Charging System

[Just me]

I have this problem with my charging system. Every time I drive the my car for a while, it won't crank up again. The motor just gives 1 or 2 turns then stops. I've checked the battery and it felt hot. It's 750 cca and is trunk mounted. There's corrosion around the negative post and the positive cable gets hot. The battery, starter and alternator are new as a result of this problem. When the car has cooled down it starts up like the first start of the day. I don't use the AC,heater,or defroster. I have an aftermarket stereo and speakers that all seem wired up right. I do notice that when I drive at highway speeds, that the voltage needle is above center. Can someone help me? I have other problems I'm trying to solve like mysteriously missing coolant and a picky alarm system. Thanks.