HELP! battery/electrical problem

[EachIt]

My mustang has been having a real bad problem w/ the battery. Ill be driving along and all of a sudden my ABS and battery light will come on. The car will then start to sputter, and the revs will start to die off and bounce back up. About 30 seconds later (despite revving the engine) the car will die. I had it jumped, it started, the guage went to the normal range... and then I disconnected the cables and when I rev the engine it slowly drains the battery and dies again. I jump it, it starts again and dies.

I took it to walmart to buy a new battery (only place to buy a battery in this college town). They tested the battery and said it has 600+ cold cranking amps. They also said the alternatior was fine.

a little background: I have DVD/TV/amp in the car, but ive left it off the past week because of the cold. I figured the battery was straigned enough as is. The battery has been drained to failure twice.... but it was charged up on long trips...

soooo here are my thoughts.
1) its the battery and they are just dumb.. i need a new battery or a charger.

2) the alternator is messed up.

3) Theres something wrong with the computer?

thanks guys

 

[Sam98]

It is more likely that you have a short somewhere, and the wiring for the DVD/TV would be a really good place to start looking. It is also, equally plausible that the connection at the fuse block (behind the battery) has come loose, but that wouldn't explain the battery running down. I'm sure Walmart would love to sell you a battery, so chances are if they tell you it's good - it is.

 

[EachIt]

It is more likely that you have a short somewhere, and the wiring for the DVD/TV would be a really good place to start looking. It is also, equally plausible that the connection at the fuse block (behind the battery) has come loose, but that wouldn't explain the battery running down. I'm sure Walmart would love to sell you a battery, so chances are if they tell you it's good - it is.

Anything else it could be??? I had it all installed at Abt (anyone from Chicago knows what im talking about). I cant imagine them messing up such a simple install

 

[Sam98]

There are lots of things it could be. I would follow the positive battery cable all the way to the starter and make sure it isn't laying against the exhaust. You can rule out the DVD/TV by removing the fuse feeding it. Check the connection from the alternator to the fuse box. There is a nut that holds the positive battery cable and a terminal on. The terminal comes from the alternator and that is the first point that power enters to operate everything. The behavior you initially described sounds like the battery, but a loose (or corroded) connection at this point could easily give you that problem. It is also possible that you have a bad cell in the battery, while it worked in the store, it may not when the temperature drops below -50 like I remember it doing in Chicago. It is particularly important to have clean connections, especially when you are trying to drive heavy loads (A/C compressor, lights and rear window defroster) because if the connections are dirty, as you start running 60-100 amps through a bad connection it will drop most of the voltage you have available. The PCM and other critical systems will not function with voltages much lower than about 8V. If the terminals on your battery cables are corroded, it would be a good investment to replace both cables with a 4 Ga or larger cable. Good luck...