The UPS battery system is a stopgap between your main power source and your backup power. The problem is that even with a robust battery backup or generator in place, it can take several minutes for your system to respond to the loss of your main power source and begin drawing from your alternate source. In hospitals, banks, and other critical functions, these precious few minutes could be a matter of life and death. The UPS is designed to solve this problem by responding instantly, providing a big boost of power to the system, and then handing things off to your backup system as soon as it is up and running.