The vehicle has a battery saver feature designed to protect the vehicle's battery.
When any interior lamp is left on and the ignition is turned off, the battery rundown protection system automatically turns the lamp off after 20 minutes.
This prevents draining of the battery.
Electric Power Management
Accessory Power Outlet(s)Chevrolet Cobalt Owners Manual. Instrument Panel
A. Outlet Adjustment.
B. Turn Signal/Multifunction Lever.
C. Cruise Control (If Equipped).
Driver Information Center (DIC).
D. Instrument Panel Cluster.
E. Audio Steering Wheel Controls
(If Equipped).
F. Hazard Warning Flashers.
G. Windshield Wipers and Windshield
Washer.
H. Audio System ...