1990 Anniversary edition Electrical drain

I have a 1990 Mustang Anniversary edition with a 5.0HO. I have a very low system voltage, which slowly drains the battery. Over the last 2 years, I have replaced 3 batteries. Luckily under warranty. But these have been Heavy duty batteries. I have been told that it was the alternator, but I have replaced it as well to no avail. (I also replaced the battery at the same time just to be sure) Anyway when I replaced it the system voltage was high for a little while, but over the next month I noticed that my running voltage was slowly dropping, indicating to me that slow battery draw. Revving the engine of course will get the voltage to go up some, but there is a problem some where and it is driving me crazy. Has anyone had this problem or know of things for me to check and how to check it. Any information is appreciated. TIA

Hmmm...so when ur car is off it gets drained too?? If it is "draining" while you are in neutral & or on, your battery isn't getting a recharge from ur alternator or a bad charge. This may be a bad wire or short.
Stupid Question....have you checked the Trunk light, dome lights, and cig lighter for elec. shorts??:evillol:

Another thing..does this car have aftermarket pullies??? Sometimes the "new" alternator pully will cause a loss of charging and thus drain the battery some or a lot...so I have heard.....?:smokin:

:eek7:

No aftermarket stuff on this car. Strictly stock. And yes. :) I have checked all the connections on the lights as best as I can. Now they could still be draining the battery, but the lights are not on if they are draining it.

This happened to me once on another car i had and i figured out it was a drain in the battery. I had no clue where it was coming from so i bought a test lamp and unhooked the negative part of the battery, while the car was off, hooked one part of the test lamp to the terminal and the other to the battery terminal. And the light was lit up so i pulled fuses until i narrowed it down to the radio and just replaced that and i have yet to buy another battery and alternator in 6 months. Before i was replacing them once a month LOL it Sucked. May want to try that. Before taking it somewhere.