battery drainage

There's definitely a draw on your battery eg interior light, brake switch causing brake lights to stay on , see how much amp is drawing on your battery first

Look for something mistakenly left on like your interior light switch or courtesy lamp switch. Also check that exterior lights like assist lamps on doors or mirrors go off after exiting the vehicle. If no cause can be found, then proceed like Terry said and determine the level of draw on your battery. Once you verify that there is a current draw, begin by pulling circuit fuses one at a time to determine what circuit is causing the problem. Then go after items on that circuit until you find the problem. Good hunting!