In the MCU it's implied that the arc reactor powers the suit.

We've seen that the replusors and the boots work on their own. They can function without the arc reactor.

In Civil War Steve stops Tony by destroying his arc reactor and therefore shutting the whole suit.

But since the arm and boots function independently he should've fought on.

Bump.

No explanation?

He was unable to keep pace with cap with a full armor and to try and engage him with only repulsors and one boot jet would result in him getting his head caved in.

@gazool: Yeah but if you watch the scene again you'll realize that the arms HD actually stopped functioning.

One repulsor blast from the suit was enough to keep Cap down for around 20 seconds. And he'd have all the time on the world to kill bucky while Cap is down.

I think it's just a story flaw or the only other explanation I can think of is that since it's a much weaker suit perhaps it's not designed for combat so it required power from the arc reactor.

Otherwise it just feels like a flaw.

Aside from ones created to function that way, like the one in IM3, and the watch gauntlet, when did he ever use the repulsors without the arc reactor?

@richubs: all things considered, I simply think, The suit was not meant to function that way.

I think it's because thus suit is lighter than the older ones were

@zubatcarteira: A random suit from IM 3 had that function when Pepper used it to blow up Mandarin.

It's pretty clear he built it for all suits. He even had it in Age of Ultron when Captain comes to the tower with WS and Wanda.

When he was making Mark 3 and the boots and the arm were completely separate from the suit. I think he'd carry on the basic design into other suits as well.

plot dude. Realistically there's no logical reason he didn't just bring back the sonic taser from IM1 can incap both Cap and bucky immediately. They still gotta make a movie.

The arc reactor also provides a majority of the power for his artificial heart. It has a battery back-up but it the majority of energy comes from the reactor. if he's on battery power, he's not going to be able to exert himself.

Even if he could’ve kept fighting (which I doubt he’d stand any chance at all without the arc reactor) maybe he simply came to his senses a bit after Cap thrusted his shield into his arc reactor rather than into his head

He was done. Mind you this after Cap just slammed him to the ground with the back of his head smacking a rock pretty hard, now his reactor is critically damaged, the emotion of everything that went down as well....he was just done, nothing left

@rl4: yea. The sonic paralysis devices were a criminally underused and overpowered weapon introduced in the very first MCU movie and then completely forgot about. So much could have been easily solved that that simple, tiny, non-lethal device. Hah.

I would not be surprised at all if he could resist it though, and it has to be put right up to someone's head (and the stun attacks used on Bucky barely slowed him down). Repulsors can be nonlethal and gives the user better range, so that's actually the smarter choice. It's just that Cap has a shield to block it when he charges at him, a suit made by Stark that can take repulsors, and superhuman stats.

There was so much PIS in that one scene just so cap could have a chance in that fight.

Suit was trash.

He was done. No repulsor would have saved him. His head was exposed means Cap could have killed him with a punch.

And there was no PIS involved either. Just 2 guys holding back.