UPS Backup, The Definitive Thread to UPS!!!

[yeldarbj]

The problem with most UPS systems is that they don't tell you what size the battery is. Most of the lower priced ones have very small batteries and are designed to take a heavy load for just a few minutes, just enough time to finish what you are doing and shut down your pc.

Here is a calculator that seems to work very good for calculating run time when you know the battery size.

http://www.xantrex.com/support/howlong.asp

[RobWein83]

thanks for all the help!! I finally got things worked out

[BeanAnimal]

Originally posted by FranktheTankTx
This was interesting...

I found a tool on APC that told me run time for specific power draw. The lowest option was 50w... which 2 K3's would only be 20w total.

Anyways, the run time is really weird to figure out. It's hard to assume what it would be if I cut it from 50w to 20w. But I feel safe that the 390w version would give me 2 - 3 hours of run time during a power outage.

If I were to increase this to a 500w+ back up... I might get 4 hours. But again, it's difficult to tell when I don't understand the math.

The VA rating of the UPS has nothing to do with the run time of the UPS, it dictates the maximum current that the UPS can provide to attached loads. The runtime is simply a factor the the battery size times the efficiency of the inverter.

A 1000VA ups with a 75Ah battery will give you the same run time on a 100W load as a 200VA UPS with a 75Ah battery... in reality the bigger UPS will likely NOT last as long because the big heavy transformer and output transistors are not likely as efficient as the one in the smaller UPS.

Bean

[jezzeaepi]

This is what I use. Note that it does not have a true sin wave, however its run my tunze 6025 and seio620's with no problem in the past. It has a 40Ahr battery which is a lot more then youll find in most models:
http://www.amazon.com/Xantrex-Techno...8399449&sr=8-3