Woodworker's Journal 2002-26-3, страница 47

Modern cordless tool battery chargers range from simple to advanced. Shown here: A Skil screwdriver with non-removable battery and a simple charger that the tool plugs into, Black & Decker's simple charger that replenishes the tool's removable battery packs, and micro-processor controlled Hitachi and Makita chargers with LEDs that display state of charge.

Improved Charger Technology

As cordless tool batteries have changed and improved over the years, so have the chargers that replenish them. While the cheapest bargain models still use built-in batteries and "wall-wart" style plug-in chargers, the standard chargers used with the majority of woodworking cordless tools that have removable batteries are more sophisticated, delivering higher current to recharge removable battery packs in about an hour. The simplest of these chargers use heat-sensing switches that turn power off when a battery is full.

The more advanced chargers use micro-processor circuitry to monitor a battery's condition. By using sophisticated thermal sensing to read a pack's temperature, these "smart chargers" can replenish batteries in as little as 15 minutes

while reducing the risk of damage due to heat — a battery's greatest enemy. If a pack is hot off the tool, charging doesn't begin until the battery cools down, and then it is charged to full capacity. The unit also shuts off if the battery overheats during charging, preventing costly damage.

The latest, most advanced chargers have more impressive features than ever. Makita's new Makstar" system uses the charger's CPU (computer brain) to read battery conditions via an EEPROM microchip built into each battery. The chip records the battery's history of use and transmits the data to the charger, which then optimizes the charging regime for peak performance and long battery life. While most chargers have at least one light that shows charging status, the multiple LED display on Makita Makstar chargers also reports the condition

The sophisticated Makita Makstar computerized charger actually communicates with the tool's nickel-metal hydride battery via a microchip in the pack. The unit's four-light display reports charging status, if battery is too cold or too hot to charge, if battery is being conditioned or is defective, and if the unit's built-in cooling fan is malfunctioning.

of the battery and when there is a charging problem. DeWalt and Makita both have chargers with a conditioning mode that optimizes battery performance. The companies says it gives users up to 20 percent more cycle life and more consistent run-time with every charge. The latest 24-volt DeWalt (and Makstar) chargers have built-in fans which force cool air through the pack, dispelling heat and extending battery life.

New Cordless Models and Features

What started with cordless drills has now blossomed into nearly an entire workshop's worth of battery powered tools, whose ranks now include: screwdrivers, drill/drivers, impact wrenches, hammer drills, power planers, circular saws, jigsaws,

These two cordless screwdrivers cover the voltage range — from the 3.6-volt Panasonic EY6225CQ to the more powerful, 12-volt DeWalt DW920. Both tools have removable battery packs.

DeWalt's three-speed gearbox drill allows the 18-volt model DW980 drill/driver to spin small drill bits or driver bits at up to 2,000 rpm — significantly faster than other cordless drills with only two-speed gearing.