Ring doorbells require a battery even when they are hardwired. The hardwired connection simply trickle charges the battery. However, the Ring Video Doorbell Pro is completely wired and does not require a battery pack. It's important to note that the exception to this is the recently released Ring Video Doorbell Wired (2021), which requires a Ring Chime, Ring Chime Pro, or Amazon Echo/Alexa device in order to have an audible internal ring