Okay so I joined to get opinions/facts from others who love car audio to in full understand what, and why. For starts, I have all old school components, minus head unit, 6.5’s and 1 10” sub. (Quantum Q1500/10S subs x2, QS1500D amp and QA2160. My car is a 06 cobalt LT with maybe 7 month old 110A alternator and 2 batteries, ones 3 months old other is maybe 8. QA draws 30A, QS draws 100A power. Volt meter helps monitor. Alt jumps between 14.1-15.2 when first started. Drops to 13 unless something was left on or amps playing. both have VD under my cruising sound level (not clipping or distorted, but not anywhere near low). I only run one system at a time, as there separate lines. With the QS on, sometimes my alt stays steady Feeding power with a .5 max VD To car. Others, under bass drop. I’m down to 12.8, lights dimming to hell, windows barely rolling up, car trying to stall if at idol. QA sometimes gives me .2-.4 VD (my alternator is weird with its feeding power, can’t say what exact volts as I always see 14.1-15.7 max) now. I want to get opinions on WHY. Why the voltage jump at different times with alt, why severe VD, why do I sometimes run 13.3 max unless cars restarted and others 15+ with QS thumping, next to no VD. just. Why... Ground is great, sanded, self tapped, below that 18” length and branched by ground distribution block, good and snug at amp whole 9 yards. 4g AWG OFC to QS, 8AWG CCA to QA. Both amps are AB so of course there’s heat, but not thermal overload (protect mode) amounts no matter what volt. If we can’t piece together why on here, other than new alternator as I just don’t have the money for a high output one. Can we figure out a how to make it better and chill out that VD a little. Whatever you need to know just ask and I’ll relay the info. Just please, anybody. Help me further understand what my issue here could be.