Simpler is usually better, and simpler is definitely the case with the new wave of brushless cordless tools now hitting the market. I got the chance to run performance tests on the first wave of Milwaukee brushless drills to hit the Canadian scene beginning a few months ago. I also got to tear these tools apart to see what they look like inside. I discovered that brushless technology offers superior performance and that’s the main reason I expect it will completely displace the kind of brush-style motors that have been in all your cordless tools since day one.
Brushes are spring-loaded blocks of carbon that press against the revolving internal parts of an electric motor. They’re part of a mechanical system that creates the revolving magnetic field that makes electric motors spin – and they’ve served the world well for more than a century. However, brushes waste energy and wear out in time. Side-stepping these problems is where brushless motors make all their gains.
Brushless Motors
Brushless motors use integrated circuits to electronically do what mechanical springs, brushes and wear-prone parts used to accomplish. Pull
the rotor out of a brushless motor and all you’ll find is a metal cylinder made of laminated layers of thin steel. From a manufacturers point of view, brushless motors require fewer mechanical parts. That’s one reason why I expect they will become mainstream.
The big selling point for contractors is that brushless tools are supposed to generate something like 50% more work from a given size of battery. Also, brushless motors last as much as 100% longer than brush-style versions before wearing out.
Brushless tools haven’t been out long enough to verify the claims for longer life yet, but with no friction and internal brush wear, I’d be surprised if they didn’t offer big durability gains.
To check out claims for increased brushless performance, I put three drills to a challenging test. I fitted a brand new 9/16-inch diameter ships auger bit onto two brush-style drills – the 20 volt DeWALT DCD989 and the 18 volt Makita BHP454 – and a brushless drill – the 18 volt Milwaukee FUEL 2604. I bored as many 10-inch deep holes in the ends of hard maple logs as I could on a full charge. Each drill was allowed to rest after every five holes were bored, to simulate real-world conditions. I recorded figures for total inches drilled and speed of drilling in multiple runs, then averaged the results to eliminate unseen differences in wood or bit performance.
The bottom line is clear. Brushless motors do operate significantly more efficiently than brushed. This translates into cooler drill performance, more work accomplished for a given amp-hour of battery charge and measurably greater drilling speed. To see how I ran the test and the particular details of how each tool performed, check out my video.
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