On 12/11/13 09:31, Mark Rogers wrote:
On 11 November 2013 20:30, steve-ALUG@hst.me.uk wrote:
The lower the load, the longer the battery life. The higher the VA rating, the longer the battery life.
At least as I understand it, VA doesn't give any indication of battery life, and it's quite common to find cheap UPS's differentiating themselves on VA rating (1500VA is better than 1200VA, right?).
750 VA means it can deliver 250V at 3A. If your hardware needs 4A the UPS will fail to provide it and presumably go overcurrent and shut down. Whether it can provide 250V at 3A for 5 seconds or 5 hours is immaterial. So, for the same load, a 750VA UPS and a 1500VA UPS will last just as long (assuming all else is equal), but if you have a 4A load the former will fail to work at all where the latter will.
Really????
IMO, provided that you're not trying to draw more current than the UPS can provide, a bigger VA rating means a longer battery life.
This is broadly supported by this page on the APC website http://www.apc.com/products/family/index.cfm?id=165&tab=models
where the bigger VA numbers correspond with a longer run time. Also, a lower load power rating results in a longer run time.
I'd suggest going to the website http://www.apc.com/site/apc/index.cfm
Clicking on the products tab, then click on the relevant Sector e.g. (probably) Home/Home office then click on "Uninterruptible Power Supply (UPS)" and see what's available and get an estimate of capabilities. Also remember the APCUPSD website for models to avoid.
HTH Steve