I've had my P3D+ for a 4 months and put 3000 miles on it. I'm pretty familiar with the sounds it makes like the inverter cluck under the back seats.
I experienced something totally different last week. I was on a road trip. After about 75 miles of driving (second leg) at freeway speeds (in southern California; outside temp was about 55) we needed to stop at the super charger. One spot open at supercharger, so was getting about 60 kw. After about 5 minutes of charging, we heard a loud noise under the my feet (driver foot-well). It sounded like something between an explosion and hitting the bottom of the car with a sludge hammer. It was loud enough that Me and the two other passengers jumped out of the car to see if something exploded. Everything looked fine, so we got back in... Charging continued. about 5 minutes later, there was another similar sound (but more like a metal cookie sheet popping in the oven), it was not nearly as loud and also sounded like it was from somewhere near the front of the car. Continued charging another 15 minutes with no additional odd sounds.
Since this is my first/only time super charging, is this something other people have experienced? It was quite startling and if this is normal, i'll need to warn passengers at the super charger.
I have a server appointment next week for something unrelated, so thought i'd mention this and get it noted on my car's history.