A

I use all vehicles.

I want capacitors mainly to hinder vehicles using the weapon meant for another races vehicles. Particularly with tanks this would make it so that a Caldari tank with a rail turret would matter. A Gallente tank with a blaster would be able to fire longer before overheating. An Amarr tank would field a laser more efficiently and a Minmatar could get more close up bang with a projectile turret.

Also, this would make a big difference in the use of active vs. passive modules relative to the power of the turret. Just like in EVE you would have to choose between active defense vs. firing a proto turret. When you are on the offense you are weakened on defense and vice versa.

This would decide whether a tanker lives or dies. Make the tank powerful so long as you can manage the cap. If it burns out you dead baby!

I'd rather not have yet even another way to hinder vehicles even more, unless it's not that bad. Plus, how would you fit repairers and boosters into it? those are the things (other than nitro and afterburners) that take up the most cap, so what would it be? turrets? you want turrets to have ammo, overheat, and then cap? No, that's stupid.

Capacitors work like stamina. Think of it like a battery that is constantly recharging itself. Some modules are passive and don't draw down the power, and other modules use power when they're switched on. So if I run the scanner constantly it will drain the battery down to like 80% where the drain and recharge reach an equilibrium. Some modules may completely drain the battery when running non-stop (a powerful armor repper for example), so you have to use it in bursts (like your sprint button and stamina regen). When your cap is empty all active modules are switched off until the cap recharges back enough to turn them on again (just like you can't sprint until some of your stamina recharges back). This allows drivers/pilots to manage which modules they want to run, when they want to run them, instead of having to wait out really long cooldowns.