I want to use sine wave inverter in UPS so that I can run my computer in case of power failure.

I'm not getting any of this. Why build one when you can get a used UPS for next to nothing? The big expense in the UPS is the battery pack. Fact is, the hospital I contract with rotates these things out the back door every year or two. There's nothing wrong with them other than tired batteries. The hospital decided long ago that the replacement cost of the batteries were so expensive that it made more sense to just buy new units. I'm a pack rat, so I was bringing these things home with me for years. My wife read me the riot act and they went out to the curb three months ago.... All 24 of them!

 

thank you guys for your support. I was wondering if I can charge my ups battery while it is supplying power to the load? Does automobile use the same principle that is they charge and discharge simultaneously? Also cell phones can be charged while we are using them so does it mean that we can charge a battery while it is delivering power to the load?

 

To be exact, the battery doesn´t charge and discharge simultaneously. The charger supplies the current for the load and then some more for the battery to charge.

Basicaly you have a diode and resistor (or a more complex charging circuit) from the charger input to the battery, another diode from battery to ouput, and third one from input to output, so that the load can be on even without a battery installed.

 

You should have a read through this explanation of the various types of uninterruptible power supplies:
http://www.pcguide.com/ref/power/ext/ups/types.htm

 

here is a schematic of an inverter. It uses a dual battery of +/- 24v. I would like to use this inverter in ups. I don't know how to charge dual batteries. Is it same as charging normal batteries?