What is the term for the powered source used in a fire alarm system besides the main power?

The term for the powered source used in a fire alarm system besides the main power is "battery backup." In fire alarm systems, battery backups are essential for ensuring that the system remains operational during power outages or failures. They provide a reliable secondary power source that automatically activates when the main power supply is interrupted. This is critical for maintaining the functionality of alarms, notifications, and other safety features, ensuring that individuals can still be alerted to a fire emergency even when the primary power is unavailable.

In contrast, other terms like "primary power source" refer to the main power supply, while "generator" indicates a larger backup option that is not typically a part of standard fire alarm systems. "Auxiliary power" can denote additional power requirements but doesn't specifically refer to the backup function needed to support fire alarms during an outage. Therefore, "battery backup" is the precise term for this specific context in fire alarm systems.