Ground Vehicle Standards Newsletter - June 2014 - 3

The value ProPoSiTioN of a baTTery PaCk
By bob galyen, Sae international battery Steering Committee Chairman
Adapted from an article in Automotive Engineering Online
Sometimes we techies need to step out of our labs and offices
and take our ideas to the average consumer. I want to tackle
something the public knows little about: the value proposition
of a battery pack.
I am not trying to achieve a technical description, but a
layman's understanding. Many people are skeptical of
electrified vehicles (EVs), and specifically the battery pack,
because it is the most expensive part of the auto. If we can help
the industry build an explanation that is more accessible to
society, the industry (and the world) will benefit.
The primary component of a battery pack system is an
electrochemical cell-it's all about the chemistry. The cell is a
combination of chemicals that permit the storage of energy
in the form of chemical compounds. These cells require
mechanical support via packaging in the form of frames and
fasteners. They also need electrical circuits for proper charging
and discharging that require control software. This includes
both low-voltage communications and charge control, along
with the high voltage and discharge control.
Transportation application manufacturers are very respectful
of the SAE International Standards Steering Committee priority
list: 1) Safety, 2) Performance, 3) Life, and 4) Cost. There is a
clear focus on the ultimate safety of battery systems for EVs.
After safety, the most important factors are energy and power
dependent on application requirements. Clearly, an EV is
sensitive to volume and mass considerations, as vehicle design
is limited by physical space and weight. Life and cost play key
roles in the calculation of the value proposition.
Automotive manufacturers work very hard to design vehicles
to match a particular demographic group that will buy EVs.
These consumers have various driving behaviors, from mild
(the grandma that drives like a turtle to the grocery store twice
a week) to severe (the daily long-haul commuter who speeds
through traffic). The combination of Father Time (calendar life)
along with the behavior of the driver (which the industry calls
duty cycle/usage life) determines the rate at which the battery
pack system deteriorates in energy-storage capacity.
In the auto industry, we typically express this "life expectancy"
in mileage (usage life) or months of service (calendar life).
These criteria are typically the matrix we use in warranty policy
and enforcement. These factors hold true in all forms of EVs,
which we call xEV and include plug-in hybrids, regular hybrids,
and pure electrics.
At this point in time, the requirements for repurposing are not
well defined (in most cases). There are so many applications
being considered for repurposed batteries that there is a
plethora of requirements to be documented. Many of these
are electrical requirements similar to those from the National
Electric Code from the U.S. government. Although the SAE
International battery standards committees do not write for

Robert "Bob" Galyen is President of Business Development of NA/EU,
Amperex Technology Ltd., and Chief Technical Officer, Contemporary
Amperex Technology Co., Ltd., and Chairman of the SAE International
Battery Standards Steering Committee.

governmental rulemaking, the standards they create are largely
adopted and enforced as guidelines for good practice.
Most of these applications have a more narrow range
of performance than an automotive application, as the
requirements for power and energy for repurposed products
are defined within a fairly narrow band. Consequently, the
repurposed product design is typically not as stringent as an
automotive application. Safety is still the No. 1 consideration,
but power and energy are achieved by proper series/parallel
cell configurations, as volume and process are significantly less
important in most repurposed products.
For example, a power application may have more cells in series
to achieve higher voltages and an energy application may have
more cells in parallel to provide additional capacity. Since the
repurposed application is probably stationary, the need for
energy/power density is less severe than in automotive usage.
Most secondary applications for repurposed EV batteries
are for energy-storage systems, including renewable energy

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