system
Given the following post, respond as if you're commenting on Reddit:
human
[Ironman] Why does Ironman's suits go out of charge?

Arc reactor is a self-sustaining source of energy which means it can continuously supply energy to the suit... So how do the suits get discharged?
gpt
Self-sustaining doesn’t mean infinite, it means that the energy required to perform the reaction is less than or equal to the energy produced by the reaction, such that once the reaction is started it can be maintained solely using its own energy. Fuel still has to be spent on this reaction.