Truck & Off-Highway Engineering - June 2021 - 11

EXECUTIVE VIEWPOINTS
Batteries not the only route
to EV efficiency
Allison CTO stresses efficiency and safety of propulsion units also are critical
to reducing cost, improving performance and ultimately winning over customers.
by Michael Foster
Allison Transmission's eGen Flex
electric hybrid propulsion system can
provide up to 10 miles of full electric drive capability,
which can be set automatically through geofencing
technology for zero-emission zones and passenger depots.
M
uch of the talk around the switchover to
electric power in commercial electric vehicles
(EV) focuses on batteries, whether
it be their range, weight,
energy and power density, or expected
life. Allison Transmission supplies
hybrid propulsion products for
transit buses and is bringing to market
e-axles for battery-electric vehicles
(BEV). For each of those applications,
a different battery chemistry
will win out as OEMs and operators
factor the cost, performance,
duty cycle and lifespan of the batteries
into the vehicle's total cost of
ownership (TCO).
Battery cost is falling but remains
a high-value proportion of the TCO.
For BEV applications, which might
only require one daily discharge cycle
and an overnight charge, nickelmanganese-cobalt
(NMC) batteries
seem to offer the best balance today.
TRUCK & OFF-HIGHWAY ENGINEERING
Other chemistries have a higher cycle life and power capability, but
also come at a significantly higher cost. For hybrids, lithium-titanate-oxide
(LTO) and other chemistries have much higher specific
power and lifespan. With the constant movement of energy level in
a hybrid battery, a higher cycle capability is required.
While batteries are essential, they are not the only
key component in spurring the rollout of commercial
EVs. The propulsion unit - which could be either a
direct or central drive, or an e-axle - converts the
electrical energy from the batteries into kinetic energy
at the wheels. With all the traction power passing
through this unit, the efficiency and safety of the
propulsion unit is also critical to reducing cost, improving
performance and ultimately winning over
customers going forward.
The route Allison is taking for its propulsion sysMichael
Foster,
Allison Transmission CTO.
" We shouldn't
ignore the role that
hybridized ICEs
could play. "
tems, whether e-axle or central drive, is agnostic to
the energy source, which could be a battery pack of
a certain cell chemistry, or a hydrogen fuel cell as a
range extender for the battery pack. Allison is
aware that particular chemistries have the right
amount of power and specific energy available for
different lifecycles but, in supporting OEMs, try to
remain agnostic to competing battery chemistries
and suppliers.
June 2021 11
BOTH IMAGES: ALLISON TRANSMISSION

Truck & Off-Highway Engineering - June 2021

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - June 2021

Truck & Off-Highway Engineering - June 2021 - CVR4
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Truck & Off-Highway Engineering - June 2021 - CVR1
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