I received an APC Back-UPS 700 for free, but the previous owner removed the internal battery. It now beeps constantly whenever the unit is switched on. I mainly need extra outlets and surge protection because my apartment has very few conveniently placed outlets, so I was wondering whether the piezoelectric buzzer can be safely disconnected or removed. I'm not very experienced with electronics and would appreciate advice on the safest option.
4 Answers
If you only need additional outlets and surge protection, skip the UPS and buy a properly rated surge-protected power strip or outlet extender. It will be cheaper and simpler than repairing a battery-less backup unit.
I wouldn’t recommend removing or disabling the buzzer if you’re not familiar with mains-powered equipment. The alarm is warning that the UPS has no usable battery, and opening the case can expose you to stored electrical energy even when it’s unplugged. A replacement battery is much safer than modifying the alarm circuit.
The simplest and safest fix is to install the correct replacement battery. These units generally use a 12-volt sealed lead-acid battery, often around 7–9 Ah, but verify the exact specification for your model. Match the red and black connectors correctly, and label the battery with its installation date. Once the battery is installed, the alarm should stop and the UPS will work as intended.
Before assuming the buzzer itself needs to be removed, check whether the sound is coming through a small opening in the case. Covering that opening might reduce the volume for a quick test, but it isn’t a real solution and shouldn’t replace installing the proper battery.

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