you should check with auto-electrical shops near your location on the condition of your car's alternator. Did you notice if the charge light went on while the engine or car was still running and lights started to dim? Worn out alternator carbon brushes could cause insufficient or no charging condition. They are quite cheap and easy to replace. The alternator has to be removed from the car to do this.
additional comment: power door locks erratic operation is due to low battery voltage being supplied to the system.