Battery and Alternator question?

The amps are usually stamped into the case. Yes 1k per year is a little tough on you battery. 5-8 years is normally the life span of a normal battery. If you had a solar panel(trickle) 3-5 amps in full sunlight, it would extend the life of your battery. Put a cig lighter end on the panel, and plug it in your cig. lighter, and the panel on your dash. I use this set up for my RV works great. Yea, the sound syst you are talking about is a real energy hog. Being you use the veh so little, maybe a second battery would be a better approach. wire it in Parallel(pos to pos, neg to neg) and it will double your amp hours, and the solar panel will keep them both fully charged, all the time. Usually a substantial amp rage(alt) upgrade will give you a headache due to a larger frame alt, which will have to have modified mounts.