Battery Drain is the measure of how much and how fast an item will drain the cars battery. There are two types of Battery Drain: kW/use and kW/sec. An item that drains X amount of kW/use will use that much when activated. If there is not enough kLiM left in the car, the item will not activate. An item that drains X amount of kW/sec will drain that much for as long as it is active. If there is not enough kLiM left in the car, the item will deactivate, and then automatically reactivate once there is enough charge.