LS4 Performance - Problem with 06 GXP

Driving my car recently and every so often a message comes up on the display screen saying battery saver mode is active. this happens mostly while the car is in gear. the user guide says its to protect the battery when the car is in acc. so it seems strange to me to coming on while I`m driving. Any help would be appreciated

Test the voltage on the battery, may be getting close to time to change it. Or maybe the alternator, but I don't know much about that...