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Potential PHEV Test Procedure Changes

EPA/ARB/Industry Tier 3 Discussion 

Meeting

November 18, 2013 2PM

D. Good, Compliance Division
PHEV Test Procedures – Net Energy 

Change (NEC) Correction for CS Testing

In the Nov 6, 2013 meeting, Manufacturers, ARB & EPA agreed to accept the following:

For Greenhouse Gas Emissions:

• EPA Tier 3 NPRM proposed no change to manufacturers use of a NEC correction factor 

during CS testing, between +/-1 and +/-5 % of total fuel energy

– Prior EPA approval required per existing paragraph 40 CFR 600.116-12(b)(5). 

– Correct only CREE, CO2, fuel consumption/MPG; disregard any effect on criteria pollutants.

– Ref. 40 CFR 1066.501 as proposed in the Tier 3 rule

– Example NEC Correction from SAE J1711 Appendix C:

For Criteria Pollutants:

• As discussed in the Nov 6, 2013 EPA/ARB/Industry Webinar: 

– Expand NEC Tolerance from +/- 1% to +/-5% 

– Expanded Tolerance would apply to manufacturer, EPA & ARB testing

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• Alliance Tier 3 comments:

– Utility Factors should be applied to charge depleting criteria emissions

 EPA and ARB are not in favor of applying Utility Factors to CD emissions

– Manufacturers should be able to attest to charge depleting compliance 

– Vehicles must operate in a similar manner when operating at the same APU speed and load point in either 

charge sustaining or charge depleting mode.

• Alliance suggestion for Nov 18, 2013 meeting:

• EPA/CARB (“the Agencies”) expects manufacturers to provide the same emission performance in charge depleting mode as 

is provided in charge sustaining mode. In fact, it’s a regulatory requirement based on AECD regulations. The following text

is provided in an effort to clarify the Agencies position.

• Unless allowed by AECD exceptions, PHEV vehicle emission systems need to provide consistent and optimum emission 

performance regardless if it’s in charge sustaining (CS) or charge depletion (CD) modes. It is understandable that the APU 

would be at different operating conditions at the same vehicle speed and load point because of the expected power 

supplement provided by the battery system in CD mode. Therefore, the following comment is focused on the APU operating 

condition and not the vehicle driving condition. The Agencies expect, for the same APU operating condition, the emission 

control system (ECS) should perform the same (within engineering reason) between CS and CD. 

• Should a manufacturer were to violate the provisions above, the Agencies would consider the product to have an AECD and 

be under said scrutiny.

• With this understanding, manufacturers are allowed to declare via compliance statement that CS is the worst case mode. 

The manufacture would need to specifically attest the given test group doesn’t violate the provisions above.

• The mfr attests that CS is the worst mode.

• The mfr attests that for the same APU operating condition the emission control system should perform the same within 

engineering reason between CS and CD.

PHEV CD Test Procedures – Double Cold Start 

Penalty and Charge Depleting Criteria Emissions

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PHEV CD Test Procedures – Double Cold Start 

Penalty and CD Criteria Emissions (continued)

Option 1: ARB Modular Method:

g/mi = 0.43(UDDScold_worst /distancecold_worst) + 0.57(UDDShot_worst/distancehot_worst)

Where:

• UDDScold worst = worst CDcold or CScold (NMOG + NOx) emissions observed in an ARB 1-bag or EPA 2-bag UDDS

– (where worst CDcold includes the CD transition UDDS but not the UDDS following the CD transition UDDS)

• UDDShot worst = worst CDhot or worst CShot (NMOG + NOx) emissions observed in ARB 1-bag or EPA 2-bag UDDS

– (where CDhot includes the CD transition UDDS and one (or two?) UDDS cycles following the CD transition UDDS)

• The distances are those associated with each UDDS sample period

• Run the CD test to completion to generate Rcda, energy consumption, fuel economy, CO2 & GHG data

• Note: Use CS UDDScold emissions if CScold (NMOG + NOx) is worst than CDcold (NMOG + NOx) emissions

Use CS UDDShot emissions if CShot (NMOG + NOx) is worst than CDhot (NMOG + NOx) emissions

• Manufacturers may request EPA/ARB approval to handle double CD cold starts on a case-by-case basis

– For example, if the vehicle exceeds emission standards using the above Modular Method calculations and the 

CD cold start occurred within 60 seconds of the end of a UDDS, manufacturers could request approval to:

• use emissions from the first or second UDDS (if appropriate), or

• mathematically adjust the emission values from one of the UDDS cycles, or 

• Perform an additional CD test starting with the battery SOC similar to the point where the double cold 

start occurred (and use the results of that UDDScold in the Modular Method calculations). 

– Type G PHEVs (i.e., PHEVs capable of driving 10 mile minimum AER on multiple US06 cycles) would be allowed 

the following option:

– For cold start testing, allow battery SOC to be set such that the engine will start within 60 seconds of starting the 

UDDS cycle.

» Note: Within 60 seconds means the vehicle will be on the first hill of the UDDS with a speed of 

24.2 mph or less (similar to the type of driving when the double cold start occurred).

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PHEV CD Test Procedures – Double Cold Start 

Penalty and CD Criteria Emissions (continued)

Option 2: CD Averaging Method:

g/mi = ∑ (UDDSi emissions in grams) / ∑ distance of all UDDS cycles 

(including one transition UDDS)

• Doesn’t address the double cold start issue

• Is not a “worst case” approach

• Favors vehicles with longer electric range

• May understate in-use emissions due to the mild acceleration rates of the UDDS cycle

• EPA staff and ARB are not in favor of this approach

How should EPA/ARB assure emission compliance during CD tests?

– Require this type of (worst case) CD test data as part of certification ; or

– Not require worst case CD data but assure compliance via defeat device policy; or

– Require manufacturers to make a statement of compliance that CD tests comply with 

criteria pollutant emission standards (using Option 1 or Option 2 calculation method)

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• Proposed 

– Existing regulation (not Tier 3) establishes the In-use CREE standard by multiplying the 

certified CREE value of a given vehicle by 1.1

– PHEVs use the combined (55% city/45% highway) composite (utilitized CD and CS) 

CREE results for In-use standards and certification values---increased by 10%.

• Tier 3 comments from one manufacturer:

– PHEV CREE values are largely dependent upon CD range (Rcda) and the resulting Utility Factor.

– A small change in the Rcda can cause a major change in the in-use compliance level

• Manufacturers have very little experience in battery deterioration

• Suggest separate in-use standards for CD and CS operation 

• Options:

– Base CD PHEV In-use standard on the electric range (Rcda in SAE J1711)

• For example, Rcda of in-use vehicles could be no less than 90% of the Rcda of the 

certification vehicle

• EPA believes that a CS standard is also needed for all PHEVs (especially for PHEVs with 

shorter electric ranges)

– For example, the same standard as for conventional vehicles (CS CREE x 1.1) 

• Clarify regulations to point out that mfrs can voluntarily lower Rcda certification values 

(provided the lowered values are used for FE Label, CAFE & GHG calculations)

– Derive PHEV In-use standard using upstream emission calculation procedure 

– No change to existing regulations – Base PHEV In-use standard on 110% of the 

composite, combined CREE value used in the manufacturers GHG Model Year Report

– Other ideas?

PHEV Test Procedures – In Use CREE standards 

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Appendix

Previous Slides presented in 

November 6, 2013 Meeting
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Potential PHEV Test Procedure Changes

DRAFT – 11/1/2013

EPA/ARB/Industry Tier 3 Discussion 

Meeting

November 6, 2013 2PM

D. Good, Compliance Division
PHEV Test Procedures – Net Energy 

Change (NEC) Correction for CS Testing

• EPA Tier 3 NPRM proposed no change to manufacturers use of a NEC correction factor 

during CS testing, between +/-1 and +/-5 % of total fuel energy

– Prior EPA approval required per existing paragraph 40 CFR 600.116-12(b)(5). 

– Correct only CREE, CO2, fuel consumption/MPG; disregard any effect on criteria pollutants.

– Ref. 40 CFR 1066.501 as proposed in the Tier 3 rule

– Example NEC Correction from SAE J1711 Appendix C:

• Alliance comment:

– NEC correction factors, within limits in T3 proposal, should be allowed without EPA approval.

– Manufacturer should declare their intent to use NEC correction during the cert preview meeting.

• EPA sees no compelling need to revise 600.116-12(b)(5)

– Prior approval is needed to maintain level playing field for all manufacturers, etc.

• ARB/EPA/Industry discussion in Oct 30, 2013 Webinar: 

– Expand NEC Tolerance from +/- 1% to +5% / -1% (allow worst case manufacturer testing)

– Discuss EPA/ARB confirmatory testing

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• Tier 3 proposed not applying Utility Factors to Charge Depleting criteria emissions.

• Using UFs on criteria pollutants could mask high emission rates in extended blended 

mode operation

• Currently EPA assures criteria pollutant compliance on CD tests through the defeat 

device policy 

• Alliance comment:

– Utility Factors should be applied to charge depleting criteria emissions

– Manufacturers should be able to attest to charge depleting compliance

– Vehicles must operate in a similar manner when operating at the same APU speed 

and load point in either charge sustaining or charge depleting mode.

• ARB Method – Stop/Start:

• Stop the CD test as soon as the engine starts and soak 10 minutes

• Resume CD test with a new UDDS cycle

• Engine should start soon after beginning UDDS capturing single cold start

• Apply standard PHEV mass emissions calculation to determine certification compliance:

g/mi = 0.43(UDDScold /distancecold) + 0.57(UDDShot /distancehot)

PHEV CD Test Procedures – Double Cold Start 

Penalty and Charge Depleting Criteria Emissions

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PHEV CD Test Procedures – Double Cold Start 

Penalty and CD Criteria Emissions (continued)

Modular Method:

• This approach addresses the double cold start penalty that could only be 

experienced with a PHEV if conditions were just right.

• This approach may not address a blended mode PHEV that cycles the engine 

throughout CD testing enough to exhibit multiple cold starts. 

g/mi = 0.43(UDDScold_worst /distancecold_worst) + 0.57(UDDShot_worst/distancehot_worst)

• The UDDScd is the single worst UDDS (ARB 1-bag UDDS),(EPA 2-bag UDDS) 

• The UDDScs is the CS hot-start UDDS (Bag 2 of the ARB Charge sustaining test or Bags 

3 and 4 of the EPA Charge sustaining test) 

• The distances are those associated with each UDDS sample period

• Pro: Eliminates double cold possibility, uses existing test data, can be used to check that 

Fuel economy tests are “meeting standard”

• Con: Provision required to address blended mode PHEVs (such as limiting the 

substitution of CS hot bag to only one CD bag), effect are unknown (this method had not 

been applied to any data, yet) 

How should EPA/ARB assure emission compliance during CD tests?

– Require this type of (worst case) CD test data as part of certification ; or

– Not require worst case CD data but assure compliance via defeat device policy; or

– Require manufacturers to make a statement of compliance that CD tests comply with criteria 

pollutant emission standards

– Also require assurance that vehicles operate in a similar manner when operating at the same 

APU speed and load point in either charge sustaining or charge depleting mode

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• Proposed 

– Existing regulation (not Tier 3) establishes the In-use CREE standard by multiplying the certified CREE 

value of a given vehicle by 1.1

– PHEVs use the combined (55% city/45% highway) composite (utilitized CD and CS) CREE results for 

In-use standards and certification values---increased by 10%. 

• Tier 3 comments from one manufacturer:

– PHEV CREE values are largely dependent upon CD range (Rcda) and the resulting Utility Factor.

– A small change in the Rcda can cause a major change in the in-use compliance level

• Manufacturers have very little experience in battery deterioration

• Suggest separate in-use standards for CD and CS operation 

• EPA Concerns:

– Completely separating CD and CS modes for PHEVs would lead to no CD range degradation 

consequences, since the CREE cert level during CD is usually zero and is independent of range when 

examined independently of CS

– The In-use liability is largely due to the “zero” upstream credit allowed for electricity

• Any electric range lost is essentially replacing “zero” with XXX g/mi

• Assigning some value to upstream for In-use would lessen the impact of battery degradation and retain the 

upstream “credit” as proposed in the original GHG rule

• Options:

– Base PHEV In-use standard on the electric range (Rcda in SAE J1711)

• For example, Rcda of in-use vehicles could be no less than 90% of the Rcda of the certification vehicle

– Derive PHEV In-use standard using upstream emission calculation procedure (manufacturer prop.)

– No change to existing regulations – Base PHEV In-use standard on 110% of the composite, combined 

CREE value used in the manufacturers greenhouse gas Model Year Report

– Other ideas?

PHEV Test Procedures – In Use CREE standards 

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