Originally Posted by dinasrt

You should be lasting much longer than 2 years of course, but a bad battery or alternator sometimes happens. Do you have a multimeter to check voltage? If not, most decent parts stores will charge and load test your battery for free. After you place the old fully charged battery in(or a new battery if necessary)they will also go out and test the voltage output of your alternator.
Also, you should check your serpentine belt tension and condition. Slippage@ the alternator pulley perhaps? That's all I got; good luck.