IEEE Electrification Magazine - December 2013 - 10

the energy consumption, battery size or range, cost of the
vehicle, and acceleration performance. With so many
dimensions of improvement, it is difficult to argue against
making vehicles lighter, but perceptions can be obstacles.
at the time of this writing, reports of the volkswagen Xl1
research vehicle point to the possibilities for efficient vehicles. the Xl1 has reported 261 mi/gal (0.8 l/100 km) from a
lightweight vehicle made largely of carbon fibers. it uses a
diesel-electric plug-in hybrid powertrain and demonstrates
efficiencies thought to be impossible only a decade or so ago.

consuming 100 Wh/mi will have roughly a 10-mi range
with a 1-kWh battery pack (1,000 Wh/100 Wh/mi = 10 mi),
whereas a 3,000-lb vehicle will consume roughly three
times the energy and, thus, require three times the battery capacity to provide the same range. to achieve a
60-mi all-electric range, our 1,000-lb vehicle would
require a 6-kWh battery pack. to achieve the same 60-mi
range, a 3,000-lb vehicle would require an 18-kWh
battery pack.

charging Strategies
Perception and buyer behavior
consumers purchase cars based primarily on emotional attachments
and perception. choices are often
made based on the image the purchaser desires to project or an image
that appeals to him/her. the math in
the above examples clearly indicates
that lighter vehicles are better in
many ways, for both the driver and
others. however, consumers often
associate the social status conferred
by a car with its size, plush interior,
or styling, for instance, just as a vehicle's performance has often been
judged by the roaring sound of its
engine. to the extent that our 1,000lb vehicle is large, with a plush interior and great styling, the customer
might become emotionally attached,
but if the same vehicle is small, lacks
a luxury interior, has less than stellar
styling, and makes no roaring
sounds, then the lack of traditional status symbolism
may not engage the customer's emotions. thus, engineering a very efficient vehicle may be much easier than
marketing one.
to be successful with light vehicles, consumers must
make emotional connections with the vehicles. traditional dimensions such as performance and luxury have
already been marketed heavily, but more subtle vectors
such as energy consumption, informational displays,
connectivity, safety, or other attributes specific to electrified vehicles or high technology require significant reeducation and effort. developing the right mix of
elements to appeal to the senses and emotions of customers is as important as engineering the right blend of
power during acceleration.

in the above examples, charging a 6-kWh battery pack for
the light vehicle could be accomplished very quickly with a fast charger or in fewer than 1 h with a
cost-effective 240-v level 2 charger.
alternatively, a standard 120 vac outlet
(current similar to that of a small window air conditioner) could be used for
overnight charging. there are also several options for charging the 18-kWh
pack of the heavier 3,000-lb vehicle. it
could be done in fewer than 30 min
with a dc fast charger or about 3 h
with a 240-v, 30-a charger.
consumers inexperienced with
evs surveyed by auto manufacturers
often say they want their ev to
charge as fast as they can currently
fill their gas tank, with their thought
process being that when they are
traveling and their battery gets low,
they want the convenience of pulling
into a charging station and getting a
quick charge. however, when you ask the same question
of someone who has used an ev for more than a few
months, you get an entirely different answer. experienced
users expect to mostly charge overnight at their home.
they only expect to charge at a public facility when they
plan a trip outside of their normal commute range. in
fact, many experienced ev users are skeptical of fast
charging, concerned that it might reduce their battery life
or battery capacity. one experienced ev user indicated
that it takes about 30 s to charge the battery-15 s to plug
it in before bedtime and 15 s to unplug it in the morning.
as electrified vehicles proliferate, the time and intensity of battery recharging will become an issue for grid operators. While customers without experience believe they
need to charge in very short times, experienced ev drivers
find charging overnight to be quite convenient. however,
battery size is a very important consideration for the cost
of the vehicle, the time required to recharge, and the
amount of peak power consumed to charge the battery.
bigger is not necessarily better.
to understand this issue, let us consider a battery pack
of 1-kWh capacity. charging this battery in 1 h would

Traditional autos
meet the needs of
both short commutes
and longer-distance
travel with one
vehicle and have
thus set that
expectation for
most of the 1 billion
auto owners around
the world.

energy consumption and battery capacity
if you have not previously thought much about energy
consumption in cars, our efficiency scenarios may not
mean much, so let us further explore how energy consumption relates to a car's battery capacity, typically
measured in kilowatt-hours (kWh). a 1,000-lb vehicle

I E E E E l e c t r i f i c ati o n M agaz ine / december 2013

Table of Contents for the Digital Edition of IEEE Electrification Magazine - December 2013