How To Replace An Alarm Battery

Help!  My alarm system is beeping or is showing a low battery alert!!

Alarm batteries tend to be good for a few years but if the battery becomes fully drained and the alarm continues to try to run, even a good battery may end up needing replacement.  Or if the battery is just too old it eventually won’t hold a proper charge.  We want our alarms to continue to run for a while during a power failure so if the battery is failing the alarm systems is going to warn you about it.  Or you might get a call from your alarm company if your alarm is monitored.


If you have a monitored alarm you can ask them to send over a service technician.  Yes you’ll have to pay for his time, travel and a new battery.

Or if you want to save some money and don’t mind rolling up your sleeves you can probably do it yourself.

Alarm System Battery
Alarm System Battery

Most alarm systems have a ‘main panel which you’ll find in your basement or electrical room.  Inside you will see a rectangular shaped battery with two wires attached to it.  On the side you’ll see something like 4Ah or 5Ah or 7Ah or 8AH and probably 12V.   This tells us it’s a 12V battery, and the other number is the size in ‘Amp Hours’.   4 and 5 Ah batteries tend to be the same size, as do 7AH or 8AH batteries.

So pick your self up a new alarm battery (we ship across Canada).  If possible unplug the power source to the alarm, and then paying careful attention to which wire goes to the + and which goes to the – terminal on the battery, unplug the wires.  If one of the wires is red, that will be the + wire.

Put your new battery in, attach the + wire to the + terminal on the battery and the – wire to the – terminal on the battery, plug the power back in and you’re golden.

If the alarm was showing a trouble condition there’s a good chance you’ll have to clear it by arming and disarming the system.  If this doesn’t work it could take up to 24 hours for the new battery to be charged so leave it alone and then check on it the next night.

Note: This article is for educational purposes only.  Please contact a professional alarm installer if you are not 100% comfortable doing this yourself and do not consider this article to cover every alarm available as some are all-in one alarms with integrated batteries.