One more thing I would check to be sure you are in the clear. Have your battery load tested. If you replaced the original alt for a no charge condition, then your new one fell the same way, be sure your battery is not defective causing the alt to go full field and burn out. Yes the new alt could have been defective or weak. I would suggest you get the battery tested to be on the safe side. I didn't read what year you have and if it is orginal battery.

James

PS Most anytime the voltage drops on the battery when engine running, the alt is putting out nothing. The voltage drop is due to the load from the electronics to make the engine run.