Doorbell 2ndGen HardWired but loosing battery

Greetings, I have a 2nd Gen doorbell, used this battery-only at first because there was no way to hardwire it. I recently moved to a new house and this house has a transistor/wired connection, making it easy for me to hook it up to my Ring Doorbell. So, i took off the button of the old doorbell and used the wires to connect them on my Ring Doorbell. In the settings it does say " wired ' as a powersource so i was happy; no more changing batteries every 2, 3 weeks... Now,.. 3 weeks down the road i have seen the battery level going up gradually, like 1% each day, making me think this is more like a trickle-charging situation than rather a full-blown wired situation. So.. when i moved and placed my Ring Doorbell on the wall, my battery was around 20%... in the 3 weeks ive been monitoring i have seen the battery level go up towards 41%, but all of a sudden, in the last, lets say 7 days the battery went lower and is now 10%.......while it is wired!!?... Why does it at first (slowly slowly) charge, but now suddenly is heading towards a shut-down due to no battery? Why is "wired" not making the battery go uo to 100% and stay there? I did not change any setting, WIFI RSSI is -50, i do have all options on full/on max (120secs monitoring etc), which might drawn more power, but why did it charge slowly all the way up to 40's and is now almost down to 0?? Anyone can explain what i do wrong? edit- for some reason i might expect a " you can charge it again the old way " answer as a solution, but i can already tell that this aint much of a solution. Unscrewing the Doorbell, then disconnecting it from the wired situation (after taking down the breakers to avoid electric shocks), then connecting it to an adapter, charging it upto 100, which takes half a day (no doorbell at that time), to connect it/wire it again while there is a wired-option.... hope there must be some explanation for this...