Why does the UPS make noises?

[Anonymous user]

I have a APC UPS and first of all it has a buzzing noise, and I'm wondering why this is? When my cellphone is running with it's battery it doesn't make a buzzing noise, so why do UPS's have to make a buzzing noise?

Also, as I'm typing this message, my UPS makes a louder vibrating noise like a vibrating cellphone does. It only happens when i do things like type, load IE etc. When i do nothing this sound goes away and only the buzzing noise remains. Why?

[Erasmus_apc · Accepted solution]

An APC UPS would only make a "buzzing" noise when it is on battery (which is much larger and of a different type than a cellphone battery) and using it's circuitry to convert DC power back into AC for your equipment, or the fan has been engaged (for those models that have fans).

Are you sure the vibrating is from the UPS and not your PC? The UPS should not be making any "additional" sounds based just on what your load/PC is doing. What model and serial # is your UPS? Are you using the APC PowerChute software on your PC?