UPS Ringing Sound
UPS Ringing Sound
Hello,
I wanted to check if this forum is suitable for discussing my situation. Recently, I swapped an old APC UPS for a CyberPower CP1500, but I’ve been experiencing an unusual problem. Sometimes I hear a very high-pitched ringing sound. It’s not like a typical electrical buzz or hum—it sounds almost like a tuning fork. The pitch is extremely high and just beyond what I can normally hear.
When I first connected the UPS, the noise came from the wall. After unplugging it and using a different outlet, the sound stopped instantly. Later, when I switched to another outlet, the APC was still plugged in, but the noise returned. Eventually, I removed the APC and connected the CP1500 to the same socket that had worked well for eight years. The issue persisted until yesterday.
Yesterday again, the noise came back very faintly. After unplugging it, it seemed to stop, though it was hard to confirm because of the buzzing when it switches to battery power. Once I plugged it back in, everything worked normally. However, this morning the noise returned once more; I unplugged and reinserted it, and it disappeared.
I’ve also noticed something else: when I’m not hearing the noise but the battery is full, I can pick up a very faint electrical buzz from the UPS—like a ticking sound that speeds up until it becomes a soft hum. This has led me to ask a few questions:
1) Is this a safety concern?
2) Could the noise be connected to the battery being fully charged?
3) If it’s not dangerous and the battery is full, is there a way to make the UPS discharge the battery periodically? That seems to help stop the noise temporarily.
Thank you in advance for any guidance!
It's probably coil whine as the ferrite cores used in high-frequency SMPS can ring at high frequency. I'd return it.
Most low-end consumer-grade UPSes are really terrible quality nowadays, with even APC often using an always-on fan that clogs with dust and then trips an error code when it stops spinning. That CyberPower model has a thermally-controlled fan but normally fails within 4 years because the glue they use to hold things on the board (to prevent things like coil whine) becomes electrically conductive over time and
burns up
or trips an error code. And the cheapest possible lead-acid batteries selected for these things won't last 2 years. I will say though that the APC warranty will overnight a new UPS to you, while CyberPower make you mail yours in first and give them a week to "inspect" it.
If your old APC is still ridiculously heavy after you've taken the batteries out of it, it may generate AC using a giant transformer sized for line voltages + frequencies much like many of the more reliable commercial grade UPSes still use, rather than those tiny ones that modern consumer-grade high-frequency inverter type UPSes use to save on copper. That alone would make it worth keeping and even upgrading the batteries on.
For the price of a new consumer-grade UPS you could get at least 50Ah worth of 12v LiFePO4 for the APC which would give you 10x the runtime and 5x the lifespan of new lead-acid batteries. If you'd rather the battery fit completely inside the UPS like the factory one, then give us the model number and we can look to see if there is a drop-in 7-12Ah LiFePO4 equivalent for it. Even a regular old starting battery that's no longer strong enough to reliably crank your car has way better performance than those tiny VRLA batteries that come with UPSes.
CyberPower is BAD? Bloody hell, I bought it based on reviews saying it was one of the better models. Is it likely to be dangerous? I don't think I can return it, it's a few months old. I didn't unbox it until about two weeks ago, but unless Amazon is feeling really generous it's outside any return period.
Since it isn't constant and seems to stop for quite a while if I unplug/replug the UPS, it makes me think it's related to the battery being fully charged. Is there a way to tell the thing to discharge the battery a little rather than keeping it fully topped up?
Is there a UPS brand you would suggest for when I can afford to replace this? I got the same brand for my father, too...
Thank you very much for your help!
Eaton/Tripp-Lite is likely the top choice for budget consumer models. CyberPower has consistently performed poorly, and it's notable that APC has also joined them in this regard. They still function reliably after four years and aren't particularly hazardous, so if your hearing isn't enough to notice, just replace it with a different model.
However, I wouldn't suggest these options anymore. High-quality industrial or commercial units have very low resale value, often ending up as scrap at prices similar to old scrap metal. Many companies shut down and dispose of their equipment, leaving buyers hesitant to purchase used items since repairs would be blamed on the faulty product. The key is that premium components rarely fail, and I own several affordable consumer-grade APC UPS units from the 1980s that are still operational today with LiFePO4 batteries. These have lasted about 40 years of continuous use instead of just four.
Yes, they do have limited capacity now, so they're mainly suitable for modems and routers today, but they keep running around the clock after 40 years and could last another 40. Interestingly, these older transformer-style UPS units are now prohibited from being sold new because they aren't energy-efficient, making them less environmentally friendly. To contribute positively, you can only purchase new ones shipped from China that have a lifespan of four years. How efficient must something be if it only works during power outages?
Thank you for the guidance. I'll need to consider my options carefully. At least it won't cause any issues...
Appreciate the support!