Wired Ring (Gen 2) with mechanical chime - ring in power cut?

I have installed my Ring (Gen 2) video door bell all fine. I have told the app there is a mechanical chime and the chime works when the button is pressed (it didn't before changing settings in app). However, if the mains is off, even though the Ring has a battery and the light shows blue, the Ring does not work. Shoudl the Ring work on battery, if there is no mains power? TIA.