Trying to get some opinions on this
So I got a cd player installed in my 318ti on Friday and right after I pulled onto the street out of the shop my car turned off at the light. It started back up and I drove home and it turned off once more and had been fine since. Monday I went back to the shop and told them about the problem and they said I need a new battery. I believed them and decided to get some speakers and figured id get a new battery later. After I left the shop my car did the same thing as Friday. I had been there forever getting the speakers done so I may go back tomorrow. I also noticed that the car starts rumbling like it's going to turn off when the volume is past 30. Is this a battery problem or did they do something wrong?