Back-UPS ES 700 strange alarm behaviour

[maxpower]

Device: Back UPS ES 700

connected device: just one router, nothing more. for testing purposes: a lamp

When I pull the plug for test purposes, the ES 700 makes a very annoying high pitched terribly loud sound. Calling it a "beep" would be understatement.

It stops when I disconnect the consumer. While the ES 700 beeps the LED on the device is very low.

When doing the same test without any consumer connected, just the ES 700 and now pull the main´s plug, this sound does not occur.

The ES 700 does not tell to replace the battery. Though, the battery is aging and need replaced, i  know.

I just wonder whether to get a new battery or better retire the whole UPS. I dont want to waste the money for a new battery.

Thanks

EDIT: according to some Yt people with similar symptoms, this may be due to defective MOSFETs.

I´ll see if I find someone to repair. Though being old, I´m reluctant to throw away such pricy piece of hardware....

[JonPro]

Hi @maxpower 

Thank you for reaching out to the SE Community, my name is Jon and I will assist you with this query.  Apologies for the late revert, though there is a possibility that the UPS had an internal failure, it would also help if you can provide the exact model of the UPS for us to confirm the state that the UPS is in.