Historical
SAE J 2841-2009 (SAE J2841-2009)
Utility Factor Definitions for Plug-In Hybrid Electric Vehicles Using 2001 U.S. DOT National Household Travel Survey Data
This SAE Information Report establishes a 'Utility Factor' (UF) curve and the method of generating this curve. The UF is used when combining test results from battery charge-depleting and charge-sustaining modes of a Plug-in Hybrid Electric Vehicle (PHEV). This document will define the UF curve(s) by using 2001 United States Department of Transportation (DOT) 'National Household Travel Survey' data. The input is daily vehicle miles traveled, and the UF curve output is a percentage fraction that is applied to the charge-depleting mode results. In use, the total fuel and energy consumption rates of a PHEV vary, depending upon daily driving distances. For PHEVs, the baseline assumption using the UF is that operation starts fully charged and begins in battery charge-depleting mode. Eventually, the vehicle must change to a charge-sustaining mode. The vehicle miles traveled between charge events determine how much of the driving is performed in each of the two fundamental modes. A second assumption is that charging occurs every day after the day's driving is complete. In the absence of PHEV driver behavior data, the two unknown driver behavior issues of 1) how often charging occurs during the day ('opportunity charging') and 2) how often a driver will forget to charge, is assumed to be an equally offsetting, thus the baseline assumes one charge per day of operation. For a given set of recorded in-use driving data, an equation describing the portion of driving in each mode is defined on the basis of daily vehicle miles traveled. Driving statistics from the National Household Travel Survey are used as inputs to the equation to provide an aggregate UF applied to a vehicle's charge-depleting mode results. The UF is an estimation of the fraction (percentage) of driving in the initial mode (charge-depleting), at the beginning of each day for a given data set.
Society of Automotive Engineers [sae]