DeWalt XR cordless tools are not new. Yet the question is often raised: are DeWalt XR tools worth the extra cost? The answer can only be yes. This is because of the superior efficiency and durability of the DeWalt XR brushless motor. The real distinction to be made here is that of brushless vs brushed motors and why are DeWalt XR tools more expensive than standard 20V MAX tools.
The questions around brushed vs brushless motors is not unique to DeWalt XR 20V MAX cordless tools. All of the major power tools brands have introduced brushless motors for their top models. The main reason for this is to extend the battery working time. In some cases, battery autonomy (or working times) can be improved by up to 60% using a brushless motor over the old-fashioned brushed variety. Though, realistically, one should expect around a 25% improvement in efficiency when comparing Brushless vs brushed electric motors.
Apart from improved battery time, brushless technology has several more advantages. Tools with a brushless motor, like the DeWalt XR range, last longer. The motor is able to move faster, improving the RPM. A brushless XR motor requires basically no maintenance, reducing downtime, hassle, and service costs. Even though Brushless DeWalt XR tools are more expensive than conventional 20V MAX tools, professionals and DIYers will mostly agree that the advantages of using DeWalt XR tools are well worth the investment.
This article is going to explain brushed vs brushless motors and provide a general discussion on DeWalt XR 20V MAX tools. The 20V MAX range is, arguably, the most popular in the world. This has a lot to do with the expansive range of products. There over 200 of them. The big advantage is a single battery platform for the largest selection of cordless tools. One battery for all your tools is convenient and cost-effective. You don’t need a bunch of different batteries and chargers. The same 20V MAX battery (in wide variety of sizes) can be used for all 20V MAX tools. This means that whether you’re using the improved XR tools, or the cheaper 20V MAX tools (with a brushed motor), you can use the same 20V MAX battery throughout your cordless tool collection.
A more recent addition to the DeWalt repertoire is the FlexVolt (20V/60V) battery. The FlexVolt battery can power any of the 20V MAX tools, as this is a dual voltage battery, able to supply 20V or 60V. Along with the battery, DeWalt have introduced a range of highly efficient 60V tools. The FlexVolt battery is designed to supply either 20V or 60V tools. There are also a few 120V cordless tools, using 2 X 60V MAX FlexVolt batteries connected in series. These are, in my opinion, the best cordless tools on the market. They are quite expensive, but they are simply incredible.
You can read more about the DeWalt 20V MAX vs 60V MAX topic in this article: DeWalt 20V MAX vs 60V MAX FlexVolt ǀ Do cordless tools need the extra volts?
The latest development from the DeWalt R & D guys is the DeWalt Atomic range, launched in 2019. This is an extension to the, now popular, DeWalt XR lineup. Basically, they’ve taken the concept of a brushless 20V XR tool and improved on it. The greatest advantage is the lightweight, compact design of the DeWalt Atomic tools. DeWalt marketeers claim the Atomic Drill/Driver (the first DeWalt Atomic tool to be launched) has 13% more power and delivers 21% more torque. It is also 25% more compact.
How does a DC electric motor work?
In order to understand what a brushless motor is, and why it’s better than a brushed motor, we first need have a basic understanding of the latter.
The brushed electric motor was the first to be invented, preceding the AC (inductive) electric motor. The concept of an electric motor dates back to the early 18th century. Though it was in 1886 that William Sturgeon invented the first practical DC electric motor, able to sustain a constant speed under variable load. The AC induction motor was invented by Nicola Tesla in 1888.
All electric motors convert electrical energy into mechanical energy by implementing opposing magnetic force. This is the scientific principle of magnetic polarity either attracting or repelling. When magnets are faced with the same poles together (north to north, or south to south), the magnetic force will be opposed. This causes the magnets to move away from one another.
By using an electromagnetic rotor (or armature), held in position by bearings, and fixed magnets (stator or field windings) around the rotor, the opposing magnetic forces cause the rotor to spin. In order to supply electric current to the rotor, brushes conduct electricity to a commutator.
The commutator is a segmented disc at one end of the rotor. Each segment conducts current to a copper winding, producing a magnetic field. These windings are designed to alternate the polarity from north to south as the rotor spins. In doing so, there is a constant repulsion between the rotor magnets and stator magnets.
Brushes were originally made of copper wire, resembling a small copper brush. Modern brushes are made from graphite or carbon, which is more durable. The brushes remain in constant contact with the commutator, which is spinning at several hundred (or thousand) RPM. This generates friction. The constant friction between the brushes and commutator, generates heat and places strain on the commutator bearing. Carbon dust is also produced as the brushes wear down.
The cumulative effect of all these factors means that a brushed motor is less efficient, as the friction reduces the ability of the rotor to spin freely. Heat also reduces electric efficiency and the lifespan of the motor. Under high torque conditions, the brushes will arc, producing sparks that further reduce efficiency and durability. Carbon dust, produced by friction on the brushes, requires frequent cleaning, increasing maintenance. When the brushes wear beyond their usable life, they need to be replaced.
What is a brushless electric motor?
The brushless electric motor was invented to overcome the drawbacks presented by brushes and the commutator. Without brushes, friction is eliminated. This makes the motor more efficient, by reducing heat and the energy loss associated with friction. Maintenance is virtually eliminated, and the motor is lighter, as the extra weight of brushes and the commutator are no longer a factor.
The first brushless electric motor was the brainchild of inventors, T.G. Wilson and P.H. Trickey. Their prototype brushless DC motor, first seen in 1962, used solid state commutation. This replaced the previously used commutator and brushes. During the 1970’s the electronic revolution brought about more advanced transistors, making brushless motors more practical. By the 1908’s a commercially viable brushless DC motor became a reality.
A brushless DC motor utilizes an inverter or switching power supply to convert the DC current into 3-phase alternating current (AC). The DC electric motor is usually known as a synchronous motor because the frequency of the converted AC supply is synchronized with the rotation of the rotor shaft. Although an asynchronous, induction motor can also be used for this purpose. The DeWalt XR, and other brushless battery-powered tools use a variable-frequency (synchronous) 3-phase motor as this allows for the best speed control, using digital technology.
Unlike a brushed motor, using an energized rotor (electromagnet) and fixed magnet stators, the brushless motor uses the opposite principle. The rotor has fixed magnets attached to it and the outer, stator, produces an electromagnetic force. Sensors detect the position of the motor and switch the polarity of the stator magnets, depending on the rotor polarity. Electronic management also ensures that torque and speed remain constant. This allows for greater control over the motor under varying working conditions and ensures the best energy efficiency.
Are DeWalt XR tools worth it?
There can be no doubt that DeWalt XR tools are the best from the brand. To boot, the DeWalt name carries some weight. That’s not to say that other top power tool brands, like Milwaukee, Makita, and Bosch (to name only a few) are not equals in the field of efficient brushless motor technology. Visit any power tool discussion forum and the debate over DeWalt vs Milwaukee will usually dominate. I will not deny that Milwaukee Fuel tools are truly superb, and feel much the same about Makita LXT cordless tools. In the end, whether it’s DeWalt XR tools, or any brushless corded tools from a reputable brand, the advantages of brushless technology remains the same.
When comparing DeWalt XR tools (18V or 20V) to their cheaper tools, using a brushed motor, the advantages can summed up as follows:
- Improved battery time
- Longer tool life
- Improved torque and RPM
- Less maintenance
- Digital management system
- Lower power to weight ratio
This offers some compelling reasons to pay extra for DeWalt XR tools.