Automotive Engineering - April 2021 - 30

Pumping
EV heat

The heat-pump-equipped
Niro EV with the author.

Heat-pump technology is a game-changer for the widespread adoption of
electric vehicles, says a service-tech training expert and EV owner.

by Craig Van Batenburg

30 April 2021

to heat antifreeze for the heater core - an " old-school "
solution! Volt uses its ICE for heat in certain conditions,
but not always.
In 2020 when the Bolt's lease was up, it was time to
look for a new EV for our training work as well as for longer-distance driving. The Hyundai Kona EV was on my
list but its cousin, the Kia Niro EV, won out. Why? The
Niro features a heat pump, rather than hot glycol, to heat
the cabin. Heat pumps are not new in EVs: Nissan offered
one in 2013 on upper-trim models of the Leaf, and Kia's
Soul EV brought a slightly improved heat pump. The Niro
EV takes the technology one step further.

Coolant vs. heat pump
When affordable modern electric cars began entering
the global market in 2010, their ability to keep driver
and passengers comfortable in cold weather - without
compromising driving range - became a concern for
customers and EV development engineers. To provide
their cabin heat, approximately one gallon (3.78 liters)
of coolant was heated using the high-voltage battery
for power. The hot coolant was then pumped into the
heater core. This approach has been around since
1893, when the pioneering mechanical engineer
Margaret Wilcox patented a method for warming the
AUTOMOTIVE ENGINEERING

BOTH IMAGES: ACDC

T

he Automotive Career Development Center (ACDC) that I
founded over 20 years ago provides training and tech support to the world's independent electric-vehicle (EV and hybrid) technicians, who will be asked to fix and maintain the
systems as they age. Our facility in central Massachusetts includes a
variety of hybrid, plug-in hybrid and battery-electric vehicles (BEV)
that we use for both teaching and research. It has also supported my
own investigations into cabin-heater technology and its annoying
" your range may vary " impact on BEV use in northern climates.
This curiosity began when I bought a new 2011 Chevrolet Volt to
add to the ACDC fleet. The Volt, a series-type hybrid, has an electriconly range of about 35 miles (56 km) in ideal thermal conditions. If I
drive back roads at 35 mph (56 km/h), the Volt may deliver 40 miles
(64 km) of pure-electric use before the combustion engine kicks in.
During winter, however, that EV range plummets to less than 20
miles (32 km).
A couple of years after buying the Volt, a used 2011 Nissan Leaf
came our way. This early EV, with its 24-kWh air-cooled battery,
could go about 80 miles (129 km) per charge in the summer, but only
make 50 miles (80 km) in winter. Then in 2017, ACDC leased a
Chevrolet Bolt EV. It offered a big jump in summertime range - 230
miles (370 km). But when the mercury dropped so did the Bolt's
driving range, to 160 miles (257 km).
Life with an electrified vehicle in New England was shaping up to
be problematic. What did they all have in common? The Leaf and
Bolt all generate cabin heat by using their high-voltage battery pack



Automotive Engineering - April 2021

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