I do this to run my tv and computer during storms. its also a good way of isolating your electronics from power surges. just keep in mind that ups systems are not linear loads like light bulbs or heater elements. They have current draw patterns that small gernerators don't like to supply. We installed a large backup genset at a local gas company office and had to take several of their ups' offline to test the generator. The genset's manufacturer recommended that the maximum ups load be not more than 20% of the generator capacity.