UPS reset power when trying to run Self Test

[cake756]

Hi there,

We have a APC Easy UPS SMV 3000VA 230V. Last week, we had a power cut. While a number of devices connected to the UPS were set up to shutdown gracefully via UPSMON, those devices simply lost power and all went offline at the same time. So today, I wanted to do a Self Test (by connecting to UPSCAPO via a USB cable.) The UPS simply had a power reset instead of running the test. So, all connected devices were either lost power abruptly or rebooted. 

The status says the battery is fully changer when I checked on UPSCAPO. 

Just wondering if anyone would know if that indicates a battery problem or perhaps something else please?

Thanks,

Edmond.

 

[Teken · Accepted solution]

The batteries are rated to provide 3-5 years of service life based on usage and environmental factors such as heat. If the batteries are more than five years old it’s time to replace them.

Based on your description of what happens upon a self test the cartridge are  bad and need to be replaced. You can validate this easily by removing AC Power.

If the unit turns off immediately this indicates the batteries are expired. If you take the battery cartridge apart and measure each cell you’ll probably find one or more cells are below 12.80 VDC. 

Keep in mind if you measure the voltage right when you remove the cartridge it will show above 12.80 VDC. Hence why you will need to let the battery sit and rest for 72 hours. If you come back and the voltage is below 12.50 - 12.70 VDC or below the cells are bad.

As a good cell won’t lose any voltage in just 72 hours. ☝️A more accurate test is to perform a load test based on the data sheet. This is followed by measuring the internal resistance of each cell and comparing it to the battery makers data sheet.

If the internal resistance is stated as 20 mOhms. And you measure double, triple the value or beyond the cell is toast from sulfication. 

Keep in mind you could also measure no resistance which indicates a dead short! A dead short would quickly drain any connected cells in the pack which reduces the overall service life of the cartridge.

Report back what you measure and observe. You’ll want to order a RBC which can be found on the LCD as to the model number if the unit is under warranty. If the unit is NOT under APC warranty you can simply rebuild the pack with high output CSB battery cells that come with the unit anyways! 👍

[cake756]

Thank you so much for the comprehensive instruction. I have planned an outage tomorrow so will be able to do some of the tests you have mentioned. Probably can't disconnect the battery for a prolonged period of time, but hopefully I can determine the root problem.

Cheers.