Many smart devices have built-in battery packs, with modern laptops packing enough cells to last a whole day. However, typical desktop computers, routers, and similar devices still need to be plugged into a power source all the time to work. That's where an uninterruptible power supply (UPS). Our pick for the best UPS overall goes to the APC BR1500G Backup Battery. At 1500VA/865W, it can power most devices, including computers, external hard drives, and wireless routers, from a few minutes to several hours, depending on the total connected load. This. If you need a UPS and don't want to spend a lot, the APC UPS BE425M Battery Backupis for you. Its 425VA/225W power won't keep your desktop computer running for several minutes. The Amazon Basics Standby UPSis great for those who want a UPS compact enough to fit in a small space but packs decent power for their equipment. It measures. Most laptops have a long enough battery life to last anywhere from a few hours to an entire day. So, if you don't have a larger, more power-hungry desktop, you only need a smaller.