Love this idea.Available ship sensors would include: thermal, relativistic, X-ray, and possibly radio waves. Sensors are used for detecting ships throughout the whole system (think long distance). Visual cloaks are useful for cloaking ships in the player's line-of-sight (think short distances). You would be able to equip more than one sensor on a ship but use a hard point for each sensor. This would keep your ship from being able to detect everything.
I also think it balances ships as they must have a good spread of technology. Or they can be brutes (just weapons + lack of sensors/ other technologies), but they can't hit without a good sensor kind of idea... It encourages you to keep up with your fleet and continue diligence and exploration to get the best possible technologies.
Agreed.Maybe something along the lines of a cloak that completely masks your ship, but depending on how much heat output it has, the cloak starts to glow and you see an outline of the ship. The more heat produced (weapon fire, engine use, internal reactors running) the brighter it'll glow. This would allow for ships that go into 'silent' mode to drift through enemy territory without being seen, but would prevent an assault from a capital ship because the engines would be putting enough heat out to stress the cloak.
Of course, this also adds a bit of strategy too. If you really want to take the time to try and drift a huge carrier into the middle of an enemy faction in order to do a surprise attack, and you're willing to spend a week to do it, I see no problems that way.
I also agree with the side that think it should drain energy, and it will likely be part of the "generator" category in the ship's hardpoints. I think it would be effective to create stronger cloaking objects versus stacking cloaking objects, however if you'd like to stack, you run out - your ship is stranded out in battle.
I'm leaning more towards this option as a strategical means of surrounding or sneaking up on an enemy, not an endgame ability. The enemy always has a means of finding out where you are, depending on how advanced their technology is