Power Systems & Backup Power for Alarm Systems Flashcards

A burglar alarm panel is installed in a location subject to extended power outages. The customer requests 72-hour backup. Which solution is most appropriate?

Answer: Add an external battery cabinet with appropriately sized SLA batteries wired to the panel's battery terminals

An external battery cabinet allows the use of larger SLA batteries beyond the panel's internal space limits, extending backup time while maintaining UL compliance with the existing panel.

What precaution must a technician take when replacing a sealed lead-acid battery in an operating alarm panel to avoid triggering a false alarm?

Answer: Place the panel in test mode or notify the central station before swapping the battery

Placing the panel in test mode or notifying the central station prevents a false dispatch when power momentarily fluctuates during the battery swap.

When measuring DC voltage output from an alarm panel's auxiliary power terminals, a technician reads 11.8 V instead of the expected 13.8 V. What is the most likely cause?

Answer: The panel's charging circuit has failed or the transformer voltage is too low

Low auxiliary output voltage typically indicates a failed charging circuit, an undersized transformer, or a faulty transformer — all of which reduce the regulated output below spec.

Which of the following is a correct practice when disposing of used sealed lead-acid alarm batteries?

Answer: Return them to a battery recycler or retailer that accepts lead-acid batteries

Lead-acid batteries contain hazardous materials and must be recycled through EPA-compliant programs — disposal in regular trash or landfills is illegal under federal and state regulations.

A central station receives repeated 'AC Power Loss' signals from a site during business hours. After investigation, the technician finds the alarm panel transformer is plugged into a switched outlet controlled by a wall switch. What is the correct remedy?

Answer: Relocate the transformer to a dedicated, unswitched outlet or hardwire it to an unswitched circuit

Alarm panel transformers must be connected to a dedicated, unswitched AC circuit to ensure continuous power; switched outlets cause repeated AC loss events and battery cycling.

What effect does temperature have on a sealed lead-acid battery's available capacity in an alarm system?

Answer: High temperatures increase capacity and low temperatures decrease available capacity

SLA batteries deliver more capacity in warm conditions and significantly less in cold — at 32°F, capacity can drop to 70–80% of rated, which must be factored into cold-environment installations.

An alarm system uses a 12 V, 7 Ah battery. After a complete AC power failure, the panel draws 600 mA in standby. How many hours of standby backup will this battery theoretically provide before dropping to the cut-off voltage?

Answer: About 11.7 hours

Dividing the 7 Ah rating by the 0.6 A draw gives 7 ÷ 0.6 ≈ 11.7 hours of theoretical standby runtime.