Dimming lights, altenator or battery?

[tino0217]

I have a 71 c10 with a 350, i noticed when i bought it that the lights would get brighter when i accelerated. I replaced the altenator (70 amp) but still does it. I started using a 760 watt Schumacher power converter and i have it running thru the lighter to plug in some 110's. I installed a stereo system, 250 watt Kenwood with 500 watt speakers, nothing fancy. I took my home theater subwoofer which has a 110 plug in. After a couple of minutes of sitting idoling the coverter statts beeping saying low battery. I installed a 100 amp altenator last week and the lights are still dim til i accelerate and the converter goes about 5 to 10 minutes before it indicates low battery. I also have a battery kill switch. With all that said, it my battery? Battery is 700 cold cranking with 95 reserved capacity. Anyone have advice?