This question already has an answer here:
Correct me if I'm wrong. Before Tony created a new element, or maybe before Iron Man 3, from what I understand, the Iron man suits are powered via the Arc Reactor in his chest. How was Rhodes able to use the Mark II?
Or to further my question: When did Tony build Arc Reactors in his suits? Because from what I remember they still use the one in his chest from Iron Man movie.