Description / Abstract:
This SAE Recommended Practice defines a standardized test method
to determine the expected service life, in cycles, of electric
vehicle battery modules. It is based on a set of nominal or
baseline operating conditions in order to characterize the expected
degradation in electrical performance as a function of life and to
identify relevant failure mechanisms where possible. Accelerated
aging is not included in the scope of this procedure, although the
time compression resulting from continuous testing may
unintentionally accelerate battery degradation unless test
conditions are carefully controlled. The process used to define a
test matrix of accelerated aging conditions based on failure
mechanisms, and to establish statistical confidence levels for the
results, is considered beyond the scope of this document.
Because the intent is to use standard testing conditions
whenever possible, results from the evaluation of different
technologies should be comparable. End-of-life is determined based
on module capacity and power ratings. This may result in a measured
cycle life different than that which would be determined based on
actual capacity; however, this approach permits a battery
manufacturer to make necessary tradeoffs between power and energy
in establishing ratings for a battery module. This approach is
considered appropriate for a mature design or production battery.
It should be noted that the procedure defined in this document is
functionally identical to the USABC Baseline Life Cycle Test
Procedure.
Field of Application—
Electric Vehicles
Product Classification—
Electrochemical Storage Devices
Form—
An Electric Vehicle propulsion battery will consist of a battery
configuration of several (typically 12 V) modules interconnected in
one or more series strings. This document provides test methods to
determine the life expectancy of such modules, including but not
limited to modules built in accordance with SAE J1797. Use of this
document is intended for single independently packaged modules
operating at ambient conditions (i.e., standard room temperature).
Testing of a fully configured propulsion battery system, especially
when designed to operate at elevated or reduced temperatures,
usually results in reduced expected service life and requires
testing methods beyond the scope of those included in this
document.