spoolinfc

ok, hopefully someone from this forum can lend me some advice on what might be going on with my car. about six or seven months ago my car decided it would start shorting out alternators at random and i cant figure out why. i have a aftermarket stereo in it and i previously had a amp and sub hooked up with it as well but i took that out when my last alternator kicked the bucket. so far ive been through about 6-7 alternators. ive taken the car to an electrician and they rewired my harness to the alternator, cleaned up my grounds, draw tested it, and added an extra ground strap to the alternator. the thing is, the alternator will charge and everything just fine for about a month or so and then BAM, it just stops charging. more specifically, what happens is when i crank up the car my cold start assist comes on. while the car is idled up the volts read at about 12v or so. when the cold start assist shuts off the volts jump back up to about 14v or so like it should be. when the alternator goes out, the volts wont jump back up after the cold start assist turns off, it just stays at 12v. i have the cd player hooked up directly to my battery since i didnt know where to pick up a harness. could this be a problem? Anyways, sorry about the rant but im about ready to sell the car if i cant get this problem fixed because alternators are expensive!! thanks for any help in advance!