Tools & Equipment Review: Lithium-Ion BatteriesTaking Charge: Lithium-ion batteries may boost the cordless power tool market.

Not surprisingly, most contractors are more concerned with a tool's productivity than the battery that drives it. But an emerging battery technology may cause them to reconsider their battery choices.

Powerful, compact lithium-ion (LI) batteries are widely used in consumer electronics such as cell phones and laptop computers, and cordless power tool manufacturers have been interested in them for years. But only recently LI formulations were achieved to support high-amp-drawing power tools. And pros are taking notice.

"[The technology] gives you the capacity to do everything that you need to do in construction without dragging a cord behind you … or trying to find a space to plug something in," says Steve Whitley of Zum Bauernhof Construction in Forsyth, Mo., who recently tested a Milwaukee lithium-ion tool. "They virtually let you go cordless."

In cordless power tool applications, LI batteries offer several advantages. More-compact battery cells yield lighter-weight battery packs and unlike other types of batteries, LI batteries have no memory effect, so they can be charged at any point in their cycle. They also require less time to fully charge, store a charge longer than nicad or NiMH batteries when not in use, and don't have power drop-off as the battery discharges.

Manufacturers warn, however, that this lack of power drop-off may make it difficult for users to know when the battery needs recharging. "If you over-discharge [an LI battery] it loses the ability to become charged again," notes Terry Tuerk, product manager for Metabo. "Tool manufacturers will have to point out to users the danger of over-discharging, kind of like the memory effect of nicad."

Power Platform

Because LI batteries provide more power in a lighter-weight package, manufacturers have multiple choices in how to develop their LI lines. "I think it's a way for everyone to expand the cordless market," says Christine Potter, group product manager for DeWalt.

Each tool manufacturer with LI products has approached development differently. Milwaukee and DeWalt have taken advantage of LI's power-to-weight ratio with cordless tool families in higher voltages–28 volts and 36 volts, respectively–that aim to provide power and performance comparable to corded tools. Milwaukee also recently introduced an 18-volt LI line. Meanwhile, Makita and Metabo are focusing their energies on improving ergonomics in popular voltages: 18 volts for Makita; 12, 14.4, and 18 volts for Metabo. Furthermore, Bosch has taken a divided approach with two 10.8-volt tools that deliver more battery power in a smaller package and one 36-volt tool.

Dan Brown of DH Brown Construction in Newbury, Mass., recently tested the Bosch 10.8-volt impact driver with an articulated head. "The battery is smaller and has a great amount of power to it," he says. "It lasts long enough. It's not heavy."

The extended run time is a convenience for pros working far from an electrical outlet, says Whitley. When working with other cordless tools, "If you're up on a roof, or down on a crawlspace... you've got to stop what you're doing and get another battery," he says. "And you'd better have one on the charger that's full."

Rob Byer, a journeyman plumber for J.E.M. Plumbing in Fallston, Md., who tested a DeWalt LI combo kit, says that despite working 40-hour weeks, he only needs to charge the tool once every seven days.

Although LI batteries show substantial promise, manufacturers believe nicad batteries will remain the standard for now. "For the next three to five years, we still expect nicad to be the largest majority of sales, but if LI continues to develop the way it has … it should become the dominant platform in the marketplace," says Bosch's product manager for cordless tools, Edwin Bender.

Conversion Issues

The biggest downside to LI tools may be their premium pricetags that are not likely to decrease until more manufacturers introduce them. The cost of LI-powered tools is roughly 30 percent to 50 percent higher than tools sporting other battery platforms.

It will take some work to help customers justify the cost. "The true cost of batteries extends beyond the cash register. Extending battery life improves investment value and increasing run times similarly increases jobsite productivity," reminds Makita's product manager, Rod Dick. "These factors make the true cost of ownership very attractive."

By offering a new cross-compatible charger that works with both LI and nicad batteries, Milwaukee, for instance, is providing a good reason for pros to invest in the new LI tools. In a slightly different twist, some of Metabo's existing 12-volt, 14.4-volt, and 18-volt tools can be purchased with LI batteries. The company also sells an LI battery and charger kit separately for use with these tools.

Most industry experts agree that LI technology will expand beyond traditionally cordless power tools. They predict the superior energy storage characteristics of LI will take air hoses off many pneumatic nailers for good. Also, some corded tools with high power demands, such as routers, miter and table saws, and planers, will likely become cordless as LI batteries become more common. Meanwhile, expect to see LI batteries replace the cords on shop vacs, outdoor power equipment, and other products where portability is a plus.

Those who've used the technology say they're sold on LI. Adds Brown, "I'm seriously thinking of getting rid of my larger 18-volt [tools]."

–BUILDING PRODUCTS

This article first appeared in PROSALES magazine. Monica Soladay and Michael Springer contributed to this article.

Makita

Makita. The LXT LI line offers 18-volt power at 12-volt weight. The company says the batteries and charger produce almost three times the lifetime work and two times more charge cycles than nicad batteries. The line includes a hammerdrill/driver, drill/driver, impact driver, circ saw, and recip saw. 800-462-5482. www.makita.com.

Metabo

Metabo. The company's three LI batteries are available as upgrades with several cordless tools but a battery and charger kit also can be purchased separately for use with existing 12-, 14.4-, and 18-volt BSZ drill/drivers and several other tools. The company says the batteries offer 40 percent less weight, but 40 percent higher performance and 100 percent more life. 800-638-2264. www.metabousa.com.

Milwaukee

Milwaukee. First on the LI scene last year, Milwaukee has expanded its line of V28 28-volt LI tools and has added a V18 18-volt line and the ability to use LI batteries in existing Milwaukee 18-volt nicad tools. The lithium manganese batteris offers higher amp hours for more work over the batteries' life and a stable thermal chemistry, the firm says. A charger compatible with both nicad and LI batteries is also available. 800-729-3878. www.milwaukeetool.com.

Bosch

Bosch. Bosch offers its Litheon LI-powered tools in two voltages: The 10.8-volt I-Driver and Pocket Driver and the 36-volt, 1-inch SDS-plus rotary hammer. The firm says the batteries offer up to five times more cycle life than competitive lithium-ions. A 36-volt drill/driver, recip saw, and 6-1/2-inch circ saw are planned by the end of the year. 877-267-2499. www.boschtools.com.

DeWalt

DeWalt. The company developed a new generation of batteries with nano-phosphate lithium-ion technology it says offers a high level of power, durability, and life compared to conventional lithium technology. The line includes a hammerdrill, recip saw, 7-1/4-inch circ saw, impact wrench, rotary hammer, jigsaw, and flashlight. 800-433-9258. www.dewalt.com.