We have been making then for close to 20 years know. We use the batteries that come with the 12 volt drills. This makes them potable and low powered. This reduces the chance burning the controls in the drill housing and damaging mechanisms that jam in early testing.. It also may not matter and we just keep doing the same way. All of our motors on our robots use Anderson power pole connectors.
The drill motors are great for projects. We use them on many off season projects. We add Anderson connectors and you can guess the power source for many of the projects.
Good to hear from you Sam.