july2023 - 25

condenser coils will prevent rust and
early component failure.
" Just hit it with a garden hose to
clean those fins out to ensure adequate
airflow through the condenser coil, "
suggested Westermann.
The TriPac product manager also
said to ensure the evaporator area has
adequate airflow during inspections
and is not blocked by tools, duffle
bags, chains, or whatever else a driver
may have packed near the APU.
What's new with
diesel APUs?
One thing truckers hate is to pull
over and wait for a forced regeneration
cycle of the engine's aftertreatment
system. A diesel APU's DPF also
needs to burn off soot, which, for the
TriPac Evolution, requires a driver to
maintain highway speeds for 60 to
80 minutes, Westermann explained.
If they can't, the driver would have
to manually initiate a forced regen
of the APU's system. If they don't do
that within 10 to 15 hours, the APU
would shut down.
With the new 3rd Generation
TriPac-which goes into production
this month-iterated to meet EPA
Tier 4 compliance, Thermo King
took the opportunity to completely
redesign the aftertreatment system.
(This is only available on the 50-state
compliant model, not the 49-state
compliant version.)
" The advantage of our new system
is it requires no driver interaction-
it's completely passive, " Westermann
said. " And the time of that regeneration
is reduced, on average, down to
eight minutes. "
The 3rd-gen TriPac also uses 25%
of the fuel per hour that idling would,
which Thermo King said saves an
average of 2,500 gallons of fuel per
year. If diesel costs $3.50 a gallon,
an APU-equipped truck would save
$8,750 per year.
Both 3rd-gen models have the
option to utilize TracKing telematics,
which provides fleets with run
hours, cabin temperatures, and fuel
tax reporting, as well as maintenance
alerts and software updates
in real time.
Rubly said that if an APU has a
fuel-fired heater, it should run for 30
minutes each month. Carrier's just-released
Aspen APU improves upon
this by " provid[ing] electric heating
via its powerful generator, which
eliminates the need for the monthly
operational tests required of a fuelfired
heater, as well as the related fuel
consumption, " Rubly said.
The Aspen also runs self-diagnostic
tests, which take a few minutes and
report any problems via fault codes.
The control interface also provides
fault codes, operating temperature,
and voltage data.
" Additionally, the unit keeps tabs
on system run-hours, enabling automatic
alerts as to when service is
due, " Rubly said.
To support the Aspen, Carrier developed
CabinTech software, " which
provides technicians with comprehensive
system insights, including the
ability to review diagnostic information,
graph real-time run parameters,
and configure APU system operating
parameters and preferences via
connection to a laptop, " Rubly said.
Electric APU
maintenance and
innovations
Rubly noted that upfitting an electric
APU with lithium-ion batteries reduces
maintenance needs and improves
driver satisfaction. They cost more
upfront " but offer significantly longer
battery operational time and lifespan, "
he added.
AGM batteries, on the other hand,
cost less though they " require replacement
after three to four years due to
degradation of battery performance, "
Rubly noted. " If a driver is complaining
of short run times with a batterybased
APU, the battery is typically
the culprit. "
Carrier Transicold's ComfortPro
electric APU also uses an isolator to
ensure the truck start batteries don't
degrade due to APU usage, which
helps to extend battery life and mitigates
potential dead battery callouts
on the tractor itself.
According to Go Power, putting
solar panels on the cab roof can triple
the life of APU batteries.
" Because the solar power is keeping
the batteries within the healthy
range, they are not sulfating, which
means they degrade at a much slower
rate than usual, " O'Connor said. " So,
the benefits here would be less battery
replacement and fewer service calls
for jumping dead batteries. "
He added that for diesel APUs, the
solar system keeps the main battery
at a higher state of charge, which
allows the APU motor to run less.
The next question is what kind of
maintenance the panels need.
" The panels can be walked on and
are tested to withstand 2-inch hailstones
fired at 51mph. These kits are
rugged and can be expected to last
a long time, " O'Connor concluded.
July 2023 | FleetMaintenance.com
25
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