SMT1500RM2U is making a screech noise and shutting off devices connected to it

[Alan_7777]

Hello,

My SMT1500RM2U is making a screech noise and shutting off devices connected to it. It happens very seldomly, about every 1-6 months for the last year and a half. While the batteries are quite old, I have ran several tests and it appears the batteries support power to my desktop and flat panel monitor for about 10 minutes before power is normally disconnected. There wasn’t any unusual load I could imagine coming from my setup before the power was disconnected from the UPS to my desktop and monitor.

Questions:

- is this a known issue? Most of the information I can find usually describes constant noises and usually power disconnects between the UPS and the devices are not mentioned.
- while I am happy to replace the batteries in the unit, my fear is that they will not solve the issue.

Thank you.

[Teken]

The batteries are rated for 3-5 years based on usage, temperature, and environmental factors. If the batteries fall within this timeframe or longer it’s time to replace them.

Ideally you would conduct a combination of tests and measurements to validate the state of health of the cells / cartridge. That involves voltage, resistance, capacity, and operational runtime tests.

The system offers basic rudimentary testing and validation such as the 14 day Self Test. You may also manually initiate a battery calibration.

The Self Test generally speaking is a basic POST (Power On Self Test). It checks for internal faults and a crude battery voltage load test to determine a Pass / Fail.

If the batteries are more than five years old conducting a (Load Test) via the battery calibration will either result in a complete failure or drastically reduce the operational runtime of the cartridge.

As it relates to the noise you’ll need to make a video of the sound. Generally speaking noise comes from the internal fan. Whether it’s failing bearings or just plugged up.

Other sounds come from the inverter section of the unit. Those sounds can be a hum, buzz, to what may sound like slight hissing.

The primary cause is from the transformer. Sometimes the sound can come from the relays as they Arc.

All of the APC Enterprise class UPS have a dedicated (Relay Weld) active fault / error code which obviously tells you this is a root cause failure in their hardware! 🤦‍♂️🤢

If you take off the top cover it will be easier to identify the area of the noise. Any obvious signs of heat damage on the main board indicates it’s time to retire the unit.

If there is no obvious heat signs than wait until you hear the sound to narrow down the area / zone.

Let me know what you see and observe. 

NOTE: If the battery cartridge is really old you better open it up! ☝️ As often times a hissing / random noise is the battery venting. You’ll quickly see corrosion and the battery casing showing signs of swelling and deformation.

[Alan_7777]

Thank you!
I would be hard to capture the noise without a continuous camera pointing at the unit as it only happens seldomly.

The unit did it again yesterday. It was plugged into a wall receptacle with nothing plugged into the unit itself. It made the screech noise again like before and reset (based on the info on the display).

I'll continue to research based on your feedback. Thanks!

[Alan_7777]

first video is the unit being disconnected from power and the screech noise / reset occurs when it is plugged back in.

second video is the unit screech noise / reset occurring when power was disconnected.

these videos only demonstrate the noise and behavior of the unit and do not match the typical scenario of the unit making the noise and cutting power to an attached device out of nowhere.

based on these videos and the information previously posted, i am concerned replacing the batteries won't fix this issue.

[Teken]

Hi Alan,

Appreciate you taking the time to record the behaviour and sounds from the unit. Based on the two videos the battery cartridge is well past it’s service life.

I don’t know what the attached load is on the system but in the video you can see the battery percentage is dropping off very quickly.

You can easily validate this doing a (Lights Out) test by removing AC Mains from the wall outlet. 

The first test is a static test of the unit with (No) attached load. If you compare the operation runtime from APC you’ll get a rough idea of the amount of time a new cartridge would provide.

With no load the UPS would easily operate for 60 minutes plus. ☝️

A dynamic test is done with a defined known steady load. Attach anything  except your (Computer) from a fan, heater, monitor to the UPS outlets. If you compare the APC Runtime Calculator to a specific load (wattage) say 150 watts. Their table may indicate the above load (150 Watts) should provide you approximately 60 minutes of runtime.

If you see 5-10 minutes the battery needs to be replaced. If the unit shuts down immediately or offers only a few minutes the battery is toast! 

NOTE: The noise you hear are the relays and inverter trying to transfer over / make contact whether open / close.

But the battery capacity isn’t healthy enough to accomplish this task. ☹️

[Alan_7777]

Hi Teken,
Thank you very much for the feedback. I will post an update after the batteries have been replaced.