It's the end of an era.

[presta]

UPS is an uninteruptable power supply. Basically a battery back up that gives mains power all the time. I know we have had issues at work with a whole host of communication systems failing on power failure. Like others have said you used to be able to just plug an old corded phone in and off you go. Not so now.

There's a difference between a UPS and a backup power supply though. A UPS is for protecting against short term interruptions & brownouts to protect any systems that are sensitive to even brief loss of supply, a backup supply provides an alternative source of power for protracted periods, not necessarily without brief interruption.

 

[Regular.Cyclist]

I was looking at getting one of those to run my boiler when there was talk of power cuts a couple years ago, but most of the ones on Amazon last for minutes rather than hours and days.

UPS capacities are given in VA. For example a 120VA would last for 30 minutes if the load was drawing 1A or 1 hour if the load was drawing 0.5A.

I bought a 500VA one and my router typically draws 0.2A so I would have a run time of around 10 hours.

 

[presta]

UPS capacities are given in VA. For example a 120VA would last for 30 minutes if the load was drawing 1A or 1 hour if the load was drawing 0.5A.

I bought a 500VA one and my router typically draws 0.2A so I would have a run time of around 10 hours.

I don't think you understand the difference between energy and power. 120VA is a measure of apparent power, it tells you nothing about how much energy the battery stores, and without that you don't have the information required to calculate the run time.

Here's an example of a 550VA/330W UPS which quotes a run time of between 4 and 8 minutes supplying a computer of unspecified power. It's very conspicuous that virtually none of the UPSs on Amazon specify the battery capacity explicitly.

 

[Regular.Cyclist]

I don't think you understand the difference between energy and power. 120VA is a measure of apparent power, it tells you nothing about how much energy the battery stores, and without that you don't have the information required to calculate the run time.

Here's an example of a 550VA/330W UPS which quotes a run time of between 4 and 8 minutes supplying a computer of unspecified power. It's very conspicuous that virtually none of the UPSs on Amazon specify the battery capacity explicitly.

Sorry, I was travelling at the time and having a conversation around CCA in car batteries so mixed myself up with VA and Ah.