Dave is right,

In order to utilize the full 30amps discharge, you need to use regenerative or external load. I would go with the regenerative route since you need quite a lot of low resistance resistors and lots of cooling or 12V spot lights to get 30 amps.

What people do is they hook up the charger to their car and turn on the radio and lights to simulate a load and regenerative discharge their pack back into the car's battery.