UPS Making a Clicking Sound

How to: UPS appears to be malfunctioning - constantly turning on and off; clicking.

Two years ago, in this Keyliner article, UPS Battery Replacement, I replaced the lead-acid battery in my APC cs350 battery backup, fixing a problem where the laser printer fired-up, causing my workstation to reboot.

This week, a new problem arose when I could hear the UPS clicking on and off, every minute or so.  The UPS thought there was a brown-out, and was busy back-filling power.

Blame the Battery First*:

Naturally, my first inclination is to blame the UPS -- knowing a 2-year-old battery had likely failed.  Annoyed at the prospect, I promptly spent $40 on a replacement.   

The new battery was installed, and to my surprise, and later, chagrin, the problem remained.  Then, out of the corner of my eye, I saw the laser printer had a red-flashing error. 

Rebooting the printer fixed both the printer's problem and the UPS. 

For what-ever reason, the printer was in a bad mood and while quietly sitting in the corner, it was busy heating its fuser roller for a few days, drawing a ton of power.

*I wasted money on the new battery.


Lesson learned:
When a UPS is unexpectedly tripping, the problem is almost always upstream.  It could be a power-company brownout, but this is unlikely, especially if you see the problem for several days.

When UPS's misbehave, turn off other devices on the same (household) circuit before jumping to conclusions.  Turn on each device to confirm.

Consider the furnace or air conditioner, but if there is a laser printer lurking in the house, it should be the first suspect.  Laser printers are hogs.  Even though not plugged into the UPS, it draws enough power to affect the entire circuit.

Keywords:
Trip Tripping, cycling power-on, power-off

Related article:
UPS Battery Replacement