Batteries are typically used within the system control panel and other auxiliary power supplies connected to the system as a secondary (backup) power source should the mains supply fail.
There are minimum operation durations set in both BS 4737 and the newer BS EN 50131 standards that cover their use. there are also guidelines for replacement of the batteries covered by these standards and also inspectorate Codes of Practice.
The backup battery
The backup battery is a vital component of any intruder alarm system, working 24/7 in the background to help keep the system running. It is however a common cause of the dreaded 3am call-out for alarm companies. For systems with maintenance contracts it is often due to premature battery failure from environmental causes (batteries don't like heat or water). For systems without maintenance contracts, this is because it is also the most overlooked part of the system as it is cooped up inside the control panel or remote power supply. So it remains out of sight and very much out of mind. That is, until it fails and causes the system to alarm.
The batteries used in the control panel are a sealed lead-acid (SLA) rechargeable type - so you need to get the correct voltage and amperage rating i.e. 1.2 or 2.1 or 3.2 or 7.0 amp-hours (Ah) etc, that suits the control panel and system requirements.
Standard SLA battery sizes
The most popular battery sizes rated in ampere hours at 12 volts are:
1.2 Ah
1.9 or 2.1 Ah - slim form with terminal on top at each end.
2.8 or 3.2 Ah
7.0 Ah
12.0 Ah
17 Ah
Larger sizes are available. Picture on right shows 7Ah unit
SAFETY WARNING
These types of batteries can be dangerous: Please store carefully with the terminals covered. Shorting out a battery can cause it to overheat, expand, blow off excess pressure, smoke and sometimes - catch fire. Many tales have been told of fires or nearly fires with shorting batteries. Only stock the batteries you need and ensure they are safely stowed and protected from shorts. When fitting or replacing new batteries take the plastic covers from the new battery terminals, label and date the battery and fit it. When you replace the battery, do not throw the old one in the bin. Instead fit the plastic covers from the new battery on to the old one, tape them in place and return it to your local recycling facility. Make sure when transporting batteries that they cannot be shorted out by other batteries, stray tools or metal parts.