Because in-home sensor systems and User Experience are interests of mine, I offer this How To after replacing a sensor in my home alarm system.

We use an ADT home alarm system, and we’re happy with it. I know other sensor systems are just as messy to deal with, and hope this narrative can help all developers iron out the wrinkled parts of their users’ experiences.

1. The system starts chiming every so often in the middle of the night. User experience: HOW TO MAKE IT STOP SO I CAN SLEEP?
2. To stop the chiming,
   1. go to the control panel
   2. note the sensor number the system is complaining about
   3. enter the access code, press the button labeled Bypass, and enter the offending sensor number.
3. Go back to sleep. Forget all about the battery.
4. The next time you try to arm the system, it will fail to arm because the sensor is bypassed. HOW TO MAKE IT WORK?
5. Ignore it and leave the house unprotected. User experience: bad feelings about security and forgetting to replace the battery.
6. Days later, remember that there’s a battery to replace.
7. Go to ADT’s Battery Page to find the right battery for the bad sensor. Search the sensor in vain for the model number of the sensor. Try to play the battery replacement video, but find that YouTube labels it as private and won’t display it.
8. Buy a new battery, at a place that sells unusual batteries.
9. Have ADT ignore alarms while you replace the battery:
   1. Call ADT’s toll-free number from your home phone line.
   2. Wait for the voice tree to ask if the address is correct. Say Yes.
   3. Wait for the voice tree to ask for a few words describing the problem. Don’t speak a narrative assuming this is for a service representative – it’s not. Instead, say “sensor failed”.
   4. Wait for the voice tree to transfer you to a service representative.
   5. When the service representative has answered, give your address (even though the automated system confirmed your address).
   6. When asked what the rep can do for you, say “I want to replace the battery on a sensor.”
   7. The rep will put an “ignore” flag on your system for the next 30 minutes.
   8. Thank the rep and hang up.
10. Find a small flat-head screwdriver, a step ladder, and the replacement battery you bought.
11. Replace the battery – what you thought was the real task
    1. Find the opening slot in the sensor
    2. insert and twist the screwdriver to pop the sensor off.
    3. the system will start beeping loudly. Ignore it. Even though you called to have the monitoring service ignore problems, your local device doesn’t.
    4. While the system is beeping loudly, carefully remove the old battery and replace it with the new battery.
    5. The system will continue to beep loudly. Ignore it.
    6. Replace the cover on the sensor. The system should stop beeping.
12. Tell the system that the battery has been replaced
    1. Go to the control panel.
    2. Enter the access code and press the button labeled Arm. This will remove the bypass you entered earlier. The control panel should now show a failure in the sensor you replaced the battery of. Ignore it for now.
    3. Enter the access code and press the button labeled Off. The control panel should now show “Disarmed Ready To Arm”.
13. Test whether the sensor is working
    1. Enter the access code and press the button labeled Chime.
    2. Open the door or window that the sensor is attached to. The control panel should chime.
    3. Enter the access code and press the button labeled Chime, because the chime is really annoying. This action will disable the chime.
14. Celebrate! You’ve accomplished a trivial task!

Or, you can call ADT and have them send a person out to replace the battery.

Guess which method most people use. The resultant Truck Roll is one of the major expenses of home sensor systems.

Featured Image: “Woman praying to the Virgin of Guadalupe as her husband rages” by José Guadalupe Posada. Courtesy of the New York Metropolitan Museum of Art.