We considered capacity and additional features like sinewave output, USB charge points, and surge protection when selecting the best UPS units, We only picked UPS units from reliable, well-reviewed brands that offer a premium product at a fair price. We also looked at UPS units of. When buying a UPS unit, look for one with enough outlets for all the devices you want to connect and the capacity to power at least the most important ones for several minutes if the power. Anything you plug into the wall with a plug runs on alternating current or AC. For a battery to power a device designed for alternating current, it must provide power in a sine wave. A pure sine wave, which has a much cleaner output, is suitable for sensitive electronics.