I have a 60 amp alternator and 140 rms amp on it drawing what I would equate to a 20 amp draw. Now what doesnt make sense is that the alternator I have is a 60 amp and was only a year and a half old and from the nissan dealer. I was using a dual chamber abc box and it was very sloppy in car but I straightened it out with a 18 db per octave crover on the amp. Now the strange thing is I had to turn the low pass filter almost all the way up to make the bass tight and believe me it was. My bottom line question is since the amp would technically clip without the filter set the way I had it was I just masking it and causing a very hard draw on the alternator with a horrible signal of some kind and that blew the alternator? I know you no your stuff so your insite is appreciated.
You can easily check the alternator. With the engine off, using DMM, measure the voltage across the pos and neg. It should be somewhere between 12.5v - 12.8v. Now with the engine on, measure it again. Look for a reading of 13.2v - 13.8v. Now turn on the amp and monitor the voltage. If it stays around 13.5v, then the alternator is fine. If it drops to 12.5v or fluctuates up and down between 12.5 and 14.5v, then you will need to have the alternator taken out and get it tested. Most likely a blown regulator on the alternator.