What you guys were suggesting was not quite clicking in my head until I dug up this video:mech18 wrote: ↑Mon Oct 29, 2018 10:00 pmI agree I think those batteries would work. You could use with a DIY adapter but easier with a pre-built unit given the center pin voltage requirement. If I were to use them I would connect the dc/dc converter to a usb adapter for the battery such as this:
https://www.amazon.com/Power-Source-Mil ... 01C3FRFO8/
Just open it and wire directly to the primaries for the battery. You could even leave the usb port active for your phone. I have sacrificed something similar to use DeWalt 20V max batteries for floundering lights.
Good luck and post pics if you do it.
https://www.youtube.com/watch?v=GnuvRopt74g
Working overnights sometimes really messes up my ability to fully absorb what I'm reading.

I also dug up this project. This guy used a 3D printer to create a housing for a DC power station to use Ryobi 18 volt batteries for DC and USB power, but the concept should be adaptable to pretty much any tool battery.
https://hackaday.com/2020/02/20/diy-pow ... s-to-work/