solo220 wroteGuys , are you talking about back-up UPS ( internal battery ) or the one with external batteries.
back-up UPS without load (only internal power loss) will not last more than 30 minutes max .
i think AvoK95 is not talking about back-up UPS.
Also FYI UPS systems which use external batteries are called APS (Automatic Power Supply)
There are two types of UPS systems as well , there's online and offline. The regular ones which you find at shops are offline, which means that when there is power coming from the wall the connected devices will use that power directly from the wall. They will only use the clean power given by the UPS when it's running on backup (No power on the wall)
An online UPS is a UPS that filters the power coming from the wall and always provide clean voltages. These type of UPS systems are a lot expensive than a regular offline UPS.
I am talking about regular PC backup UPS-s (Which are offline).
A UPS is not measured on how much it lasts. It depends on how many watts you use on that UPS. If you use a 650VA UPS and load a PC on it that draws 300W, it won't last 10 minutes , however if you use a modem which draws almost 30W it will last hours and hours.