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
What is the make and model? Since it uses a full size transformer instead of switch mode supplies I'm going to guess its old and should be retired. Its old and inefficient, always consuming power to keep that large set of magnetics energized.
there's no make and model, just "1200VA UPS Made in China" and a what i suppose to be a fake CE logo