BMW Repair: Car wont stay charged., 1985 bmw 318i, bmw 318i

Question
I have a 1985 BMW 318i. At first, the car ran well then all of the sudden the car quit charging. I took the alternator to the shop and had it checked. It was bad so I replaced it. The shop checked the new one and it was fine. The problem that I have is that, when you take off the ground cable, the car turns off. With the car on, checking with the voltmeter, the volts read 13.09 dropping .01 volts every minute. Checking the alternator directly (voltmeter) it reads the same as checking from the battery. I've replaced the ground and hot wires. There are two blue wires coming from the alternator(next to hot wire). Where do they go and what do they do. I think they might be the answer to my headache. I'm stuck, please help.  

Answer
Robert,
 Have you checked the battery to make sure its not the problem.  The alternator should be charging over 13v when idling, and probably aroubd 14v when actually running down the street.

 If the battery is bad, it will affect the alternator, because it's part of the loop.  Change the battery with another vehicle just for testing, and see what your measurments say then.
 I have a feeling the alternator is still at fault, but I could be wrong.

 Good luck,
 Josh