Quick quesiton about alarm system battery

[geryuuu]

So I built a small simple alarm system, with a couple PUT's and NPN's and a Relay. The schematic recommends a 12v battery be used. But I was wondering if I could just use a simple AC-DC adapter instead of a rechargeable battery. I was trying to think as to why use a battery, Im guessing incase the power goes out , the battery can still power the alarm system. But please let me know what you all recommend

[Sebi]

Hi,
the alarm systems work always with uninterruptible power supply. The simple wall-wart adapters contains only a bridge rectifyer and a capacitor, so the output voltage depend from load and mains voltage.
The minimum requirement a stable supply with 13,8V output, and a small maintenance-free Pb-accu with parallel (puffer) mode.