Can someone help trouble shoot my problem? I have a 1975 Dart and I just recently took it to the shop and I paid them to install a whole new audio system (Radio, wiring, and stereos in the back) It took 2 days to do it. The first day they ran out of time and the radio i was going to buy they said was defective and to come back tomorrow and they would hook up another one. 2nd day i goto their shop and when I go to move my car around the car wouldn't start because the battery was dead. And keep in mind that i recently charged my battery a week before because a couple of time i left my head lights on, which is why I recharged the battery in the first place. And so they hooked everything up and on my way back home my car turned off b/c of the dead battery. I called my dad to jump my car and he looked at the alternator dial on the dashboard and he told me that the needle is either supposed to be center line or above center line Positive and if the needle is in the
negative side then the battery is being drained fast.What should I do? Get a new alternator, battery, or is it the wiring? Or could it just be that my car can't handle the new car system?

well, alternator is not charging, replace that and pray it doesn't need wiring work too

Well I took it back to the audio shop and they said it could be because my battery is too Old and also because it's a marine battery. Ps before I started driving it my self for college starting last semester we would barely drive it, so it mostly just sat in our driveway So I take it to AutoZone and they used the battery reader and said that the battery is at 49% and asked me to turn on the car and the reader said that my power distributor failed. So we bought a new one and then me and my dad went home and the alternator dial was still showing almost the same results. And I have also left the battery to charge at 10 and I'm going to be letting it charge all day.

(And now I'm going to leave my battery charging all day) also (I still left in the new power distributor hooked up in my car) so any more possible reasons why my battery might have lost it's juce?