The buzz in the cordless power tool industry for the past 18 months has been the introduction of Lithium-ion batteries. This article will bring you up to speed on this new technology.
Nickel based batteries nickel cadmium (NiCd) and nickel metal hydride NiMH) have been in use for cordless tools since Makita first introduced a cordless drill back in 1978. While there have been some problems — such as memory — these batteries have performed well for almost 30 years. One complaint from users was the run time left a lot to be desired — often the battery ran out before the work was finished. In an effort to give users more run time, manufacturers developed larger batteries than the original 9.6v — we have seen the introduction of 12-, 14.4-, 18-, 19.2-, 24-, and 28-volt systems. Of course, larger voltage batteries gave more run time but with a weight gain expense. A 28-volt NiCd battery is much heavier than an 18-volt, but the user got extended run time.
Lithium-ion batteries (commonly referred to as Li-ion) have been in use for years in cell phones and laptop computers because they are lightweight. Battery and cordless tool manufacturers have been working to develop a Li-ion battery because of the attractiveness of light weight. One major concern with Li-ion battery development was heat generation both during use and while charging. This problem has been addressed by all tool manufacturers and has resulted in vented batteries, cooling fans in chargers, and special internal electronics.
The truth is that a NiCd battery cell can produce about 1.2 volts and a Li-ion cell can produce about 3.6 volts for about the same weight. This translates into an 18-volt NiCd battery with 15 cells or a 36-volt Li-ion battery with 10 cells. Simply put, twice the voltage at two-thirds the weight.
In January 2005, at the International Home Builders Show in Orlando, Milwaukee Electric Tool introduced the first redesigned line of Lithium-ion powered cordless tools — the V28 series. Since that time Bosch, DeWalt, Metabo, Makita, and Ridgid have introduced a line of newly designed, Lithium-ion powered cordless tools, with voltages ranging from 10.8 to 36.
In addition to more power with less weight, Lithium-ion batteries do not drop off in performance as their power drains. Unlike NiCd batteries, which show appreciable power loss toward the end of a charge, Li-ion batteries give almost full performance until the end, then boom — power is gone. All manufacturers recommend that you try not to completely drain Li-ion batteries. Li-ion batteries have no memory and can therefore be fully charged anytime without causing any cell damage. Li-ion batteries also hold their charge for a longer period of time. A NiCd battery may loose 20 percent of its charge per month while not in use but a Li-ion battery will lose less than 2 percent of its charge per month in storage. While this will mean little to daily users, this is a real benefit for tools that receive only occasional use and for homeowners and DIYers.
One great feature found on many of the new Li-ion cordless tools is a battery charge indicator or “fuel gauge.” A standard feature on Bosch, Metabo, Milwaukee, and Ridgid tools is an LED gauge which, when pressed, indicates the state of charge of the battery in hand. This is a feature first offered on some Bosch cordless tools a few years ago and a feature we would like to see on all battery-powered tools in the future.
Specially designed chargers are required for topping off Li-ion batteries — some manufacturers have fans in the charger and vents in the battery housing to keep the battery cool during charging, while others do not. Presumably the vents in the battery housing also help to keep the battery cooler during heavy duty use. Certainly a vented battery stands a better chance of dissipating heat than a sealed battery.
One last attractive feature of Lithium-ion batteries is that they can be tossed in the trash. All manufacturers do recommend, however, that these batteries be recycled in the traditional manner rather than disposed of in landfills.
As mentioned earlier, six major cordless tool manufacturers have introduced a totally new line of Li-ion powered tools. Let’s look at these in alphabetical order.
The new Bosch line is called Litheon and at the present time consists of the Bulldog, a 36-volt SDS-plus rotary hammer — similar to the corded version — and two 10.8-volt ultra compact drill/drivers (one stick grip, one pistol grip). The corded Bosch Bulldog has set an industry standard for a heavy duty rotary hammer and this new cordless model will surely do the same. These compact drill/drivers are very lightweight, extremely handy, and powerful. Bosch claims these little drivers can sink 100 3-inch screws before recharging. A fully charged unit will hold its charge for months when not in use.
Bosch plans to introduce a 36-volt circular saw, reciprocating saw, and hammer drill/driver in the coming months. Bosch has a three-year warranty on tools and two years on batteries.
DeWalt has introduced a 36v line of Li-ion cordless tools including the first 7-1/4-inch circular saw, reciprocating saw, hammer/drill, clever work light, and the only jigsaw in the industry. Future plans call for a rotary hammer and impact wrench. The entire line has been redesigned and offers many features you would expect from an industry leader. DeWalt offers a three-year warranty on all cordless tools.
Makita has introduced a line (LXT) of 18-volt Li-ion cordless tools that offer 18-volt power in a 12-volt weight package. This newly designed line consists of a 6-1/2-inch circular saw, hammer drill, reciprocating saw, and impact driver at this time. All tools have an LED light on the business end, a handy feature for working in low light situations. The new battery charger can charge NiMH and Li-ion batteries in 7.2 to 18 voltages. Makita offers a one-year warranty on cordless tools.
At this time, Metabo is the only manufacturer to offer its Lithium-ion technology in 12-, 14.4-, and 18-volt platforms for its existing lines of cordless tools. The new 18-volt platform consists of a 6-1/2-inch circular saw, reciprocating saw, and rotary hammer at this time. Additionally Li-Power batteries are compatible with the existing Air-Cooled line of Metabo tools. The new fan cooled battery charger can charge NiCd, NiMH and Li-Power batteries in all voltages.
Milwaukee V18 and V28
Milwaukee was the first manufacturer to introduce its Lithium-ion powered cordless tools more than a year ago, including a 6-1/2-inch circular saw, reciprocating saw, hammer drill/driver, impact wrench, flashlight, and a portable bandsaw. Recently Milwaukee introduced a line of 18-volt Lithium-ion batteries that are compatible with existing NiCd batteries.
While the cost of Li-ion batteries is higher than NiCd batteries, Milwaukee is betting that many present tool owners will want to try the lighter batteries without having to purchase a new tool platform. Milwaukee offers a five-year/2,000-charge warranty on its V28 and V18 cordless tools and batteries.
Ridgid recently introduced its 24-volt Xli series of cordless tools. This line is aimed at the 18-volt cordless tool user and offers about the same weight but longer run time. Included in this newly designed line are a 6-1/2-inch circular saw, reciprocating saw, and hammer drill/driver.
In the fall, Ridgid will introduce Max-Select tools that will have the ability to run either 18-volt NiCd or 24-volt Xli Lithium-ion batteries. Max-Select tools are sold without batteries or chargers. These must be purchased separately or in a Max-Select Starter Kit. The Max-Select line will consist of 6-1/2-inch circular saw, reciprocating saw, caulk gun, 3-1/4-inch hand planer, jigsaw, and impact driver.
Ridgid offers the most extensive warranty in the industry — a lifetime service guarantee.
If you are considering purchasing Lithium-ion platform cordless tools, expect to pay about 30 percent more than for NiCd or NiMH powered tools. There are some great deals out there in combo kits offered by all manufacturers. These kits typically contain all or most of the following — circular saw, reciprocating saw, hammer drill/driver, impact driver, flashlight, and carrying case. Prices range, depending on tools and manufacturer, from around $600 to around $800.
It is doubtful that Lithium-ion cordless tools will replace NiCd or NiMH technology quickly; too many users are invested in the older technology, and it works. But over the next few years, as the cost of Li-ion powered cordless tools comes down and older tools are taken out of service, Lithium-ion powered cordless tools will become much more common. Then again, some newer technology may be developed by power tool manufacturers and the industry will be taking a different course — hydrogen and fuel cells come to mind. As a rule, consumer electronics development often takes advantage of new technology quickly and power tools commonly follow over time.