What size battery backup (UPS)?

[Vortec]

I'm not sure if this is the correct place to post this in the forum but I figured since it is a form of a power supply it would be appropriate.

I am wondering what size battery backup would be efficient for my computer which has an Antec Earthwatts 500Watt 80% efficiency PSU. I've had it on an APC 350watt backup for quite sometime now but I also have an A/C unit in the same room (not plugged into the battery backup) and when I cut the unit on or the compressor kicks on I notice my battery backup will click and sometimes it will cause my computer to shut off. I'm guessing this is due to electrical noise but I was wondering if a bigger UPS would help this issue at all? I checked the price on a 500W APC backup and it was near $300 -- unfortunately I do not have that kind of cash to spend on one of those. Any comments/suggestions would be greatly appreciated. Thanks.


Also, my computer is basically the only thing plugged into the battery backup side of the UPS.

 

[ausch30]

http://www.apc.com/resource/include/techspec_index.cfm?base_sku=BX1500LCD
This is the one I have. I bought it from Circuit City on sale for around $180. I have 2 systems plugged into it and I like the fact that it has an LCD to show how much power I'm consuming and the large battery gives me around 20min of power if the power goes out.

 

[Vortec]

Thanks for the reply, ausch30. You got a very nice deal on that one it looks like. I'm not sure if I need one quite that large though but I did find this one. It's 540W rated and has ~5min run-time at full load which SHOULD be enough since I only need one to properly shutdown my computer or withstand the electrical noise I was speaking of.

 

[Guest]

The problem is not caused by noise. It is caused by the voltage drop caused by the compressor kicking in. The dip in voltage causes the UPS to sense that the utility power may go off therefore shutting down your computer. getting a bigger UPS may not solve the problem.