Question:
The lead acid battery in my home alarm system is depleted and need replacement. I have a question and hopefully someone expert enough can answer this. Is there a good reason that I should not replace the battery with an equivalent wall powered ac/dc to power the alarm circuit? Is the battery there for the purpose of safety, security, or just convienience? If it all posible, I want to have a wall powered ac/dc (with equal or higher in current comsumtion) replace the battery so that I dont have to replace it every few years.

Answer: Well, there's a good logical reason not to do this... What happens when the power to the house is cut - For *ANY* reason, whether sinister, honest, deliberate, accidental, or otherwise? The "Why?" of the power loss is completely irrelevant. The only thing that counts is the "It's gone" part. How well do you think the alarm system is going to work in that situation once you've converted it to run off the power line, instead of the battery? Now think about how well the alarm works when the power goes out, but the alarm is powered by a battery that's kept on constant standby charge as long as there's power on the mains. World of difference, huh? In a nutshell, if you don't care that the alarm ceases to function if the power goes out for some reason, then sure - You can do exactly what you're talking about, with no problem whatsoever. If it's important to you that the alarm continue to function even if the power is cut, (For instance, if it has a fire alarm subsystem) then the ONLY way you're going to get that to happen is replacing the battery as specified.