Tool Talk: The second generation of 24-volt batteries

Twenty-four volt cordless tools have been around for a few years and the major manufacturers have developed a “second generation” of batteries and chargers to help correct heat problems that have come to light over time. Before we get to the new stuff, let’s quickly review what makes a good cordless tool battery.
The most popular type of cordless tool battery in use today is the nickel cadmium, or Nicad for short. In part, this is due to the longer life cycle of Nicad when compared to nickel metal hydride (NiMH) and the futuristic lithium ion batteries. Another reason is the cost of batteries for cordless tools — Nicad remains less expensive than all other types.
At this time only Makita offers NiMH batteries in 24 volt cordless tools. It is felt that NiMH batteries provide a longer run time between charges than Nicad batteries while at the same time being lighter. NiMH batteries are also said to be less harmful to the environment if they are tossed in the trash. They are, however, more expensive than Nicad batteries.
Lithium ion batteries may have a seat in the cordless power tool platform in the future. These batteries are popular in cell phones at this time but need more development before they can be offered for power tools. Nevertheless, Lithium ion batteries are lighter than NiMH batteries, last longer, and take up less space. It will probably be a few years before Lithium ion battery cordless power tools are fully developed to the point where they are practical.

Bosch 24 volt batteries
Bosch Power Tools now offers a unique Nicad battery on its 24 volt SDS cordless drill/hammer drill. The battery is equipped with a battery charge condition indicator. This clever gauge is activated while the tool is in use and indicates the level of charge in the battery by illuminating up to five green lights — fully charged.
When only one green light blinks, the battery is nearly discharged and must be recharged. When the tool is not in use or if the battery is out of the tool, the gauge can be activated by pressing the “on” button. Hopefully we will see more of this handy feature from other cordless tool manufacturers in the future.
This Bosch 24 volt battery can only be charged in the BC016 charger, which is not compatible with other 24 volt batteries in the line. Charge time varies from 15 to 26 minutes depending on ambient temperature, battery temperature and state of discharge.
Red and green lights on the charger indicate trickle and fast charge mode respectively.

DeWalt 24 volt batteries
DeWalt has recently introduced a second generation 24 volt Nicad battery for its line of cordless power tools. These Nicad batteries differ from their predecessors in that the battery case is now vented to allow heat to dissipate more quickly. Users of the first generation 24 volt tools are aware that the batteries get warm quickly and run time seems to diminish. The new
batteries have vents that help to cool the unit while in use, presumably extending run time.
A new charger is also available with the new 24 volt XR+ batteries — the DW0246. While this charger and the older DW0245 both have a reconditioning mode, the newer unit has the improved feature of an internal fan. The fan cools a battery before and during charging. This should translate into quicker charges in the field and longer battery life.
The DW0246 battery charger for 24 volt batteries can only be used with these units — it will not charge 12, 14.4, or 18 volt batteries — but it does an excellent job of charging 24 volt batteries in one hour. It also allows users to Tune-up™ their batteries, providing up to 20 percent more cycle life and more consistent run time on each charge. DeWalt recommends a tune-up every 10th charge, accomplished by pressing a special tune-up button on the charger.
All cordless tools in the DeWalt 24 volt system can also use an AC/DC converter — a first in the industry and available as an accessory — that combines cordless convenience with a continuous power supply. This patented technology allows you the flexibility of buying the power of a 24 volt tool, and then using it either as a cordless tool or as a corded tool. The AC/DC converter (DW0247) is the same size and shape as the 24 volt battery, and can be used in place of the battery — maintaining balance — and comes with a 9-ft. power cord. It also has an internal fan to help cool the unit during use. This system gives users the security of knowing they will always have a back-up system.

Makita 24 volt batteries
Makita offers the 24V MakStar system, which features the latest in battery technology, Nickel-Metal Hydride (NiMH). Two different size batteries are available in the 24 volt platform: a 3.0 Ah battery that has high power and incredible capacity, and a 1.7 Ah with high power in a light, compact design. Both are environmentally friendly. These batteries feature a completely new battery cell design that delivers extreme power and also improves heat dissipation of the battery. To further enhance the cooling of the battery, each battery cell makes contact with four heat dissipation plates.
To ensure a battery achieves cooling while being charged, Makita has developed a patented Forced Air-Cooling System with a built-in fan that circulates continuous cooling air from the MakStar Charger throughout the interior of each battery cell for maximum battery life and to minimize charging time. To minimize the charging time and any excessive charge applied to the battery, a built-in, dust proof memory chip is installed in each battery and it records the history data of each battery cell. This data is transmitted to the MakStar Charger to determine the optimal path for the best charge. Built to withstand rigorous use, each battery has 20 individual battery cells that are completely protected with three layers of molded shock absorbing material.

Equipped with a built-in central processing unit, the computerized digital communication system accurately detects the history of each battery by reviewing the charging and discharging patterns. By adding the Refreshing Battery Adapter (accessory item No. 193208-4) to the charger, each battery cell that has not been activated now can be conditioned and optimized. Fully optimized batteries perform longer.
Cordless power tools have become more powerful with the introduction of the 24 volt platform several years ago. Professionals have come to rely on these tools for demanding applications. With the introduction of the next generation of 24 volt batteries these tools are even more dependable and last longer. Twenty-four volt cordless power tools now rival corded tools in performance and, of course, they can be used anywhere.

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