The batteries in this UPS lasted less than a year. It was because those battery were "no name" batteries, or because they were connected in series directly to the AC after the transformer? Shouldn't they have a rectifier and condenser before that? It seems that in this way the battery is connected to AC 24/7
Thats a transformer, it's outputting dc power. My main concern is that the batteries are sitting on end like that. They're filled with water, so if there's an air gap at the end the battery is not going to work as well.
Transformers change voltage, but they don't change AC to DC; you need a rectifier to do that.
It looks like they put that on negative side of the batt.