Brushless motors: The newest cool tool advance
Brushless motors are the newest things in cordless tool technology, and while you may have seen some in the past, you’re going to see a whole lot more in the immediate future.
If you see a cordless tool marked with the words “BL motor,” “e-motor” or something similar, it uses this new technology.
The new brushless motors promise reduced maintenance, and longer and stronger run times. A motor with brushes relies on a physical connection between the carbon brushes and the spinning rotor to conduct electricity and activate the tool. That connection creates friction as the rotor is spins, which not only wears out the brushes but also creates drag and wastes energy.
During testing of its new brushless motors, Milwaukee bored an average of 30,000 to 35,000 holes with a 1-inch auger bit before the brushes needed replacing. Milwaukee’s new brushless motor bored 10 times that many holes before the testing team basically got bored and halted the test.
The real benefit to a tool with a brushless motor, however, promises to be increased run time. With no brushes creating drag, these new tools boast much higher efficiency. Milwaukee and Makita claim up to a 50 percent increase in run time for brushless motors before recharging is necessary. No drag also means a drill or impact driver will deliver higher torque output even under load.
Manufacturers are claiming 10 percent to 20 percent greater torque than the average brushed motor, and some brushless motors also have electronic controls to keep output constant under a heavy load.
Brushed motors aren’t going away any time soon. They are a simple and inexpensive technology, and most contractors can replace their own brushes in the field in just a few minutes and for a few dollars.
The new brushless tools rely on sophisticated computer circuitry to alternate the polarity of the electromagnets, which in turn creates rotation. That could create problems for quick repairs in the field.
Still, the benefits of the new technology are hard to ignore – more power and fewer recharges mean increased production, and assuming the computer circuitry is tough and reliable, maintenance should be greatly reduced. The new tools will cost $30 to $100 more than a comparable brushed tool, but manufacturers say as demand for the technology increases, the price premium will go down.
—By Rob Fanjoy