Page 22 - Issue 3 2023

TECHNICAL

Battery
Irrespective of the type of EV, the battery
is primarily used to store energy to propel
the vehicle, either completely, or in
combination with the ICE. The capacity
of the battery will depend on the type
of EV, and passenger car range generally
depends on the average speed at which
the car is driven. There was a recent
announcement of a vehicle equipped with
a 140 kWh battery giving an 800 km range.
Most of the EPMs on the road today use
400 V batteries. EV buses and trucks are
Figure 3: Plug-in hybrid 600 V vehicles. Traction inverters which
can handle higher voltages make 800 V
systems possible in new passenger cars.
The full EV Since the battery’s capacity affects
The fully electric EPM relies entirely on battery power to drive the vehicle and is the range of the vehicle, increasing its
recharged externally as well as by regenerative braking. The size of the battery capacity would increase the vehicle’s
determines the range of the vehicle, which can vary from <100 km to >600 km. Increasing range between recharges; but it also
the battery size increases the range, but also the mass of the vehicle, and reduces increases the vehicle’s mass and the
available space. space occupied by the battery. Currently,
EV battery research is focused on
increasing the energy density of EV
batteries, which reduces physical size and
mass for the same energy capacity, and
would extend the range of the vehicle.

Battery types
Two battery types are currently in use
in EVs: Lithium-ion ( LiFePO 4) which is
the battery of choice for full EVs, and
nickel metal hydride (Ni-MH) which is
commonly used in hybrids. Numerous
variations of the Li-ion battery have been
developed, including material changes,
Figure 4: Full EV and there are regular announcements of
a new “breakthough” in this field. Most
EV components are still at laboratory stage. A recent
All EPMs have four major electrical components: a battery, a traction inverter, a controller development is the use of a silicon-based
and one or more electric motors. anode by Mercedes Benz, which promises
a 40% improvement in energy density
and extended driving range per charge.
While the Li-ion battery is considered
the best option at the moment, other
technologies are under consideration.
The most promising option appears to be
the solid-state battery.

Solid-state batteries (SSB)
Solid-state batteries are currently one
of the most promising technologies.
Figure 5: Electric people mover (EPM) components The principal difference is the use of an

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