Computers & Electronics

How long should my UPS last before dead battery?

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  • Jul 24th, 2010 1:56 am
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Jun 13, 2008
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How long should my UPS last before dead battery?

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)?
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Plug it into a USB port and install Powerchute - it will show you load and estimated runtime.
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Kwirky wrote: Plug it into a USB port and install Powerchute - it will show you load and estimated runtime.
OK, thanks I'll try that. I was under the impression that just worked for the SmartUPS series and not the BackupUPS model that I have.
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flyboy320 wrote: 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)?
The UPS is designed for battery drain.

Just unplug your UPS and see. The beeping gets extremely frequent before the battery runs out. See if the time meets your requirements.

For battery maximum runtime, you need to replace your batteries every 3 years. After 5 years, you should definitely replace the battery or UPS unit.

You can order new replacement batteries for your APC unit.
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The reason I am asking is because the UPS I bought was a new one, but had been sitting around un-opened for five years. I figured the battery would be toast, but when I charged it up for 8 hours, and then unplugged the UPS from the mains, the battery powered the above equipment for two hours before shutting off. So I'm trying to decide if a new battery will give something like 24hrs before running out, or is 2hrs with the 15watt draw about right for a 7Ah battery.
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flyboy320 wrote: The reason I am asking is because the UPS I bought was a new one, but had been sitting around un-opened for five years. I figured the battery would be toast, but when I charged it up for 8 hours, and then unplugged the UPS from the mains, the battery powered the above equipment for two hours before shutting off. So I'm trying to decide if a new battery will give something like 24hrs before running out, or is 2hrs with the 15watt draw about right for a 7Ah battery.
What is the rating on the UPS - 325, 500, 700, 1500 VA?

UPS are ment to protect the equipment and data, so that they can be shutdown in an orderly fashion when the power goes out. (Or for emergency power to kick in.)

Emergency power generators are ment to keep circuits powered when the power goes out. (ie. Diesel generator in the garage.)

Even your router is on for 24 hours in a city wide blackout, your computers are unlikely to be operational, unless you have an emergency generator and lots of diesel fuel.

Not sure how long an uncharged battery be stored for. They ship UPS with the terminals disconnected. But sounds like you have a useable UPS.
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Busybuyer888 wrote: What is the rating on the UPS - 325, 500, 700, 1500 VA?
It's a 500VA...Don't need the router for internet browsing, just to keep the voip phone running...
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flyboy320 wrote: It's a 500VA...Don't need the router for internet browsing, just to keep the voip phone running...
The 2 hours is about maximum for your equipment.

My 3 year old Smart-ups 1500 kept my PC with 2 LCD monitors (24", 27") running for 20 minuites before it wanted to die. (recent test)
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flyboy320 wrote: It's a 500VA...Don't need the router for internet browsing, just to keep the voip phone running...
Bell deserved its fees for this feature, during the blackout many years back, the Bell land lines kept working.

It sounds like a VOIP home phone wouldn't last 12hrs even with a 1500 VA UPS.
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flyboy320 wrote: The reason I am asking is because the UPS I bought was a new one, but had been sitting around un-opened for five years. I figured the battery would be toast, but when I charged it up for 8 hours, and then unplugged the UPS from the mains, the battery powered the above equipment for two hours before shutting off. So I'm trying to decide if a new battery will give something like 24hrs before running out, or is 2hrs with the 15watt draw about right for a 7Ah battery.
Well, considering a 12V, 7Ah battery should supply 84 watts of power before giving up, in an ideal world you'd be looking at about 5.5 hours for a 15W load. However, battery capacities are measured over a span of 20 hours, and the efficiency of the UPS' inverter decreases as the load decreases; overall I'd guesstimate about 3-4 hours with a fresh battery, suggesting your load is actually 15W.

You're not going to get anywhere close to 24h unless you rig a car battery to it :razz:

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