DCF895L2 20V Max Cordless Brushless Impact Driver
DeWalt's 20V Max brushless impact driver features 3 speeds and is equipped with a battery fuel gauge indicator
By the time you read this, your local tool supplier will likely be stocking shelves with a new shipment of tools. These tools may have marketing lingo about a new “e-motor,” “BL motor,” or something similar. These terms refer to brushless motors.
To be fair, brushless motors are not a new technology, and some manufacturers already offer brushless tools, if only a limited selection. All signs now are pointing toward a bigger push, though. Makita and Hitachi are expanding their current offerings, Milwaukee and DeWalt are releasing their tools this spring, Bosch is aiming for a date later in 2012, and other manufacturers are undoubtedly working on their own updates.
Some manufacturers argue that brushless motors mean a reduction in maintenance because, just like the brake pads on a car, brushes wear out. How quickly the brushes wear out depends on how the tool is used.
According to tests conducted by the company, Milwaukee’s brushed-motor drills bored an average of 30,000 to 35,000 holes using a 1-in. auger bit before the brushes needed to be replaced. Their new brushless-motor drill bored 10 times as many holes before the team was satisfied enough to end the test.
Going brushless is not primarily about a reduction in maintenance, however.
According to Milwaukee’s numbers, you could drill 20 holes every day for nearly five years before needing to swap the brushes in a conventional electric motor. Even then, it’s usually a quick job costing only a few dollars in parts. The real story with brushless motors is in their increased run-time.
Run longer and maybe stronger
A brushed motor relies on a physical connection between the carbon brushes and the spinning rotor. In other words, the same brushes that are delivering electricity are creating drag. This drag wastes energy, and in a tool powered by a battery pack, energy is a precious commodity. No brushes, no drag. No drag, higher efficiency.
Milwaukee and Makita are claiming up to a 50% increase in run-time for a brushless-motor tool before recharging the battery. Heavy-handed tool users may see the biggest payoff in going brushless, because according to Milwaukee product manager Christian Coulis, “The harder you use a brushless motor, the better it’s going to perform compared to competitors.”
No drag also means that a drill or impact driver will boast a higher torque output, even under load—about 10% to 20% greater than the average brushed-motor competitor, according to publicized specs. Some brushless motors also incorporate electronic controls to help keep the output of the motor constant under a heavy load. According to Coulis, “The difference between peak torque and sustained torque on these tools is closer than Milwaukee has ever come.”
The price of progress
Don’t worry—your tools aren’t obsolete, and brushed motors aren’t going away yet. These conventional motors are relatively simple and inexpensive, and that carries lots of weight in a competitive, cost-driven tool market. In fact, for all but Festool—a company that has been focused on brushless motors for years—the new brushless offerings will be sold as premium alternatives.
A Bosch representative told me that brush less motors are costing the company about twice the price of the conventional brushed motors, but the hope is that the demand will help to reduce the price. Currently, the price difference to consumers for Makita’s impact drivers is around $40. I’m told to expect a difference ranging from $50 to $100 for Hitachi’s new impact drivers and drill-drivers, and Milwaukee is offering its brushless drill-drivers for a premium of about $30.
Bottom line: Aside from the slight upcharge, and assuming that the higher level of electronics doesn’t lead to unforeseen problems, brushless technology sounds like it will be a good step forward in cordless power tools. For more on brushed vs. brushless motors, see “How It Works” from FHB #226.