In Iron Man Obadiah steals Tony's arc reactor which leaves him with the Mark 1 chestpiece (which he puts in his body so he can survive).

If he only has one arc reactor, and he's using it *in his body*, how does he manage to use his Mark III suit? 

[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/qVCEt.jpg