The Mark XLII

I have some issues with the new Mark XLII in “Iron Man 3”.

Why does Tony insist on wearing it around the house after he threatens the Mandarin? It’s a prototype; wouldn’t it make more sense to wear one of the armors that work?

How is it powered? In previous films, the armors were powered by the ARC reactor in Tony’s chest. However, I do believe at some point the suits switched over to internal reactors independent of Tony’s chest piece. How do I know this? In “The Avengers” Tony uses the Mark VI for the first half of the film. By the time he arrives at Stark Tower, the gauges in his HUD are displaying warnings that the suit’s power level have reached critical level, indicating that it’s almost out of power. Tony then switches to the Mark VII and has enough power to last through the battle with Loki and the Chitauri. Therefore, new suit = new power source. Also, in “Iron Man 3”, Killian rips open the chest of the Mark XXXIII and a triangular Vibranium core is clearly visible. What about the XLII? Its ability to separate into smaller pieces would mean that each piece would need its own power source. If each piece it independently powered, why does it lose power over Tennessee? The Mark III was able to fly all the way to the Middle East using a single Mark II chest piece. If the Mark XLII does run off ARC reactors, then how is Tony able to recharge it using a car battery? I suppose it’s possible that the XLII runs off some new rechargeable power source, and not an ARC reactor like previous models. Why then does it have a chest RT then? Is it just for use as a weapon? Also, The suits require power equivalent to three nuclear reactors just to run for 15 minutes, so was he able to charge it overnight with a DIE HARD?

These are the kinds discontinuities and oversights that ruin a movie for me.