I have a 2011 Cruze ls. I compete in car audio a little bit and I think I might be having some battery/ alt issues. The amplifier is a 4k rms amp at 1 ohm. Last time I clamped the amplifier I was only getting 2k rms to the subwoofer, which is fine. I Started out with just the wet cell battery under the hood and the big 3 upgrade with 1/0 ofc wire. Stock battery wasn't going to handle that obviously, so I put a 100ah Deka agm group 31 in the trunk and grounded the best I could in the trunk. Should I run a dedicated 1/0 ground to the front battery, would it make that much of a difference? Anyways, last week I replaced the wet cell under the hood with an XS Power D4700 agm battery. So now I have two agm's. I put my NOCO 7.2amp agm charger on the deka in the trunk to charge them both (I dont know if it matters which battery I charge it at, I wouldn't think so?) Now I have both agm's fully charged resting at 12.9v. Here in Indiana its been in the low 20's so I know the alt likes to charge around 15v. So with the low temps, two fully charged agm's, the alt still charges 15-15.4v pretty much anywhere I drive. As far as I know agm's dont like charging that high. I also thought that since the computer regulates the alt, it would recognize the batterys are fully charged, and wouldn't charge as high. Of course the amplifier doesn't like seeing 15v and it goes into protect. If I warm up the car (warm the amp up some) then restart the car and immediately start jamming to get the voltage down some, then it's fine and slowly climbs to 14.9-15v again. Sorry for the lengthy post, I'm just not sure if this is really okay or not. Any advice would be appreciated.