Q: Why does my APC Back-UPS® unit make different beeping sounds?

A: APC’s UPS units have audible alarms to provide users with proactive warning of changing UPS and power conditions. An occasional single beep from the UPS indicates that the UPS is operating normally and is protecting the load. When the Back-UPS unit is operating on battery power, you may hear the following alarms:


1. Four beeps every 30 seconds (and the amber “On Battery” LED illuminates). The UPS has transferred to “On Battery” because the input voltage has been determined to be unsafe for your connected equipment. Occasional transfers to “On Battery” are normal, and the UPS is providing clean, safe, and reliable power. The alarm will go off once the UPS returns to “On Line” operation. If your UPS has APC’s PowerChute® management software, it may be possible to change the default acceptable voltages.


2. A single beep, once or twice, is an incomplete “On Battery” indication. This will occur if the power disturbance is brief and should be considered normal operation. However, constant beeping (and flashing amber “On Battery” LED) indicates that the UPS has reached a “Low Battery” condition and is nearly out of battery power. If you have correctly configured PowerChute management software, it will automatically perform a graceful shutdown of your connected equipment. If you do not have the PowerChute software, you will need to perform a controlled shutdown of your equipment when you hear this signal.


3. Rapid chirping for one minute, every 5 hours (and red “Replace Battery” LED is on). The UPS has recently performed a self-test of the internal battery and the test has failed. The UPS battery should be replaced within two weeks of this notification to prevent the UPS from unexpectedly dropping the connected load.


4. One beep every 5 seconds. The UPS is in “Low Voltage Sleep Mode” following a shutdown of the UPS. The UPS is attempting to charge the internal battery with what little power is present at the wall outlet.


A complete list of audible tones for your particular unit is available in your Back-UPS user manual.


Check out our full range of UPS units at www.apc.com/products under the “UPS” section. Also be sure to check out our PowerChute products under the “Management” section.

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