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How do I replace the battery in a first alert FA120C system? The system beeps every 40 seconds.

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Hi Nzingha. Check your mail panel, it should show which zone has got a battery problem, if no zone is shown, it is the main backup battery that is low, this should charge all the time while mains is available so it will only happen if the standby battery has a problem.

When you have determined which sensor has a low battery, use a flat screw driver, look for the small slit/indent and lift the front side from the rear to open. You should be able to see the batteries then, replace with the same making sure about the polarity when reinserting the new ones. Some sensors also have a pushbutton that you have to press when all batteries are out to reset the sensor. Hope this helps, see attached manual.;s%20Manual.pdf

Posted on Nov 15, 2014


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