Home Security Systems
Home Security System Repair Questions? Ask a Technician.
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Aside from the battery possibly being defective - measure its voltage while it is in-circuit to see if it genuinely is good enough, or just disconnect the AC power from the alarm system to see if it runs at all on just the battery (if that is easily possible - if not, don't bother with this test...) ...aside from the battery possibly being defective, you most likely need to log in with the administator code or master code, and go into memory and reset the 'battery error' or 'tamper error' flags. These flags may be persistent even after the error is relieved, in order to keep someone from bypassing the alarm system simply by unplugging it and removing its battery.
Measuring a rechargeable battery without any load (electrical power drawn from it at normal operating levels of the device) is not indicative at all, of its being failed/not-failed. A meter doesn't load it down.
What happens when you unplug the unit from AC power with the new, fully charged, batteries in it?