So I originally bought a combo set that included the battery, controller, angle grinder and rotary tool. I am the creator and this set looked like a portable set that I could use. The concept is great, but Worx needs to rethink the speed controller. Outside the box, the rotary tool and grinder constantly stop at the slightest resistance, and the control box has to be cycled to reset. I'm not the only one with the problem so it seems to be ubiquitous. I sent the kit back and then decided to just order the tool and modify it. Turns out the problem is NOT in the tool itself. This is a Worx electronic speed controller. If you're a DIY enthusiast, you can easily buy a cheap three-phase electronic speed controller from Amazon and build your own control box. I 3D printed a Dewalt battery mount (I use Dewalt for everything else) and connected 20V to an Amazon speed controller. I ripped out the ESC, which is actually not on the control box but in the tool itself, and connected it to the Amazon ESC. The tool now has BALLS. Never stops, grinds, cuts or grinds anything. The brushless motor is powerful, I wish the electronics were as good as the motor. Buy with caution unless changing.