Most of your store bought UPS last a few minutes to an hour, mine that I made myself lasts 5 days at 24/7 usage, charges back up with a 375watt panel if there is sun in less than 5 hours and has a 10 year warranty on the battery that is a Life4po 120AH battery connected to a wall charger and a pure sine wave inverter so my equipment is running on even cleaner power than the grid. In a power loss I am already technically plugged into the battery, so when power returns the lithium charger starts back up or if it’s a few days without electricity my solar panel will do the work.

All for 900$

Compare what you get for 900$ from a store bought UPS, is maybe a few hours run time. But at least it fits into a rack right? Who cares if it’s rack mountable or not, I want power and durability not a plastic box with a shitty lead acid battery that will have a 1 year warranty on it.