Notice the cranking amp rating is "PEAK" amps. Likely the highest instantaneous reading which is not comparable to the standard CCA rating which I believe is the hight amperage sustained over 30 seconds or something ridiculous like that.
If u like that concept get a light weight Braille (10 lbs or so) and connect a flaming river electro-wizard. It automatically cuts the battery when you turn off the vehicle so it doesnt go flat from any draw from the vehicles electrical system. Pretty cool device actually.