How to charge your suit in space engineers?
To charge your suit in Space Engineers, go to a medical room's terminal and hold T
Obviously, you have to be producing energy in order to charge it.
Your suit will also charge while you are sitting in the cockpit or any of its variants or passenger seats of a powered ship or station.
In addition to the answer by @user9239425 (using a healing terminal). Your suit is also charged when you are in the cockpit of a powered ship.