First off, I have a 2010 GMC Acadia SLT. Well I was driving the other day. It started up fine, and was running fine. I got about 4 miles from the house and a message comes across the dash saying service charging system. I could see the battery volts dropping down. Then it went into battery saver mode, and started shutting off the a/c fan, and radio. So I thought I better get this home. I took it home. Not knowing whether it was the battery, or alternator. So I pull up the panel in the floor, and take a voltmeter, and the battery is at 10 volts. So I get my battery charger and hook it up, and set it on trickle charge, and run the cords through the window, and use my other car to run my errands. A few hours later I come home, and it shows the battery is charged. It was showing 12.35 volts on my voltmeter. I decided to start the car and see if the alternator was charging it. I put the voltmeter on it, and it was jumping around. It would go up to 14.2, and down to 12, and just bounce around. I just took it the alternator was bad. So I shut it off, and went in, and found a alternator for good price on the internet. So I ordered it. This happened on Monday July 1st. So my alternator is suppose to be here tomorrow. So this evening I went out, and was gonna start taking the old one off. I go to get in the acadia and the doors wont unlock. I use the key, and there was no power. I put key in the ignition and muscle the wheels to the right to try to get the inner fender off with the wheel on, and the key wont come out now. I turned wheels back every which way, and the key is stuck in there. I go check the voltage on the battery and it is 2 volts. Nothing was left on in the car. So I put the battery charger back on it, and it has been charging for 5-6 hours on the fast 10 amp charge and it went up to 6 volts in about an hour and has stayed right at 6 volts since, and isnt changing.....What could have cause the battery to go dead in 6 days with no driving it, and nothing on. Could the problem have possibly been the battery all along and not the alternator? I flipped the charger to trickle charge, and I am going to let it go all night and see if it happens to charge up. If anyone has any ideas what I should do let me know. Thanks for any help.