Core Issue
The I/O controller shares the system memory functions and the environmental monitoring functions for the Cisco 7200 series router with the network processing engine. The I/O controller contains NVRAM for storing the system configuration and environmental monitoring logs.
NVRAM uses lithium batteries to maintain its contents when disconnected from power. Some I/O controllers use a Static RAM (SRAM) component with an external lithium battery to provide the same functionality as the NVRAM.
Resolution
Replace the battery for SRAM.
For information on how to locate and replace the battery for SRAM, refer to Figure 2 in the Input/Output Controller Description section of Input/Output Controller Replacement Instructions.