Power supply

I’m getting power to the piece that the doorbell pro attaches to that’s on the wall. Getting 18.9v. But when I put the ring on the thing and check device health it still shows battery and the battery health still drops over time.

If your original door bell chime is a solid state electronic chime rather than an older style electro-mechanical chime, there is not enough current available to charge the ring doorbell. If your existing doorbell is DC powered rather than AC it is not compatable with Ring which needs AC.

If your door bell plays a melody rather than a ding-dong sound, it is an electronic chime. Check the Ring set-up instructions, there is a procedure for solid state electronic chimes. If it is an electronic chime it may be necessary to replace it with an electro mechanical chime and AC transformer

https://support.ring.com/hc/en-us/articles/115003008663-Ring-Video-Doorbell-2-Chime-Kit-Compatibility-List