here is what i did and here is what you should do... buy an apc ups(1500va) and a couple of dry batteries to go with them(atleast 100ah per battery)... then what you have to do is connect it and then what you have to do is that you should "forget about it for 5 damn years"... you will never notice a light going dim or a fan going slow... desi and other pakistani ups are shit... only buy apc ups(pure sinewave and used ones are as cheap as the local or chinese ones). Dry batteries are expensive but hassle free and super long lasting as they are deap cycle as well... never buy wet batteries...