This is not a vehicle related issue, but I am hoping someone can help me. I have a homemade portable sterio system (4 speakers, amp, ipod) encased in a rolling cube cooler that currently runs off of an Optima deep cycle battery. It works great and lasts approx 12 hours before needing to be recharged. The Optima is 12v, 55Ah. However, the Optima battery is about 45 lbs, making the system quite heavy. I am looking to reduce the weight of my battery without significantly reducing my length of play. From my research, I believe that high amp hours are what I am looking for.