Hold down the volume button until you hear the Relay beep
When you hear the Relay beep say "Battery" and then let go of the volume button
The Relay will announce its current battery level
The Relay app
In the Relay app, tap on the Direct Chat for the Relay in question.
Tap on the battery icon near the top of the page
A pop up will appear indicating whether the Relay is charging or discharging (off the charger) along with the current battery level of the device.
At times the Relay app may not correctly show the Relay's battery level as the data has not been refreshed. Closing and reopening the app refreshes the information the app is recieving, as the data for the battery may become stale.
The LED Ring
The LED ring on the Relay will also indicate the Relays battery level when the talk button is activated, allowing you to see the battery level during use.
A full charge will display a completed white ring, a 75% charge will display 3/4's of the lighted white ring, 50% will show half of the right lit, and so on.