Security & Fire Protection Systems/back up battery


I replaced my back up battery and tested my system. The outside bell worked fine. I checked the system today and the outside bell did not respond. I checked the battery and it was down to 7.5 volts. The system is not keeping the battery charged. What do you recommend?

Need some more information before I can answer.  Manufacturer and model number of the system you have would be a good start.  Do you have the manuals?  These usually include a diagram of the main circuit board.  Can you identify the power transformer?  It's usually a small beige or white plug-in unit.  You'll see a screw holding it in place on the lower plug of a standard socket.  Are you comfortable with using test equipment like a voltmeter?  Is there AC voltage at the AC terminals on the main board?  Could be anywhere between 12.5 and 18 VAC.  Is there power at the socket?  If so, and there's no output from the transformer, chances are the internal fuse is blown.  You can obtain a replacement transformer from Lowes or Home Depot.  Please ensure the outputs match what was originally supplied.  This is extremely important.  Some Ademco and FBI products need a 12 volt transformer.  Hooking up a 16 or 18 Volt unit will destroy your main board.  If you need technical assistance (want to actually talk to someone), please don't hesitate to call our North America Toll Free number at 1-888-340-3473.  Good luck!


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Frank Kurz


Questions relating to Burglar Alarm and Security Equipment, Fire Alarm and Extinguishment Systems, Access Control, CCTV Systems, Installation, Service, Testing, Verification


30 years installing, servicing, and testing security, access control, extinguishment, and fire alarm systems

Chair of ULC Working Groups for Fire Alarm Testing (CAN/ULC-S536) and Fire Alarm Verification (CAN/ULC-S537), Executive Director of the Fire Protection Technicians Network (

Publications, Better Business Bureau Magazine, Applied Science Technologists and Technicians of British Columbia ( SUPPRESS! and Techs Fire Break Newsletters

Associate in Science; Emergency Systems (University of British Columbia); Aircraft Maintenance Technology (BCIT)

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