I just installed a new battery in my car three days ago after it was losing power on the way home a month ago. The car steadily lost juice as it went further in my trip home and got really bad whenever I had to stop or slow down. Some of the electrical components of the car still worked when I got home (like the dome light), but otherwise it had lost all power. After I replaced the battery, it worked fine in town and on a 2 1/2 hour trip. When I came home the same night, it got about half way home before it did the same thing, gradually losing all of its power while I was on the interstate. The volt guage in the car steadily got lower. After a jump, the car went about six more miles before crapping out again complete with the lights dimming and brakes failing and steering wheel locking up.

My thinking is that the alternator has gone out, but I am not sure. Because the dome light continued to work, I am hesitant to say that it is definately the alternator. Is there something else in the electrical system that may have gone out? How much do these repairs cost?

Thanks,
Adam