This is the most confusing thing to research. I want to eliminate the battery backup on the ONT (I understand what I'm doing on that front) and connect a UPS unit instead. I cannot get a clear idea as to what size UPS I'd need to run for a few hours in the event of an outage. I want to connect ONT, Quantum router and a 4 port switch all are co-located. I have a POTS line as well. That's it. Thank you!
I made a video that is in the How-To videos in the right column. That talks about how to remove the battery and substitute in at UPS, but it sounds like you as past needed that. In that video, I mentioned that I used an APC BackUPS-750. That USP is powering only my ONT and an ECB6200. I'm not sure how long it lasts. I suspect it's on the order of an hour to two hours, but it's far longer than any the UPS hooked to any of my desktops, so anything over about 20 minutes is moot.
Calculating how big of a UPS you should need should be possible by adding up the power requirements of the individual items. I'm no UPS expert, but I've no doubt whatever I'm forgetting will be pointed out.
I looked at a Netgear 5-port gigabyte switch I have and it has a 12V x 0.5A max power draw or 6W.
The wild card would probably be the ONT since there are quite a few models out there. Mine is a Tellabs 1600-611. I looked up a fairly official looking manual for the 1600-611 and 1600-612. They both list a max power draw of 12V x 2.0A or 24W. Try finding the user manual for the ONT you have.
For the example above, I've got 36 + 6 + 24 = 66W. That is the max power draw, but for the purposes of calculating the worst case, that is a good starting point. Trying out the UPS configurator at APC, it seems to recommend a BR1500G. I'd probably go with the BX1500G, which is what I use for my gaming desktop. APC PowerChute reports that I'm using 147-155W and estimates my runtime at 36 minutes. At 66W, I would expect that to go to about 80 minutes. There are also UPS calculators at Xtreme Power Conversion and Eaton. I found others that were less useful or too "industrial."
[Be nice! We are mostly fellow Verizon customers. My setup: 75/75 Mbps; Linux router (2x 1Gbps ports) + iptables; Linksys WRT1900ACS in Bridge Mode]
Thanks so much for the reply! I'd be curious to know what others say on this as well. I'll definitely try and navigate to your video. I'm thinking 1500va to be safe. I wish I could get a couple hours run time. Maybe others can confirm that that indeed could be the case or not. Many thanks!