I've been a fan of APC for a while, but then the little 800VA unit I had decided to have a rather severe failure and not really do anything about it. Heck, the "change battery" light didn't even come on. So the batteries are connected in series, and one of the batteries failed.... Well, that little UPS decided that it just needed to charge harder.... I went into the guest room/office and smelled something electrical, and hot.... Couldn't find the source for a while, until my hand touched the case of the UPS.... Hot enough to almost burn my hand. Well, yanked the plug, let the thing cool off, and opened it up. Not sure exactly what failed first, but one of the two batteries was so overheated it had leaked the gel electrolyte through the connector. Won't trust a UPS that just keeps cranking amps at a failed battery to the point of nearly starting a fire.