How to Change a Backup Battery in an Ademco VISTA-20P Alarm System

The Ademco VISTA-20P alarm system uses a battery for backup power should the home's electric lines fail.

You can replace the battery yourself, should the one inside the Ademco control panel be drained of power. A replacement battery can be acquired from the same location as where the Ademco alarm system was purchased (for example, a security service center). Household tools will be needed, but no special skills are required. The alarm system will not be damaged in any way by changing the battery if it is done properly.

Enter the password into the keypad to disarm the Ademco VISTA-20P alarm system. Trip the circuit breaker supplying power to the 20P's control panel at the fuse box.

Remove the screws from around the control panel using a Phillips screwdriver. Pull the cover off the control panel and place it aside.

Twist the screw tabs at the top of the battery counterclockwise to loosen them -- the battery is in plain sight inside the control panel. Remove the lugs attached to the end of the red and black wires from around the screw tabs. Pull the battery out of the control panel.

Place the replacement battery in the control panel so it occupies the same position as the other battery did. Loosen the screw tabs on the top of the replacement battery.

Place the lug from the red wire around the leftmost screw tab on the battery. Place the lug from the black wire around the other screw tab. Tighten the screw tabs.

Place the cover back on the control panel and reattach the screws. Restore the electric power at the fuse box. Enter the password into the keypad to initialize the alarm system. Navigate to the "Reset" menu and activate this function to reset the alarm system.

Things You Will Need

  • Phillips screwdriver
  • Rechargeable battery, 12VDC, 4AH minimum


  • Warn the off-site monitoring service beforehand that you are disconnecting the alarm system.

About the Author

Marshal M. Rosenthal is a technology maven with more than 15 years of editorial experience. A graduate of Brooks Institute of Photography with a Bachelor of Arts in photographic arts, his editorial work has appeared both domestically as well as internationally in publications such as "Home Theater," "Electronic House," "eGear," "Computer and Video Games" and "Digitrends."