system
Given the following post, respond as if you're commenting on Reddit:
human
[Iron Man movies] How is Tony Stark able to use his gauntlets independently if they are powered by his arc reactor?
gpt
By the time of Iron Man 2, all of his suits had personal arc reactors retrofitted into them so that people other than himself could use them.

By Iron Man 3, he had started experimenting with suits that broke into separate segments, so he built temporary power packs for each piece. He must have miniaturized the arc reactors further to allow for long-distance travel while separate the way the Mk. 42 did. He also experimented with single-shot repulsors that burnt out after one use.

He must have taken the lessons he learned from the Mark XLII and applied them to the War Machine suit and his new Iron Watch/glove, miniaturizing the power further to allow Rhodey partial suit use and himself an emergency weapon good for more than a single surprise blast.