hi friends, last year we used one of the batteries from OPTIMA Batteries. It was 41Ah, CCA-550, CA-650. the biggest problem was the weight cuz it weighed around 13Kgs!!! This year we are planing to use a smaller battery. With all the systems running simultaneously, the current required would be 15-18Amps(without the alternator charging). What are the ratings we should look for?? What are the typical ratings for CCA & CA??