calculate battery runtime

Posted on 2004-10-21
Last Modified: 2011-08-18
Hello, I was wondering if anyone knew how to calculate max runtime for for an UPS.  I have the UPS table infront of me right now.  It shows something like
Load (VA)     Load (watts)     SU700     SU1000     SU1400
50               30                    142         224           269
100             60                     76          127           157
200             122                   37           64            80

How exactly would one determine the Load (VA), Load (watts)?

Thanks in advance,
Question by:joshuaemory
    LVL 69

    Expert Comment

    You posted the same question in Miscellaneous - you could have requested that it be moved here.

    The run time can be calculated by looking at MikProg's answer (the accepted answer) here:

    Author Comment

    hehe  Ya, I thought adding it in two places might double my chances of getting an easy to follow answer.  So what exactly would I be looking for on the power supply?  MikProg says "Take a sum of numbers signed on  every power supplay in your servers".  Is he taking a sum of the watts?
    LVL 69

    Expert Comment

    For time calculations, use VA (watts = VA x 0.7), so add up the watts and convert to VA.  Look at the ampere-hour capacity on the UPS.  Divide rated VA of UPS by output voltage to get total current output, then divide the ampere-hour capacity by total current output to get runtime in hours (multiply by 60 to get minutes).

    The important part is

    "The parameters you really need is UPS VA and battary AH. Serious manufacturers are always publish them. The only thing you need is check if UPS maximum allowed current is less then possible consumption it is
      UPSmac A > (400+500+450+...)/0.7/220 A"

    UPSmac should be UPSmax (maximum output current), and use 120 instead of 220 if the voltage is 120.

    Accepted Solution

      Posting duplicate questions in multiple areas is not the correct way to do this.  The total for a question may not exceed 500 points, and you cause confusion about which to post to.

    See this link for information regarding crossposting or creating pointers to  questions:

    points here (500) have been refunded.

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