A fire alarm system consists of numerous components located in different parts of a building. These components are all connected to a control panel, and they are sustained by a main power source, which is typically provided by the electricity lines in the building.
This central power source is the Alternating Current source or AC. In cases where the AC source is unavailable, due due to power blackouts or other malfunctions, the fire alarm system will operate on a reserve power supply, which is the DC source or Direct Current source. This is provided by fire alarm batteries that serve as a back-up power source for the system.
You might be thinking, There is hardly ever any power outage in my building, so do I really need to have reserve fire alarm batteries? The answer is yes, you absolutely do.
Even if you've never experienced power failure in your building before, you will not be able to predict when it will happen, so it is critical to have back-up fire alarm batteries, and to periodically test these fire alarm batteries to make sure that they are functioning well.
Constant monitoring of the fire alarm control panels will notify you regardless of your fire alarm batteries are in need of replacing. In a lot of fire prevention schemes, there will be a green light on the control panel indicating that your system is running on the regular electrical power supply. During this time, the fire alarm batteries will be recharging.
In case of unavailable AC power, your system will automatically get power from your fire alarm batteries, in which case the lights on the control panel will change to red.
Although most fire alarm batteries are rechargeable, you will still need to replace them ever. Some systems notify you when your fire alarm batteries need to be replaced by issuing a series of beeps or flashing a warning on the control panel screen. Once your fire alarm monitoring team sees this warning, it is important to replace the fire alarm batteries right away.
There are also some components of the fire alarm system that, although they are still connected to the other fire alarm components in the system, use their own fire alarm batteries even when the system is running on the building's electrical supply. These fire alarm batteries are independent of the main power supply.
Ideally, the performance of fire alarm batteries must be checked every six months. Doing this will ensure that whenever a fire emergency does arise, you will have enough power to keep your fire alarm system activated, even if the main power supply is cut off.