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Back-UPS 550 constant screeching noise, solid green light

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.

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BillP
Administrator Administrator
Administrator
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589

Back-UPS 550 constant screeching noise, solid green light

This question was originally posted by DidYouTryTurningItOffAndOnAgain on APC forums on 11/28/2016


I am unable to find a reason for this status on my device: constant screeching noise and solid green light. 

I've tried resetting the device, removing and readding the battery. 

Any suggestions?


Accepted Solutions
UnexpectedBill_apc
Captain
Captain
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589

Re: Back-UPS 550 constant screeching noise, solid green light

This was originally posted on APC forums on 11/29/2016


I would check the battery's age. If it is more than three to five years old, it may be worn out and causing the unit to fail its "battery installed" or self tests. They will screech to high heaven if either happens. (Newer units with a multicolor power light will also show a red light. I'm not sure what older units with the single color light would do.)

A voltage test may not be enough to conclusively prove that your battery is bad. Even a truly "cooked" battery might show a healthy open-circuit (no load other than a voltmeter) voltage.

If the battery is OK, there is an internal fault. I've yet to see this or a similar model with an internal fault, so I'd just be taking a guess when I say that a welded relay contact may be to blame. Officially these things are considered non-repairable and no repair should be attempted unless you thoroughly understand the safety issues involved -- which are very real and serious!

See Answer In Context

1 Reply 1
UnexpectedBill_apc
Captain
Captain
0 Likes
0
590

Re: Back-UPS 550 constant screeching noise, solid green light

This was originally posted on APC forums on 11/29/2016


I would check the battery's age. If it is more than three to five years old, it may be worn out and causing the unit to fail its "battery installed" or self tests. They will screech to high heaven if either happens. (Newer units with a multicolor power light will also show a red light. I'm not sure what older units with the single color light would do.)

A voltage test may not be enough to conclusively prove that your battery is bad. Even a truly "cooked" battery might show a healthy open-circuit (no load other than a voltmeter) voltage.

If the battery is OK, there is an internal fault. I've yet to see this or a similar model with an internal fault, so I'd just be taking a guess when I say that a welded relay contact may be to blame. Officially these things are considered non-repairable and no repair should be attempted unless you thoroughly understand the safety issues involved -- which are very real and serious!