Volvo Repair: 1991 940 Turbo, aftermarket radio, different places

Question
Hey there, I have an odd issue with my 940 Turbo, I love this car, it's amazing but I have a strange issue with it and no one has been able to tell me what is wrong with it.  About every 3 months the battery dies, I have gone through 3 batteries in the year and a half that I have had it, when I take it to different places to check the battery, they tell me that the battery has had total discharge and it is the car, but when I take it to get scanned for problems, nothing comes up on the computers, I have tried 4 or 5 different places...Please help! Thanks :)

Answer
Josh, sounds like these places are morons if they cant figure that one out.  Obviously there is a draw on the system somewhere and thats where they need to start.  Does the car have an aftermarket radio or alarm system? I would have to do tests to figure it out but a good Volvo shop will be able to figure it out.  Roger