Smart UPS 620 utility light on but computer restarts

[Anonymous user]

I have a Smart UPS 620 with my computer, monitor and Internet router hooked to it. The utility LED light is lit up.  The UPS will beep and everything restarts instead of it staying on with battery back up.  We have a lot of power surges and I have replaced the battery once already.  Please help me figure out why it won't keep my electronics on anymore.  It's annoying.

[Anonymous user · Accepted solution]

There are a few possibilities.

First thing I'd check is the replacement battery. If it is more than a few years old, it could be worn out. A battery from a third party, while they generally work fine, might be of poor quality or old stock. Genuine APC batteries have a serial number from which the week and year of manufacture may be determined. Third party batteries usually have a date code stamped into the battery case.

An easy way to test the UPS without any danger to your equipment would be to temporarily disconnect it from your computer and other equipment. Plug in a simple device like an incandescent lamp (at least 60-75 watts) to the UPS. Pull the plug on the UPS and see what it does. If it fails or runs only for a short period of time, you probably have a worn out battery.

Another possibility is that of some equipment being sensitive to the incoming AC power waveform. When your Smart-UPS 620 runs from its battery, it outputs what is called a "modified sine wave". This is basically a square wave with periodic steps to zero output. Certain computer power supplies are sensitive to this and they'll shut down or restart when the UPS switches to its battery.

With this being a Smart-UPS, there is a special calibration procedure that may have to be performed before the unit will accept that it has a new battery. If you just installed the new battery and you're sure it is both of fresh and good, I can tell you more about how to do this. It's not difficult. If the calibration is off and the power fails, the UPS might shut down suddenly, even though the battery itself is good.

You can also check the battery with a DC voltmeter, if you have one. If the UPS is charging the battery properly, it should be around 12.5-13.1 volts when disconnected from the UPS and tested.