Our dad loved to work with his hands. He especially enjoyed woodworking projects. Dad's favorite place was his workshop, which we knew simply and affectionately as "the shop."

The shop was plentifully supplied with fascinating things. As young boys, we marveled at the elaborate contraptions that bedecked this cavernous space. A bench grinder, vise, drill press, table saw and an assortment of shiny chrome power tools. All seemed to be extensions of dad's arms and hands.

The wares turned out in his shop awed us. We realized the importance that good tools play in making a job simpler and more enjoyable.

Piles of sawdust, wood shavings, stain-saturated rags and paint-spattered cans abounded. Dad believed that one man's rubbish is another man's riches. He had a knack for transforming an old piece of furniture that he'd retrieved from the local dump into art objects.

We recall the tired old vintage console radio that he converted into a credenza for mom's fine crystal and china. There was an almost endless stock of cabinets and bookshelves, tables and chairs, beds and desks that found new life in dad's shop.

One reasonably modern type of tool that dad didn't have in his shop was the cordless variety. Such tools didn't exist. We are certain that he would have delighted in the convenience and power of battery-operated cordless tools. He would have been especially pleased at not having to fumble with power cords, extension cords, and the need for their frequent replacement.

Although cordless devices have been around for a while, their popularity has reached new heights. Driver drills, leaf blowers, circular saws, chainsaws, string trimmers and even cordless lawn mowers are a few of the most notable. In fact, this column was composed on a computer with a rechargeable battery aboard an aircraft some 30,000 feet above the ground.

Thanks to improved battery technology and the advent of powerful lightweight motors, the best cordless units nearly match the power and performance of their corded counterparts. The latter must be plugged into regular household 120-volt alternating (AC) circuits.

Three features distinguish cordless units from corded models: a direct current (DC) motor, rechargeable batteries and a battery-recharging device. Periodically the cordless device or its battery (depending upon configuration) must be returned to the charger to replenish battery life.

Some cordless appliances and tools operate on nickel-cadmium batteries (nicads), either individual cells or a battery pack consisting of as many as 20 cells. Each cell provides direct current at about 1.2 volts, approximately the same as an AA penlight battery. Battery packs slip directly into the appliance or tool or have snap-on terminals.

Even though nicad batteries can be recharged up to 1000 times before wearing out, undercharging shortens their life. A new nicad battery should be fully charged before using a new cordless tool or appliance.

Recharging a battery requires two items: a transformer and a diode rectifier. The transformer reduces voltage from 120-volt current to the much lower voltage required by rechargeable batteries. The rectifier located either in the charger or in the appliance or tool converts AC current to the DC current that batteries use.

During the charging process, some electricity is lost as heat, which is why chargers get warm as they operate.

The length of time that it takes to recharge a battery depends on both its condition and the amperage supplied to the charger. "Trickle chargers" work at very low amperage and may take up to 16 hours to fully recharge a battery pack. On the other hand, a fast charger uses much higher amperage and can do the job in as little as 15 minutes.

In either case, be sure that the charger being used corresponds to the tool or appliance. This ensures that the voltage and charging rate are correct for the batteries.

Don't overcharge. And, don't store a battery pack or appliance in the charger all the time unless specifically recommended by the manufacturer.

Some batteries share a condition that we have, "short memory syndrome." This condition is a result of recharging a nicad before it is fully discharged. It might begin retaining its charge for shorter and shorter periods.

Prior to tossing a short memory battery pack, attempt to restore its memory by operating the device until the battery is completely exhausted. Then recharge the battery pack fully, repeating this cycle several times. If the memory doesn't improve, replace the batteries.

New types of rechargeable batteries, more potent than nicads and therefore not subject to short memory syndrome, are increasingly being used in cordless equipment.