In Iron Man, it is obvious that Tony Stark's chest-mounted ARC reactor serves two purposes:

  1. Keep the shrapnel out of his heart, and
  2. Power the Iron Man suit.

However, in Iron Man 2, we see that the War Machine suit has an ARC reactor built into it.

Jarvis indicates in IM2 that increased use of the suit was leading to Tony's chest-mounted reactor killing him. If he could mount a reactor directly into the suit, why does he continue to use the chest-mounted reactor to power it? Why not put the ARC reactor into the suit and use something less poisonous to power the magnet keeping the shrapnel out of his heart? Was an explanation ever given for this?

  • 4
    Possibly not a dupe, but very much related: Why did Tony Stark build arc reactors into his extra Iron Man suits?
    – phantom42
    Commented Apr 24, 2014 at 14:16
  • As far as we know his Arc Reactor was the only thing capable of keeping the Sharpnel out of his heart indefinitely. Switching out the entire Arc Reactor entirely for something else would most likely kill him. Commented Apr 24, 2014 at 14:52
  • 2
    @DoctorWho22 Not true. In IM1 Tony has an electromagnet powered by a car battery, so clearly something else could be used.
    – Shadowman
    Commented Apr 24, 2014 at 15:33
  • 3
    @DoctorWho22 I highly doubt the FIRST device in his chest was a prototype Arc reactor. Yensil is the one who put it in there while Tony was unconscious. Tony later built the prototype reactor and used it as a replacement.
    – Shadowman
    Commented Apr 24, 2014 at 15:45
  • 1
    It wasn't a prototype arc reactor, but a coil magnet. And that too was fairly insufficient. That is why Tony built the prototype arc reactor. And @Shadowman, it's Yinsen.
    – Stark07
    Commented Apr 25, 2014 at 6:36

1 Answer 1


1. Why there's no alternative:

He cannot use anything less poisonous up until the point he re-discovers the new element that Howard Stark had thought of.
At one point in the movie J.A.R.V.I.S. mentions that

"I have run simulations on every known element, and none can serve as a viable replacement for the palladium core. You are running out of both time and options. Unfortunately, the device that's keeping you alive is also killing you."

This means that there was no "something less poisonous" that he could have used.
Also, There are no other clean energy sources that could've generated the amounts of power required by the magnet. This was significantly bigger than a pacemaker, so he couldn't have used a battery of that sort. And no battery could've given him the levels of energy required for the magnet. Plus the arc reactor was already integrated into his chest.

2. Why he doesn't continue wearing the suit:

J.A.R.V.I.S.: It appears that the continued use of the Iron Man suit is accelerating your condition.

Using a suit based reactor would mean he would have to use the suit more often, which would have in turn worsened the reaction to Palladium, as seen from what J.A.R.V.I.S says.

Also, another reason he puts the reactor directly into his chest is so that he doesn't depend on the reactor in the suit for life support.

  • 1
    During captivity in the first movie there is a non-arc power source keeping him alive (a car battery as I recall). There are plenty of smaller power sources capable of generating that level of power in real life that he could have used in place of the arc to hold off his poisoning. Certainly not to power the suit, but if his life was on the line you would think he could have lived with two different power sources (one for him and one for the suit) for a while. In fact, by IM2 he already integrates reactors into the suits.
    – Nicholas
    Commented Oct 9, 2017 at 14:59
  • This doesn't really answer why he doesn't have a low-power/long-life/low-toxicity reactor in his chest to run the electromagnet and a high-power/short-life one in the suit, instead of running both suit & magnet off the same power source - especially since he has to keep swapping out the core. As an engineer, multiple redundant power sources should have been one of his first solutions. Commented May 24, 2018 at 15:48
  • IIRC, the magnet was originally powered using a car battery, back in Iron Man 1. An arc reactor was certainly not the only power source capable of generating enough electricity to keep the magnet energized.
    – Ajedi32
    Commented May 20, 2020 at 15:20

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