I'm thinking battery. Start the car and take it for a long drive. Then turn the car off and disconnect the positive terminal from the battery and let the car sit over night. Without reconnecting the battery in the morning - check the voltage on the battery - if it is below 12 volts - you have a bad cell - if it is still below 11 volts - you have 2 bad cells. If it is about 12.56 volts or higher - then you have something draining the battery. Let us know
Morris