The allure of lithium-ion

The first lithium-ion battery-powered lift truck made its debut in Japan in 2008. Pallet jacks and automated guided vehicles (AGVs) powered by lithium-ion batteries have been scooting around European DCs for a few years now. But here in North America, we're a little late to the party. Interest in lithium-ion batteries and battery management systems may be high, but sales remain slow.

Proponents of this energy-dense, highly efficient power source say that's about to change. For the past couple of years, manufacturers and designers of batteries, chargers, and lift trucks have been testing lithium-ion (li-ion, for short) batteries, and some are now commercially available here. While it's generally agreed that li-ion batteries are very promising for material handling applications, how much of the market they'll eventually capture is far from certain.

KUDOS ...

One reason for the growing interest in li-ion batteries is that they have a very high energy density—about triple the capacity of a similar lead-acid battery, says Arlan Purdy, product manager of energy storage systems for lift truck manufacturer The Raymond Corp. They're also attractive because they do not require any watering and give off no gases, he says. And, unlike some other alternative power sources, he adds, lithium-ion batteries "have a little bit of a convenience factor because they use the same electric grid that people are used to"; in other words, the charging process will already be familiar to operators. Lithium-ion batteries are much smaller and lighter than their lead-acid counterparts—perhaps lithium-ion's greatest appeal, notes Mark Tomaszewski, manager, emerging technologies, for the battery maker EnerSys.

In addition, li-ion batteries can be opportunity-charged during operator breaks without adversely affecting battery life, have much longer run times than their lead-acid counterparts, and can be charged quickly, says Steve Dues, vice president at lift truck maker Crown Equipment Corp. That means there is no need to swap out batteries during a shift—or to remove a battery at all, even in a 24/7 operation.

How fast can li-ion batteries be charged? Much depends on the particular cHemiätry of the material inside, but Trineuron, a Belgian supplier of batteries for AGVs, among other applications, claims that the nano lithium-titanate-oxide technology it has adapted from the energy-storage and automotive markets allows for a full recharge in less than nine minutes, and that total time on charge for AGVs with any type of li-ion battery typically is less than one hour a day. On its website, the company cites the example of a Belgian food distributor that put 30 Jungheinrich AGVs with li-ion batteries to work in a new warehouse and projects savings of 1 million euros (approximately US$1.1 million) due to shorter charging times and lower electricity costs.

Food and beverage distributors as well as grocery industry players are particularly interested in li-ion batteries 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 overcharging 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 company is "working to verify that the suppliers and their products meet safety standards and testing protocols" for equipment sold here.

GAINING CONVERTS

Navigant Research's 2013 report forecasts that revenues from the sale of new electric-power technologies for forklifts in North America, including certain types of fuel cells, fast chargers, and li-ion batteries, will grow to $556 million in 2020 from $121 million in 2013. Lithium-ion is expected to make up just a sliver of that total market, perhaps 4 percent. Still, evidence abounds that equipment makers and their customers see a future in this technology. Here are a few examples:

• Yale Materials Handling Corp. now offers a walkie pallet truck with the first commercially available li-ion battery pack recognized by Underwriters Laboratory (UL) in the forklift industry. The lighter, smaller battery allows for a shorter, more maneuverable truck and is backed by a five-year warranty.
• Flux Power introduced a beta version of its 500Ahe LiFT Pack battery for end-rider pallet jacks at the 2015 ProMat show. The company says Toyota and Crown Equipment have approved its battery packs for use in certain pallet jack models and that it has lined up battery distributors and forklift dealers to sell its products. The publicly traded company reports growing quarterly sales but is still in the red.
• Earlier this year, the snack maker Mondelez bought li-ion batteries and battery management systems from Electrovaya for its Toronto DC, and the Norwegian wholesaler Europris reported that in a six-month trial, batteries from GNB Industrial Power "significantly" lowered its forklift fleet operating costs.
• A growing number of vendors, including Storage Battery Systems (SBS) and GS Yuasa, have added li-ion batteries for AGVs to their product lineups.
• Applied Energy Solutions reports that several major retailers are testing its Superion lithium-ion battery and charger pack, which has won two MHI innovation awards.

When asked where the market for lithium-ion batteries will be five years from now, the experts we consulted for this article were cautious in their assessments.

Purdy believes considerably more research and testing will be required to ensure that the batteries—both current and future designs—are properly matched to specific lift truck applications. But if prices come down, he expects that within five years, sales will be "at least equal to fuel cells."

Tomaszewski, meanwhile, says EnerSys sees possibilities in lithium-ion, but right now the company is using it in nonmotive applications only. "Until the cost comes down, we will consider it to be an emerging technology," he says.

In Carlin's opinion, the fact that forklift manufacturers are hiring employees specifically to support lithium-ion and other new technologies suggests that they believe acceptance will grow. "I would expect that over the next five years, testing will continue, and as people become more confident in the overall benefits of the newer technologies, lithium-ion will be embraced as a major alternative to lead-acid," he says.

Steve Dues of Crown agrees that alternative power sources will gain market share as they prove they can solve customers' problems at a competitive cost. But don't count lead-acid batteries out just yet, he says. The hybridization of lead-acid with other technologies like super capacitors, together with improved battery management solutions, could deliver meaningful power and efficiency gains. Lithium-ion may be getting some well-deserved attention, but solutions involving traditional lead-acid batteries, he predicts, "are what will be applicable to the significant majority of the forklift market."