[Al Skierkiewicz]

This from the RC reference guide 6/13/06
The Robot Controller cannot start running from Battery Backup power only. It requires Main Power connected at the required voltage to initially power on. If Main is lost and a link with an OI connected to an Arena Controller had been established, the RC will continue to operate with only Battery Backup power for approximately 4 minutes before it automatically turns itself off. If Main Power is lost under any other condition, the RC will continue to operate with only Battery Backup power for approximately 4 seconds or until the RESET button is pressed. This is to ensure maximum Backup Battery life.