Tools: Recharging Batteries for Cordless Tools – On the House

Tools: Recharging Batteries for Cordless Tools

By on July 7, 2015

Our dad loved to work with his hands. He especially loved woodworking projects. Dad’s favorite place was his workshop. We knew it simply and affectionately as “the shop.”

Dad’s shop was chock full of really neat 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 seemed as extensions of dad’s arms and hands.

As young men, the wares turned out of his shop awed us. Thus, we learned early on to have a healthy respect dad’s tools. We realized the importance that good tools played in making a job simpler and more enjoyable.

Piles of sawdust, wood shavings, stain saturated rags and paint-splattered cans were the prelude to something wondrous. Dad epitomized the cliché; “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 objects d’art.

We recall vividly the tired old vintage console radio that he converted into a credenza for mom’s fine crystal and china. There was any 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 tool. Such tools didn’t exist in his heyday. We are certain that he would delight in the convenience and power of battery-operated cordless tools. He would be 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 cordless tools. By the way, this column was written on a computer with a rechargeable battery aboard an aircraft some thirty thousand feet in the air. Technology; ain’t it great!

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 charges 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! Moreover, 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 occurs when recharging a nicad before it is fully discharged. Accordingly, it may begin retaining its charge for shorter and shorter periods. Hence, short memory syndrome.

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.

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