Depends on the type of LiFePo4 cells, ones designed for higher power can easily do 5-10C or more. But that's not needed for a UPS. Most common high energy cells

Depends on the type of LiFePo4 cells, ones designed for higher power can easily do 5-10C or more. But that's not needed for a UPS. Most common high energy cells can handle 3C. 3C or 20 minutes of runtime would be in the realm of most UPS ratings (remember the LiFePo4 cells have a lot more energy/runtime in the same space).