Not sure how the charging should work at all. In a normal (analog, wired) setup there is no 8/12/14V appears at the point of the old doorbell connection point as it breaks either the + or - wire. 8V (in my case) only appears at the Ring when you close the circuit by pushing the button.
The only way I could get 8V at the wires where I should hang the Ring Video Doorbell if I make a short at the ring, as such disabling it. But in this case I could not use it, right?
So at this moment what I can measure on the point where Video Doorbell should be hanged is 0V, which is not enough for charging 