A system for controlling power in a circuit breaker trip unit is disclosed. The system includes: a user interface operably coupled to the trip unit and having a plurality of input keys; a power conditioner operably coupled to the user interface and operably coupled to a battery power source and an external power source; and a power control circuit. The power control circuit is configured to automatically electrically connect the battery power source to the power conditioner in response to activation of any of the plurality of input keys, and in the absence of an electrical connection between the external power source and the power conditioner.