"Heavy cloaks will take up 450 cargo space, available to ships with 1100 cargo or higher. Having a charge time of 60 seconds, and a consumption rate of 1 battery per second will give any ship with large cloaks ~440 seconds of active cloak."
This calculation seems to be off: 450 max ammo limit - 60 ammo needed to charge the cloak, and 1/sec consumption = 390 seconds of active cloaking.