My 2008 Chrysler sebring keeps having a dead battery. I have already replaced the battery and I still have the problem.

Either the alternator is not charging or something is draining the battery.

tenspeed is right also make sure your ground wires have a good connection

Start the car. While the car is running, disconnect the positive battery cable from the battery. The car should still run. If the car dies when you do this, the alternator is probably bad.

If you disconnect the battery well the car is running, on a 2008 Sebring, you will be telling the computer that there is a break in the electrical circut, this will bring up a code on your dash. This will be more difficult to fix than just doing a load test on the battery in the first place. Get a load test on the battery, well the car is running to see if it is giving you 13 to 14 Volts, then you know your alternator is working

check the relay under the hood, make sure you do the right thing, don't do any unnecessary repair, it can be an easy fix. It may not be battery, starter or alternator check relay