may2021 - 39

who are subject to the 34-hour restart rule that
may result in an extended break 'at home' in the
truck cab while on the road. In contrast, electric
APUs tend to be chosen by regional carriers where
the driver may need air conditioning for a single
overnight trip. "
Specific to the use of lithium batteries, Wilson
advised of system-specification challenges.
" The only drawback when we're dealing with lithium
batteries [is that] lithium batteries can't be left
out in the cold; they can't be left out in the heat, "
Wilson said. " They have to be in the cab, which
means you have to add a battery in the sleeper. "
He added that while lithium batteries must avoid
extreme temperatures, the size of the battery pack
is about half that of the traditional lead battery
setup. Wilson explained that compared to a system
utilizing Group 27 batteries - typically a set of
four - to get the electrical equivalent in a lithium
battery powered system requires the space of less
than two Group 27 batteries, in terms of volume.
Maintenance, charging, and
battery management
Aside from fuel, noise, and emission reductions,
arguably the greatest benefit offered by
electric APUs is the reduction in maintenance
requirements.
" Electric APUs are also selected for their
low-maintenance aspects, " Rubly stated. " With
a simpler design than [diesel] APU systems
and only a few moving parts, there is far less
to service with an electric APU, and there is no
engine-related maintenance such as oil changes
and various filter replacements. "
The closed-system nature of electric APUs
creates an environment to be seemingly simple
in terms of maintaining its operation and performance
capabilities.
" That's the beauty of it - because everything is
electronic other than the compressor itself and the
Freon lines, there are no different maintenance
[requirements] than you would have on the truck
anyway, " Wilson advised. " The compressor itself
is fully enclosed; you never really need to touch it.
" If you ended up with a Freon leak, you would
handle that the same way you would handle it if
it was just in the truck, " he added.
From a maintenance perspective, electric APUs
inherently require proper battery management.
" Electric APUs are generally charged via the
truck engine alternator, " Rubly explained. " Carrier
Transicold's ComfortPro electric and diesel APUs
offer optional shore power kits that allow the driver
to power the APU from any 115V outlet, providing
climate control and battery charging while utilizing
zero fuel. " He added that the ComfortPro electric
APU can provide 7,500 Btu/h of air conditioning for
up to 11 hours under normal operating conditions.
Along with understanding the charging needs
of the battery, a fleet should remain cognizant
of battery lifecycle expectations and when to
perform appropriate replacements.
" Battery changeouts are the main maintenance
requirement of electric APUs, " Rubly said. " With
AGM batteries used in most systems, battery
changes may be necessary in a 24- to 36-month
May 2021 | FleetMaintenance.com
39
timeframe, depending on use and number of
charge cycles. "
However, fleets need be aware of the type of
battery utilized in an electric APU system, as
maintenance and replacement intervals can
vary drastically.
" The lithium battery should have, in normal
usage, at least a 10-year life span before it even
needs to be touched, " Wilson stated.
Battery technology and the
future of electric APUs
Electric APUs are available on the market today.
Though, as the horizon nears with impending regulations
for emissions, idle hours, noise pollution,
and the industry's goal of electrification, an understanding
of the future of battery technology, and its
applications to the electric APU space, is important.
" The emerging technology is going to be
[focused on] how to store energy, " Wilson said.
" Before, it was lead batteries. Big, heavy, and they
go bad after a couple of years because we really
work them to death in this market. " Wilson
confirmed the industry more readily continues
to adopt lithium battery technology as a replacement
for AGM batteries.
" Lead [batteries] will always have their place
in starting the engine; lithium batteries, they just
can't do that kind of load in starting an engine. But
for lightweight, long-term storage, lithium - right
now - is a way to go. "
Lithium-ion batteries may receive negative
attention today as potentially dangerous, though
Wilson heeded a generalization of the lithium
category is inappropriate.
" Lithium scares a lot of people, " he said. " It
doesn't need to scare you as long as you understand
it, but everybody just throws out lithium
like it is all the same. There are six different chemistries
of mainstream lithium batteries; some are
safer than others, and some are more volatile. "
For instance, there is a distinct difference in
chemistry and application for lithium cobalt
» Xantrex utilizes lithium iron phosphate
chemistry in their lithium-ion batteries.
" The lithium battery should have, in normal
usage, at least a 10-year life span before
it even needs to be touched, " said Don
Wilson, applications engineer at Xantrex,
a Mission Critical Electronics brand.
Image courtesy of Xantrex
batteries compared to lithium iron phosphate
batteries. Wilson explained that while the lithium
cobalt battery is used for lightweight, small-energy
storage, for applications in the cellphone, airline,
and car industries, it can be more volatile.
" When we are talking about energy storage in
a vehicle - not to drive the vehicle like a Tesla
- but storage in a vehicle for electrical loads,
lithium iron phosphate batteries are way less
volatile, " Wilson advised. " You don't have the
burning problems with lithium iron phosphate
that you do with lithium cobalt. And so, when
you look at safe energy storage, lithium can be
scary, but if you are looking at the right chemistry,
it is really not. "
Xantrex utilizes lithium iron phosphate chemistry
in their lithium-ion batteries. In creating such
a battery composition, Wilson stated that to utilize
such a chemistry, about a 10 percent addition in
weight and about a 10 percent addition in size
was necessary, which was a decisively acceptable
trade-off for the safety offerings.
" They are UL Listed, " Wilson said of Xantrex
lithium iron phosphate batteries. Underwriter
Laboratories (UL)
is an independent safety
science company that provides third-party certification
and can approve UL Listing. UL Listing
means that the company has tested representative
samples of a product and determined that
the product meets specific, defined requirements.
These requirements are often based on UL's
published and nationally recognized Standards
for Safety. " I like the UL Listing because it means
somebody else, who doesn't care how many
batteries we sell, looked at it and made sure it
was safe, " he added.
Integration of such battery technologies into a
fleet's operations today can help with plans for
the future when regulations may move the industry
toward expanded electrification adoption.
Exploring electric APU specification today, even
in limited capacity, can help a fleet understand
which vehicles, applications, routes, etc. may be
most positively impacted with such technology.
Beyond that, testing electric APUs in a fleet today
provides valuable feedback should extensive fleetwide
specification become necessary down the
road with federal regulations requiring reduced
greenhouse gas emissions and more efficient
technologies. But aside from just planning for the
future, electric APUs can be implemented today -
and they offer benefits across multiple channels
for a fleet's organization.
http://www.FleetMaintenance.com
may2021

Table of Contents for the Digital Edition of may2021
