo. Dunno. :?

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. Based on this DoE paper from June 2010, the new J1634 test might not include 'run to empty' but rather a much shorter cycle. The industry is (was?) looking for a shortcut. FWIW.
http://www1.eere.energy.gov/vehicle...view_2010/veh_sys_sim/vss027_duoba_2010_o.pdf
 
AndyH said:
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.
 
Here is another interesting set.

City Unadj FE - Conventional Fuel : 151.5 MPGe
Hwy Unadj FE - Conventional Fuel : 131.3 MPGe

33.7 kilowatt-hours of electricity per gallon of gasoline

So,

City : 4.5 Miles/kwh
Hwy : 3.9 Miles/kwh

Remeber these are wall to wheels.

From earlier

City : 110 miles.
Hwy : 95.7 miles

So, the amount of energy used to charge, we get 2 figures, in close agreement.

City : 24.47 kwh
Hwy : 24.56 kwh

One thing to note is - we don't know whether the test ended soon after the turtle mode started. If the car couldn't keep the required speed in turtle mode, they would have stopped the test.
 
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