APC Power-Saving Back-UPS Pro 900 noise

[triton_apc]

This was originally posted on APC forums on 11/2/2011

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Hi. I'm planning to adquire an APC Power-Saving Back-UPS Pro 900, 230V and I'd like to ask a question about it. In the product specs it list a noise level of 45 dBA, which is pretty high. Does the unit produce this noise all the time or only when running on battery power? Also, does this unit have a fan? If it does, is it running all the time at full speed or does it turn on/off and has its speed regulated?

Thanks in advance for your assistance!

[R2_apc]

This was originally posted on APC forums on 11/7/2011

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Hi triton, yes the unit will be at its loudest when it is discharging on battery typically (due to the fact that fan will be running and the inverter will be in use). However when the unit is online the fan is typically not running and since the unit it just passing power through it will be much quieter. Hope this helps.

[triton_apc · Accepted solution]

This was originally posted on APC forums on 11/18/2011

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Hi again.

I finally bought the Back-UPS Pro 900 and sadly had to sent it back for noise reasons. I've tried two units, both with the same result. This unit has no fan but produces a lot of noise. The units I tested had three different noise levels. The louder one was when the system was running on battery power, which is expected and not a problem as it will only happen when there is a power cut and for a short period of time. There is a different noise when the battery is being charged. It's not as loud as when the UPS runs on battery but it's annoying. Notice it takes a lot of time to charge the battery. It shouldn't be a problem with a new battery, but it could become an issue when the battery gets old and requieres periodic recharging or if your power supply has frequent cuts. It's not critical, but there are other UPS that don't make a notable noise when recharging the battery. The real problem was a third noise, the one that the UPS produced all the time. It's much quiet than the one that's produced when the battery is being charged, but it's noticeable if you have a quiet computer, as I do. This noise was produced even with nothing connected to the UPS.

My power supply is stable, so I assume the AVR function was not working (and producing the noise). The LCD panel on the UPS showed stable in voltage and frequency.

So, in my opinion, this UPS is not good for a quiet computer (regulated fans, semi fanless PSU, SSD, 5400rpm drives soft mounted, quiet case). If you have a noisy computer it may hide the UPS running noise.