Over the past year or so two major manufacturers of outdoor power tools, Black & Decker and Stihl, have introduced new lines of cordless tools powered by lithium ion batteries. In the case of Black & Decker, the new tools compete (for now) with an existing line of cordless tools powered by nickel-cadmium (NiCd) batteries. The new LSW120 lithium cordless leaf blower, for example, has about the same amount of blowing "oomph" as the well reviewed NS118 cordless blower, which uses a NiCd battery. ToolSnob.com describes the LSW120 cordless blower as "fantastic." (For more information about the LSW120, visit our comprehensive report on leaf blowers.)
Stihl's new line of 36-volt outdoor power tools with lithium ion batteries includes, so far, a hedge trimmer, a string trimmer and a leaf blower, although the leaf blower is not for sale in the U.S. yet. After trying out the string trimmer and leaf blower, Roy Berendsohn writes in Popular Mechanics, "It's the first cordless outdoor power equipment I've found that radically closes the gap between gas engine and cordless (or electric)."
Lithium ion batteries offer several advantages that experts say make them ideal for use in outdoor power tools like these. One is that they are lighter weight. To return to the example discussed above, the Black & Decker LSW120 weighs less (3.8 pounds) than the NS118 (4.8 pounds). Another advantage is that lithium ion batteries do not gradually lose power while you're using the tool; you can work at full power until the battery needs to be recharged.
Lithium ion batteries also require less maintenance than over other types of batteries. They don't self-discharge, so you don't have to recharge them every few months even if you don't use them; they will hold a charge for up to a year while in storage. In addition, they have no memory effect, so you don't have to completely discharge them before recharging them.
The downside is that lithium ion batteries are more expensive to manufacture, so they cost more to buy. The Black & Decker LSW120 costs only about $20 more than the Black & Decker NS118, but the batteries for Stihl's 36-volt cordless tools (which are sold separately from the tools themselves, as are the battery chargers) cost about $150 to $250. Stilh says their batteries will last through 500 discharge-recharge cycles, but since they have been on the market a relatively short time, no owner feedback about that is available yet.