battery backup
nounUK /ˈbæt.ər.i ˈbæk.ʌp/
US /ˈbæt̬.ɚ.i ˈbæk.ʌp/
A battery backup is a battery that keeps a machine working when the power goes out.
The computer stayed on during the storm because it has a battery backup.
OTHER MEANINGS
2. A device that stores electricity and takes over automatically when the main power fails.
The hospital's battery backup kept the lights on during the blackout.
3. Extra battery power kept ready to use if the main battery runs out.
He packed a battery backup for his phone on the long hike.
4. A copy of data saved on a battery-powered device in case the main copy is lost.
The camera's battery backup saved the photos when the card was removed.