More cordless drills and cordless tool kits feature lighter or longer-running lithium-ion cells instead of nickel-cadmium batteries. But our tests of cordless drills and tool kits show that lithium cells can die an early death if you aren't careful.

During our tests, several lithium batteries from multiple brands couldn’t be recharged after we ran them down to full discharge. So using every last minute of run time is a potentially expensive mistake, since replacement cells can cost more than $100. You can also shorten batteries’ life span if you let them sit longer than six months with a full charge, manufacturers say (store them at a 50 percent charge for best results). These situations make built-in charge indicators a plus for lithium batteries. But among the top lithium-powered drills and the kits we tested, only the highest-scoring Ryobis have them.

Familiar names such as Craftsman and Skil are also pushing lithium-powered screwdrivers that cost about $40, weigh 1 pound or less, and make tempting gifts. But after months of drilling holes, driving screws, and rip-sawing lengths of pine beams, we found that several kits and some drills that didn’t make our Ratings of cordless drills and cordless tool kits (both available to subscribers) are a poor value. We also found some heavily promoted cordless tools to be light on performance. Here are the details:

Peter Sawchuk evaluating drills
TORQUE TEST  Our tester uses a special meter to evaluate all cordless drills under the same conditions.
Photo by Michael Smith
When kits don’t pay
Most cordless tool kits include a drill, reciprocating saw, and circular saw for $300 to $500. Two from Black & Decker and Skil seemed like a bargain at about $200. But both were unimpressive, especially their reciprocating saws, used for taking down walls and for other demolition. The Black & Decker saw was slow and weak, and the Skil saw made seating and locking the blade a challenge. Their circular saws lacked comfortable handles and had short run times.

A big name brings little to the table
DeWalt says its new compact drills bring the toughness of a contractor-grade drill to smaller, weekend projects. But the DC720KA, $219, and the DC730KA, $180, drove fewer fasteners than many less-expensive models before they needed recharging.

When paying less buys less
Most lithium-powered drills cost $180 or more. Ridgid claims better balance for its R82007, $130, but our testers found it nose-heavy and awkward. Skil heralds its 2815-02, $100, and 2510-02, $90, as lightweight and powerful cordless tools. But we found those drills light on power and run time.

Small drills that do little work
Skil advertises compact performance for its 2362 cordless screwdriver, $40, and Sears says its similarly priced Craftsman 11398 offers power with longer run time. Yet both were slower and wimpier than other miniscrewdrivers. A better bet: Spend $10 for a good hand screwdriver set or $20 for a good push drill. Read our expert advice on smart, safe ways to use a drill.