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§1065.510 Engine mapping.

(g) Mapping engines with an electric hybrid systems. Map engines that include electric hybrid 

systems as described in this paragraph (g). Do not use this procedure for engines used in hybrid 

vehicles where the hybrid system is certified as part of the vehicle rather than the engine. You 

may ask to apply these provisions to other types of hybrid engines, consistent with good 

engineering judgment. Follow the steps for mapping a variable-speed engine as given in 

paragraph (b) of this section. Note that you are generally required to generate two separate 

engine maps: one with the hybrid system active, and one with it inactive. Apply the provisions 

of paragraph (b)(5) of this section as follows:

(1) This paragraph (g)(1) specifies how to generate a map with the hybrid system inactive. Note 

that this is generally necessary for engines subject to steady-state duty cycles (i.e., discrete-mode 

or ramped-modal). Operate the engine at warm idle speed until the renewable energy storage 

system (RESS) is depleted. Once the RESS is depleted, perform an engine map as specified in 

paragraph (b)(5) of this section. Ensure that instantaneous power from the RESS remains less 

than 2 % of the instantaneous measured power from the engine at all engine speeds. 

(2) This paragraph (g)(2) specifies how to generate a map with the hybrid system active using a 

nominally continuous method or a discrete method. You may use either of the following 

methods to generate a map with the hybrid system active:

(i) You may perform an engine map by using a series of continuous sweeps of narrow speed 

ranges. Note that the purpose of this mapping approach is to determine the maximum torque 

available at each speed such as might occur during transient operation with a fully charged 

RESS. Begin by fully charging the RESS. Perform the sweep as specified in paragraph (b)(5) of 

this section, but stop the ramp to charge the RESS when the power measured from the RESS 

drops below maximum expected RESS power by more than 2 % of total system power

(including engine and RESS power). Unless good engineering judgment indicates otherwise, 

assume that the maximum expected RESS power is equal to the measured RESS power at the 

start of the ramp. (Note that this assumption is not valid where the RESS is torque limited.) 

Calculate total system power as a 3 second moving average of total system power. For example,

if the 3 second moving average of total engine-RESS power is 200 kW and the power from the 

RESS at the beginning of the ramp is 50 kW, once the power from the RESS reaches 46 kW,

stop the ramp to charge the RESS. After each charging event, stabilize the engine for 15 seconds

at the speed at which you ended the previous segment with operator demand set to maximum 

before continuing the ramp from that speed. Repeat the cycle of charging, mapping, and 

recharging until you have completed the engine map. You may shutdown the system or include 

other operation between segments to be consistent with the intent of this paragraph(g)(2)(i). For 

example, for systems in which continuous charging and discharging can overheat batteries to an 

extent that affects performance, you may operate the engine at zero power from the RESS for 

enough time after the system is recharged to allow the batteries to cool. Use good engineering 

judgment to smooth the torque curve to eliminate discontinuities between map intervals.

(ii) You may perform an engine map by using discrete speeds. Select map setpoints at intervals 

defined by the ranges of engine speed being mapped. From 95 % of warm idle speed to 90 % of 

the manufacturer declared rated speed select setpoints that are 7.5 % of manufacture declared 
rated speed apart. From 90 % to 110 % of manufacturer declared rated speed select setpoints 

that are 2.5 % of manufacture declared rated speed apart. From 90 % of manufacture declared 

rated speed to the highest speed above maximum power at which 50 % of maximum power 

occurs select setpoints that are 7.5 % of manufacture declared rated speed apart. We refer to this 

50 % speed as the check point speed as described in paragraph (b)(5)(iii) of this section. At each 

setpoint, stabilize speed and target torque at about 70 % of peak torque of the non-hybrid assisted 

engine. Make sure the engine is fully warmed up and the RESS state of charge is within the 

normal operating range. Snap the throttle to maximum and stabilize the engine for at least 10 

seconds and record the mean feedback speed and torque of the last (4 to 6) seconds. Use linear 

interpolation to determine intermediate speeds and torques. Use this series of speeds and torques 

to generate the power map as described in paragraph (e) of this section.

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