Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great until it stops working

I've owned 2 of these now, but won't be buying any more. The battery only lasted a few months in the first one, making it useless as a UPS and just a very expensive way to plug several devices into one electrical outlet. The second one (another brand-new unit) didn't fare much better. Unless you are willing to buy a new unit every 6-12 months I'd avoid this one.The manufacturer wants more for a replacement battery than the whole unit cost, so that's not a good option.