I replaced my Monster Cable HT UPS 1000 which worked perfectly until the non-user replaceable battery died.Brand new, out of the box, I charged the J10-BLK for 24 hrs. Battery 100%.Unit repeatedly shut off when it self-tested battery or operated on battery function alone.Load consisted of LCD TV,Receiver, satellite DVR. APC customer service unable to help. How can a unit rated for 800 watts be unable to handle only 135 ? Thank you, Amazon, for making it easy to return your stuff.