7.2V backup battery

From FIRSTwiki

The 7.2V backup battery, introduced during the 2003-2004 FIRST season, is a 7.2V rechargeable NiCad battery that is plugged directly into the robot controller. One has been supplied in the Kit of Parts since its introduction, but teams may supplement this with more of the same or similar battery pack.

Purpose

The backup battery provides backup power in case the main 12V battery is incapable for whatever reason (e.g., power spikes, low charge). The backup battery is also used to power any servos or the CMUcam2 used on the robot. This function is more likely to drain the backup battery than the backup function. Extensive use of servos after the introduction of the CMUcam2 led many teams to purchase higher-quality backup batteries than the one supplied in the kit and also led to the introduction of the backup battery charging circuit, which charges the backup battery by drawing power from the 12V battery.