sooner than you would see with a DC truck,” says
Spaar of EnerSys. “So if you’re lifting high at the end of
a shift, it could put you over the limit.” Larger-capacity
batteries designed for AC trucks and “lockout” systems that prevent lifting if the state of charge gets too
close to 20 percent will help prevent overdischarging.
Overdischarging can also happen when lift truck
operators in a facility that uses opportunity or fast
charging cut short or skip scheduled breaks. Those
breaks are essential windows for charging batteries;
operators who miss some breaks are likely to run
batteries down below the minimum before their shifts
end, says Aerovironment. Making break schedules
mandatory and using a properly sized charging system
will help to prevent this problem.
x Moisture. Moisture can cause corrosion on the
battery connectors and tray, which allows voltage leak-
age from the battery to the frame of the lift truck—a
situation that can cause the truck’s electrical system
to ground fault, says Sanders. Moisture, by the way, is
not just a problem in hot, humid climates. It can also
become a problem when batteries are overwatered
or when the fans in high-frequency chargers draw in
moist air and blow it over batteries and associated
electrical components.
The best method of preventing humidity-related
corrosion is a simple one: keeping the battery tops as
clean and dry as possible. Rubenzer of Storage Battery
Systems also recommends fully insulated, bolt-on
cables, which are less susceptible to moisture-related
corrosion. Be sure, too, to keep high-frequency char-
gers away from wet or washdown areas, he says.
x “Parasitic” loads. Some integral devices and
optional features, such as heaters, fans, and GPS, get
their power from the same batteries that power the
lift truck. While the energy draw of any one device
may be low, a battery under such constant “parasitic”
loads may require a refresh charge more frequently
to counteract the higher battery self-discharge rate,
says Sanders. This will negatively affect performance
and life. To reduce or eliminate the need for refresh
charges, be sure to use a battery with enough capacity
to handle the total demand for an entire shift.
x Outdated chargers. Technological advances mean
that today’s lift trucks—and the demands they place
on batteries—are different from those of a decade ago.
Yet many people who regularly update their forklifts
have 10- or 15-year-old chargers, notes Amato. “Some
of the outputs of those chargers have not kept up with
the requirements of today’s battery,” he says. He rec-
ommends verifying that existing chargers are adequate
for your current battery applications.
x Pushing loads, driving uphill, and heavy lifting.
Regularly driving up inclines, pushing loads (long
frowned upon by lift truck manufacturers), and high
lifting of heavy loads can quickly drain batteries while
placing physical strain on trucks. There is no adverse
effect on battery service life, but the kilowatt-hour
consumption is higher and the battery should be sized
accordingly, Rubenzer says. If those activities occur
daily, consider using the highest ampere-hour-capaci-ty battery available, he adds.
THE POWER OF PREVENTION
Lift truck batteries are designed to work for five
years, or 1,500 to 1,800 cycles, assuming they are
used and maintained correctly, says Vanasse. “If a
battery doesn’t last that long, then it’s probably your
own fault,” he observes. That’s why the experts we
consulted for this article agree that regular preventive
maintenance (PM) is a must for maximizing battery
life and performance.
Even fleet managers who scrupulously follow a PM
schedule for their lift trucks may not do the same for
batteries. But batteries are costly and they’re critical to
an operation’s productivity, so there should be a regular PM schedule in place to make sure they’re getting
cleaned, equalized, and watered appropriately, says
PowerDesigners.
For many fleets, the most effective way to do that is
to use a battery monitoring system that collects data,
issues alerts, and creates reports on such things as
cycles, equalization, watering, temperature, and state
of charge. “In the past, you wouldn’t recognize a prob-
lem with a battery until it was too late,” says Spaar.
“You could go a year or more before seeing a fall-off in
performance. With the information systems available
now, you can know the same day when somebody
didn’t water properly or overdischarged.”
In Vanasse’s view, monitoring systems are invalu-
able tools for both battery and fleet management. “If
you don’t measure and make use of that data, you
can’t improve anything,” he says. Put that information
together with a preventive maintenance program, and
fleet managers can take a much more active role in
extending the life of their batteries. c
TOBY GOOLEY IS A SENIOR EDITOR AT DC VELOCITY.
