I have a low power NAS (~35W) and I want to buy an UPS (uninterruptible power supply) to keep things running. The problem is most UPS for well known brands have an idle power usage (even without load) greater than 20W. It’s comprable with the NAS + HDDs + Network equipment…

Do you know any alternative? UPS battery for 10 minutes will be enough. UPS load could be very low < 50 W. UPS software is optional.