Power platform: Lithium-ion battery chemistry offers a range of advantages for cordless power tools
Stephani L. Miller
Not surprisingly, most contractors are more concerned about a tool’s productivity than knowing about the battery chemistry that drives it. But a few power tool manufacturers have recently brought to market a new battery platform that might actually make your customers consider their battery options more closely.
Lithium-ion (Li-ion) batteries are widely used in consumer electronics like cell phones and laptop computers, and for years cordless tool manufacturers have been interested in leveraging the technology for their products, as well. But battery manufacturers have only recently achieved Li-ion formulations that will support high amp-drawing power tools.
In cordless power tool applications, Li-ion batteries offer several advantages. More-compact battery cells yield lighter-weight battery packs, and Li-ion batteries allow for more charging cycles than NiMH or nicad batteries for longer battery life. Manufacturers say that Li-ion batteries also have no memory effect, so they can be charged at any point in their cycle. They require less time to fully charge, they store a charge longer than nicad or NiMH batteries when not in use, and there is no power drop-off as the battery discharges.
Manufacturers warn, however, that the lack of power drop-off may make it difficult for users to know when the battery needs to be recharged. This may lead to over-discharging the battery, which can damage cells and significantly reduce or eliminate their charging capacity, 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 [present in early] nicads” To help contractors keep track of their battery’s charge, most manufacturers have incorporated a power-level gauge on their Li-ion battery packs that show how much charge is left, though it is up to the tool user to take advantage of this feature.
The key benefit to Li-ion batteries is the ability to provide more power in a fighter-weight package, a feature that has given manufacturers multiple choices for how to develop their Li-ion lines. “I think it’s a way for everyone to expand the cordless market,” says Christine Potter, group product manager for DeWalt.
Milwaukee Electric Tool (circle 102), the first to market last year, and DeWalt (circle 103) have taken advantage of Li-ion’s power-to-weight ratio by developing cordless tool families in higher voltages–28 volts and 36 volts, respectively–that they say provide the power and performance of corded tools with weights comparable to lower-voltage products. Makita (circle 104) and Metabo (circle 105) have focused their energies on improving ergonomics by offering lighter-weight tools in popular voltages: 18 volts for Makita; 14.4 and 18 volts for Metabo. Bosch Power Tools has taken a divided approach with initial introductions of two 10.8-volt tools that deliver more battery power in a smaller package and a 36-volt 1-inch rotary hammer the company says provides corded power in a compact, lightweight design (circle 106).
Although Li-ion batteries show substantial promise, manufacturers are confident that nicad batteries will continue to remain the standard for several years yet. “For the next three to five years, we still expect nicad to be the largest majority of sales, but if Li-ion continues to develop the way it has with [these] capacities it should become the dominant platform in the marketplace,” predicts Bosch’s product manager for cordless tools, Edwin Bender.
Contractors are heavily invested in existing battery platforms, Bender notes, which creates a hurdle for Li-ion tools. Most users will most likely not want to make the investment to replace all their current tools, batteries, and chargers just to get models that are lighter weight and more comfortable to work with unless they see value in other features offered by a particular Li-ion tool line. DeWalt says one way it’s addressing this issue initially is by offering 36-volt tools that provide the power-to-weight ratio appealing to users who traditionally must rely on corded models.
Li-ion tools also have premium price tags–about 30 to 50 percent higher than other battery platforms–that are not likely to decrease until more manufacturers introduce products.
Though it will take some work to help customers justify the cost, Makita product manager Rod Dick notes that “The true cost of batteries extends beyond the cash register. Extending battery life improves investment value and increasing runtimes similarly increases jobsite productivity. These factors make the true cost of ownership very attractive.”
Manufacturers advise retailers to focus on the features of each tool and the value and benefits that Li-ion platforms offer.
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