What was found
ON 12/29/2023 AT 2025 HOURS, I WAS ATTEMPTING AN ENGINE START AFTER DROPPING OFF A PATIENT AT THE UNIVERSITY OF COLORADO HOSPITAL IN DENVER, CO. AFTER INITIAL STARTER WIND-UP AND INTRODUCTION OF FUEL, I COULD HEAR THAT THE START WAS SLOWER THAN NORMAL. AS I MONITORED ENGINE TEMP, I NOTICED A RANGE BETWEEN 860 AND 880 CELSIUS. THE TEMP WASN'T FALLING AND I WAS NEARING MY LIMITATION OF BEING ABOVE 843 DEGREES CELSIUS FOR MORE THAN TEN SECONDS DURING A START SO I ELECTED TO ROLL OFF THE THROTTLE AND ABORT THE START. SIMULTANEOUSLY, WE COULD SMELL A STRONG, SULFUR TYPE ODOR COMING INTO THE COCKPIT AND CABIN. AFTER SHUTDOWN, BATTERY VOLTAGE WAS INDICATING 21.5 WHICH IS BELOW THE ALLOWABLE STARTING REQUIREMENTS. I MADE THE NECESSARY NOTIFICATIONS AND A NEW BATTERY WAS INSTALLED ON 12/30/2023 AT 0845 HOURS. THE AIRCRAFT WAS THOROUGHLY INSPECTED FOR ADDITIONAL DEFECTS AND NONE WERE FOUND.