WHILE DRIVING THE VEHICLE A MESSAGE CAME UP ON THE CLUSTER "START/STOP SYSTEM DISABLED. SERVICE START/STOP SYSTEM". SHORTLY AFTER THERE WAS ANOTHER MESSAGE "LOW BATTERY MODE. SOME SYSTEMS FUNCTION REDUCED". I LOOKED AT THE SYSTEM HEALTH STATUS AND THE BATTERY VOLTAGE WAS AT 11.2 VOLTS. WHILE DRIVING THE VOLTAGE CONTINUED TO DROP. I CALLED THE DEALER AND THEY ASKED ME TO BRING THE VEHICLE IN TO CHECK DIAGNOSTICS. WHILE DRIVING TO THE DEALER THE VOLTAGE CONTINUED TO DROP AND THE RADIO TURNED OFF AND WOULD NOT TURN BACK ON. WHEN I ARRIVED AT THE DEALERSHIP THE VOLTAGE WAS AT ~10.1 VOLTS. WHEN I PULLED THE VEHICLE INTO THE DEALERSHIP SERVICE BAY THE SERVICE WRITER CAME OVER AND WE AGREED TO NOT SHUT OFF THE VEHICLE AS WE WEREN'T SURE WHETHER IT WOULD RESTART GIVEN THE BATTERY VOLTAGE. AS THE VEHICLE IDLED IN THE SERVICE BAY THE VOLTAGE CONTINUED TO DROP AND THE VOLTAGE WAS JUST OVER 9 VOLTS WHEN I GOT OUT OF THE VEHICLE. THE VEHICLE WAS RUNNING AND WAS IN PARK. PARKING BRAKE WAS NOT ENGAGED. A DEALERSHIP EMPLOYEE GOT INTO THE VEHICLE AND WAS GOING TO MOVE IT BUT THE SERVICE WRITER ASKED HIM TO LEAVE IT WHERE IT WAS UNTIL THEY DETERMINED WHICH TECHNICIAN IT WOULD BE ASSIGNED TO. THE DEALERSHIP EMPLOYEE TOLD ME THAT HE DID NOT MOVE THE VEHICLE AND DID NOT TAKE IT OUT OF PARK. I WENT INTO THE WAITING ROOM INSIDE THE DEALERSHIP AND A FEW MINUTES LATER THE SERVICE MANAGER CAME OUT TO TELL ME THAT THERE WAS AN ISSUE WITH MY VEHICLE AND THAT IT DROVE INTO