Home Security Alarm Tech Tips
Applicable To All Makes / Models:
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Alarm System Standby Battery Condition
The importance of the condition of the standby battery cannot be overstated. A good battery will ensure a longer period of operation for your home alarm system during power outages and may actually help protect the alarm circuitry from power surges and transients on the AC supply.
The latter is particularly true of older systems that can suffer corruption of programming by power surges and high levels of electrical line noise when the standby battery is weak and failing.
Most manufacturers recommend battery replacement every 3 to 5 years or at any time the system indicates a weak battery condition.
You can avoid premature failure caused by "deep-discharging" if you know what your calculated standby time (operation on battery alone) is and you turn the system off or disconnect the battery before exceeding that time during prolonged power outages.
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Testing The Standby Battery
Battery condition cannot be checked by simply measuring the open-circuit (no load) voltage across the terminals. The best method for testing a battery is to employ a battery tester that will check internal conductivity and provide an indication of battery condition and life expectancy.
In the absence of a battery tester, assuming that the battery has been receiving the proper trickle charge from the control, a rough idea of battery condition can be determined by measuring the voltage across the battery terminals while it is connected to the control panel and then measuring the voltage again after unplugging the low voltage transformer.
Most systems will float-charge the battery at approximately 13.5 - 14 V.D.C. and a measurement across the terminals 13 - 14 V.D.C. is acceptable.
If the voltage across the terminals drops below 11.5 V.D.C. when the low voltage transformer is unplugged, the battery is suspect and should probably be replaced.
