Thank you. I had a desi UPS and a normal car battery last summer and it was a bad experience. So, before buying a UPS/battery this year I did a lot of research.
I have heard some desi ups are good, so if you know of one that comes highly recommended and you are satisfied with its performance then you should go ahead and get it. The price seems expensive for a desi UPS. Does the desi 1500 watts UPS use one battery or two? Keep in mind if you go with either a homage or mercury 2000 W UPS you will need to buy two batteries with them. So, you need to see how much the whole system will cost you instead of just UPS.
Most desi ups produce square wave which is the worst. The imported Chinese UPS produce modified sine wave which is at least better than a square wave
Most desi ups exaggerate the amount of watts they can output. My last desi UPS was supposed to be a 1200 VA one but it could only support 2 fans and two energy savers. If you put third fan on it, there was a speed decrease on the first two fans. The homage 1000 VA that I am using right now can support 4 fans and 4 tube lights simultaneously. I have tested it with four fans and 2 tubes and two energy savers and it worked fine. Fans ran at full speed. So, this is something you need to take into account.
In Jan the homage 2000 W UPS was being sold for 9500. I do not know the price right now. but you should get a good deal as dealers must be worried that if they dont sell in the coming month then they will not be able to sell their ups till next year. So, bargain with them and get a good deal.
I do not run by laptop charger on my modified sine wave ups and although it will most likely work fine but as it is not designed to work with modified sine wave and square wave so it is not recommended to run it on such electricity. That is my recommendation.
Calculate the amount of total wattage you are going to put on the system and then use the calculator I gave earlier to get the right battery for your needs.
I hope I have answered all you question. Feel free to ask me if you still need help.
p.s. I recommend homage as so far it has not given me any problem and is running fine. Keep in mind that I only use ups for emergency use only. Meaning that even though it can run 4 fans but during evening time we all just gather in one room and have only 1 or 2 fans + 2 energy savers on it.