Question UPS Ringing Sound

[blatherscribe]

Greetings,

I hope this is the right forum to ask about this, my apologies if not. I recently replaced an ancient APC UPS with a CyberPower CP1500, and it's having a strange issue. I can sometimes detect a very high-pitched ringing sound. This isn't an electrical buzz or hum, it's like someone struck a tuning fork. Very high-pitched, right at the edge of what I can hear (for clarification, I have an unusual hearing range, and used to be able to hear dog whistles before I aged out of it).

The first time I plugged the UPS in, the sound was clearly coming from the wall. I unplugged it and it stopped immediately. I switched to a different outlet, where the APC was plugged in. I had both on the same outlet for a few days as I switched things over, but the sound returned. I removed the APC, moved the CP1500 plug to the socket that had been trouble-free for the past eight years, and all was well... until yesterday.

Yesterday I heard the noise again, but very faint. I unplugged the UPS and it seemed to stop, but it was hard to tell given the buzzing it makes when it goes to battery. Plugged it back in and everything was fine. But the noise was back this morning; again I unplugged it and plugged it back in and it went away.

I've also noticed that when I'm not hearing this noise but the battery is full, I can detect a very faint electrical noise from the UPS, sort of a ticking sound sped up until it becomes a faint buzz. So I have a couple of questions:

1) Is this dangerous?
2) Is this related to the battery being full?
3) If it's not dangerous and is the battery, is there any way to tell the UPS to discharge the battery periodically, because that seems to stop it for a while?

Thanks in advance for any advice!

 

[BFG-9000]

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.

 

[blatherscribe]

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!

 

[BFG-9000]

Eaton/Tripp-Lite is probably the best now for low-end consumer grade models. CyberPower has always been pretty bad and it's surprising that APC have decided to join them in being bad too. I mean they still do work for 4 years and aren't dangerous, so if your dad can't hear it anyway, just swap it with his.

But I don't recommend any of those, when the high-quality industrial/commercial models have almost no resale value so can be bought used for pretty much scrap metal prices, especially if they are heavy enough to require truck shipping on eBay. There are almost always companies going out of business + getting rid of equipment, and buyers for other companies won't touch used equipment because if it breaks they will get blamed. The secret is the good stuff almost never breaks, and I have many cheapo consumer-grade APC UPSes from the 1980s I originally bought for 386 PCs that are still working fine now with LiFePO4 batteries. So 40 years of continuous service, rather than 4 years.

Yes, they are pretty low-capacity so only run modems + routers and such nowadays, but they are still running 24/7 after 40 years, and will probably go another 40. The funny thing is over here these old transformer-style UPSes are now illegal to sell new because they aren't efficient enough, so therefore not eco-friendly and in order to save the world you can only buy new ones shipped from China that last 4 years. How efficient does something that only operates during a power outage need to be?

 

[blatherscribe]

Thanks for the advice. I'll have to see what I can do. At least it won't catch fire or anything...

Much appreciated!