Ripped from the pages of Popular Science February 2008

Bring a dead electric screwdriver back to life in seconds by adding quick-charging supercapacitors.

It’s the do-It-yourselfer’s version of Murphy’s Law: Every time you need to sink some tough screws, the battery in your cordless screwdriver is dead. So you do the only thing you can: plug the screwdriver into an outlet and endure the several hours it takes to recharge. But why wait all day? Replace those plodding rechargeable batteries with large-storage supercapacitors that power up via your computer’s USB port, and you can shorten recharge time to less than a minute and a half. Supercaps both store and deliver energy quickly, so you won’t get nearly the endurance of a battery, but each charge will get you through a couple of screws—perfect for quick tightening jobs. Coleman now sells a fast-charge model that lasts a little longer, but our DIY version is half the cost. Now your only problem will be figuring out what to do with all that extra time on your hands.—Dave Prochnow

Before closing the screwdriver, check all connections with a multimeter while test-charging and discharging the capacitors. Modding a screwdriver in this way may void its warranty.

COST: $41


See the February 2008 issue for step-by-step building instructions.