I finally bought some of the Loco Genie equipped locomotives offered by Model Power so I could play around with the system. Here's a Model Power 0-4-0 Shifter that I've been working on. I used the Loco Genie out of the 0-4-0 Dockside. The battery is an 3.7 v 18350 which are commonly used in vaporizers. I'm using a Pololu 12v regulator to step the voltage up. I wanted to convert the dockside but couldn't figure out how to get everything in there but will work on it. So far very happy with how everything is working. These are the first DCC or sound equipped locomotive that I've ever had and really like having sound.
Here the Model Power Plymouth diesel that I've converted. This was easy and had it running on battery quickly as all I had to do was cut the wires to the wipers and run wires to a trailing car. By the way, I learned these diesels are oversized and might work well for On30.