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because they maintain their capacity in cold temperatures
better than conventional lead-acid batteries do, says Purdy.
The Raymond Corp. currently is partnering with the New
York State Energy Research and Development Authority
(NYSERDA) to test lithium-ion batteries in a cold storage
environment. They have performed well so far, but more
research is required, he says.
… AND CONCERNS
All this may sound too good to be true. There must be a
catch, right? Indeed there is—there are several, in fact.
One concern is that as demand for mobile devices and
electric and hybrid vehicles increases, there could be more
competition for the batteries’ raw material. Lithium is
recovered from brine in saline lakes and flats or extracted
from hard rock using open-pit or underground mining
methods. The main producing areas are Chile, Argentina,
Australia, China, and Zimbabwe, and to a lesser extent,
Nevada. There’s no immediate danger
of a shortage, but any time a market becomes dependent on a material
that originates in a limited number of
remote areas, there’s reason for caution.
Once extracted, the lithium is combined with various minerals and chemicals to create the material used in batteries. Which “recipe” is used depends
on the battery application. That has an
impact on safety, a major consideration
for battery users.
Everyone’s heard about overheated or
damaged laptop and cell phone batteries bursting into flames or exploding, a
phenomenon known as “thermal runaway.” But lift truck
batteries are different from the ones used in consumer electronics, and reputable battery manufacturers and
assemblers are diligent about the safety of their products.
For example, Flux Power, a Vista, Calif.-based provider of
li-ion battery packs, has said that the lithium iron phosphate it uses is not prone to thermal runaway, and that
its battery management system will shut down the battery
pack if the sensors in any individual cell detect temperatures outside a prescribed range. Similarly, Chicago-based
AllCell Technologies incorporates a proprietary passive
thermal management system into its battery packs. That
system uses a graphite composite material to surround
individual lithium-ion cells, physically isolating them and
absorbing and conducting heat away from them to prevent
fire or damage.
In fact, an appropriately designed battery management
system is a necessity when lithium-ion is involved. In a
discussion about safety on its website, Denmark’s Lithium
Balance says that li-ion batteries do not tolerate overcharg-
ing and that safe operation requires constant monitoring to
protect the battery pack from excessive current flow, as well
as a switching circuit to connect and disconnect the battery
from the electrical load. A battery management system
should provide these controls, it says.
Because lithium-ion batteries have a sharp “shut-off,”
operators won’t see the performance decline they experience with lead-acid batteries, says Raymond’s Purdy.
They’ll need the kind of alerts that control systems on
lithium-ion batteries in consumer applications provide,
but lift trucks designed for traditional batteries “are not set
up to listen to that kind of communication,” he observes.
Raymond is devoting considerable resources to developing
and testing the communication interface between the truck
and li-ion batteries, with the hope that it will become a
public standard, he says.
Another potential drawback of li-ion batteries when used
in industrial lift trucks is the significant difference in weight
between lithium-ion units and their lead-acid counterparts. While lightness can be an advantage at times—such
as in the automotive industry—many
lift trucks depend on heavy lead-acid
batteries to counterbalance load and
operator weights, says Tomaszewski of
EnerSys. If the manufacturer has to add
a heavy weight to the truck in addition
to the li-ion battery and its compartment, it “could potentially compromise
the economics of truck design and manufacturing,” he says. For that reason,
lithium-ion batteries have largely been
relegated to pallet trucks and AGVs.
Lithium-ion batteries also come with
a hefty price tag, the single biggest factor holding back the adoption of lithium-ion in material handling applications. An often-quoted
2013 report by Navigant Research estimated that li-ion
batteries cost around $400 to $700 per kilowatt-hour, compared with $150 to $400/kwh for lead-acid batteries. Prices
fluctuate, but currently, price differentials are “in the range
of four to five times the cost of lead-acid when calculated
on a watt-per-hour basis,” estimates Steve Dues of Crown.
Proponents, however, counter that li-ion actually compares
quite favorably on total lifetime cost, owing to its energy
density, maintenance-free characteristics, low electricity
requirements, high productivity, and a lifespan that’s three
to five times that of comparable lead-acid batteries.
Regardless of the potential benefits, lithium-ion will
go nowhere unless the lift truck and AGV manufacturers
approve their use in individual vehicle models sold in
specific markets. That’s a process that is necessarily rigorous and time-consuming because both customer safety
and product integrity are at stake. Toyota, for instance,
offers several lithium-ion battery products in Europe but
has approved just one in North America. Scott Carlin,
electric product planning and product support manager for Toyota Material Handling, U.S.A. Inc., says his
