Need help on my charging system

I have a 92 vr4 and I am having problem with my charging system. I replaced my alternator because it shows on my reading on my digital volt meter my voltage is dropping while running. When I start the car after seating for a couple of days, the voltage reading is in normal, then it starts dropping while the car is idling after 3 minutes. So i replaced the alternator and also the battery and still the voltage dropping still there. So I went back where i got my alternator and asked them to replaced the alternator they gave because I thought it might be defective. They gave a another one and install it on my car and still have the same problem, now I assume it wasn't my alternator. This time I replaced the alternator relay and still have the problem. /ubbthreads/images/graemlins/banghead.gif I don't know what causing this voltage dropping, a help will be well approcciated.

list of parts i replaced:
alternator (twice)
battery
alternator relay.

thnx

 

[bazeng]

Have you checked the cabling to the alternator?

Confirm that you have a good connection to the battery from the alternator (confirm via millimetre / check resistance). Someone the wire can degrade overtime / break. Especially is you have oil leaks from the ps system our even from the engine. Check that it is grounding to the motor also.

 

thnx...i'll check the grounds to the alternator and engine

 

[FlyingEagle]

What voltage does the car start charging at and what voltage is it dropping to?

Check the FSM for voltages at specific temperatures here:
lilevo.com/mirage/