What is the resting voltage of the kinetik with the car off before you ever start it for the day? Fully charged it will be 12.8 v or more and if your alternator can keep up your kinetik should be at 12.7v or higher. Looking at your set up if your alternator is 100 amps its a safe bet the car is going to need 40 amps from the alt to stay running or more with other accessories on so that drops your available power down to 60 amps for audio. For a 1200 watt amp that is 100% efficient it would need 83.33 amps to do 1200 watts @14.4 volts and as the voltage drops would need more current add another 10 to 15 amps for the other amplifier you are at 100 amps by the amplifiers themselves @ 100% efficiency. A 100 amp stock alt wont do 100 amps at idle (maybe 60) and it may not do 100 amps when hot ( I know mine doesnt and its rated at 100 amps ). I have a 7 year old kinetik 1400 that is the primary battery in my truck that powers anywhere between a 500 watt to well over 1000 watt systems in it and the only way I had drop to the 12v range is when I was trying to see how loud I could get a 1.12 cft sealed built to the cab box with a single 12 firing through bench seat and that was well over 1000 watts on just the sub.
If your alt max puts out 100 amps cold and @ highway speeds and your system can pull more how will it keep your car running and keep the battery charged?
I have never had an optima last 7 years in fact my first one died within 3 months and it did so in the judging lanes at IASCA World Finals in sq in 1997. After it died in the lanes it also would not take a charge after even if we disconnected it totally from the car. IIRC the battery was in the high 9 low 10v range. When I bought the truck I have now it had a less than 3 yr old yellow top in it (date was indicated on the top), I also figured out why a napa battery was in the bed. After I installed my system I could not do ANY engine off listening/tuning without my SS amp giving the low voltage squeal of death within 3 minutes so I put in the battery I have now. When you have to use a lap top to make adjustments to your audio system it isn't worth while to also contend with engine noise and leaving an intelligent charger on your car while tuning is not exactly good on the charger.
For your set up I would check your state of charge on your battery, check your grounds, get your alt checked, do the big 3 and then go from there. If you are having to pull 100-200 amps from your batteries which at 11 volts you would be how is a 100 amp alt going to run the car, the audio system and put back 100's of amps into the battery as fast as it can pull it out? Judging from your videos you are pulling alot more at idle than your alt can put out. If your are subjecting your battery to that it will lag behind. If your car is only putting out 100 amps max even when you are driving it down the highway you would be pulling from the battery often when the bass hits.
