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UPS Power Backup calculations?

09/15/2009 12:22 AM

No. of Batteries: 10; Each Battery Capacity: 20V, 12 amp hr; 230Volts supply.

How can i calculate how much time it takes to discharge completely at o/p load of 10%.

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Guru
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#1

Re: UPS Power Backup calculations?

09/15/2009 4:59 PM

A google search of "UPS battery discharge calculation" produced a number of links to suitable calculation webpages and the formulas behind it (depending on how accurate you want the answer).

For example

http://www.solidstatecontrolsinc.com/techhpapers/pdfs/selectionsizingups.pdf

http://www.gizmology.net/batteries.htm

etc.

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#2

Re: UPS Power Backup calculations?

09/19/2009 12:04 AM

You have given 10 batteries and each battery is 20V/12amp hr. Total voltage is 230V.

And I presume that you connect your batteries in series connection. But in series connection the total voltage is 10 x 20V = 200V.

If you need to calculate how much time it takes to discharge completely at o/p load of 10% we need to know your total load. So what is your total load?

Asking a question like this, it is impossible for anybody tell you, how to calculate the time taken to discharge completely at o/p load of 10%. 10% of what?.

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Commentator
India - Member - ADIL MOULA Engineering Fields - Instrumentation Engineering - Adil Moula

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#3

Re: UPS Power Backup calculations?

09/19/2009 6:15 PM

given that battery capacity 12amp/hr X 20 v =240watt /hr

10 batteries in parallel will give 2400 watts

10% of of the load is 240 watts so 2400/240 =10 hrs approximate to discharge completely

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Guru
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#4
In reply to #3

Re: UPS Power Backup calculations?

09/21/2009 10:29 AM

The original poster did not state the load on the batteries, therefore this calculation is not valid!

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#5
In reply to #4

Re: UPS Power Backup calculations?

09/22/2009 9:01 AM

well what I thought that the battery capacity includes the battery load .offcourse I agree that some energy is lost across the battery which is constant but the battery specification do includes this losses .

regards

Adil

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#6
In reply to #3

Re: UPS Power Backup calculations?

10/27/2009 10:19 AM

thanks

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