How Do You Know If Internal Batt Is Dead

[lufc]

how do you know if your backup battery is dead my blue angel is dead when i put it on charge with no battery the red light is on but if i connect a battery the light goes out its not the main battery cos i have tried 3 does the red light show that the back up battery is flat if you do not have a main battery fitted hope you understand that thanks

[Willuknight]

put a fully charged battery in it and leave it overnight


then charge it for another 4 hours, then take it off charge and check what the battery pane in the settings panel shows.