Canadian TV, Computing and Home Theatre Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter #1
I currently have an APC UPS as a backup for my VOIP home phone. The UPS's battery is a 7Ah 12volt. I have running off it a typical cable model (not sure of the watt draw), a typical wireless router (which draws about 5 watts), and a PAP2T phone adapter (which also draws about 5 watts).

Anyone have any idea how to figure out the run time off the UPS (perhaps assuming not a total battery drain so it doesn't kill the battery)?
 

·
Registered
Joined
·
2,818 Posts
Assuming a fully charged battery in perfect condition, your 7Ah @ 12v means 84 Wh capacity.

Now, that's the battery capacity. There's a bit of loss in converting from DC-AC, let's say 80%. That leaves you with 67Wh
If your modem draws 5W as well, you'd be looking at about 4 hours runtime (leaves a bit in reserve).
This is only a rough estimate, of course, and you shouldn't rely on it lasting that long.
If you want something for long blackouts to keep your voip phone up, I'd be investing in a high capacity UPS that could sustain it for several hours for sure.
Also keep in mind that even though you have battery backup for several hours on your end, it doesn't mean your cable system does..
(i.e. It's not much use having 24hrs of backup if the cable company only has 6)


edit: Looked at your link.
They provide a graph there.
~30W load is estimated at 100mins
assuming it's mostly linear in the extrapolation of that graph, roughly half the wattage should give you double the runtime, or 200 mins.
 
1 - 3 of 3 Posts
Top