Electrical Issues

Hello Everyone,

About a month ago, I was having issues with my car not starting. I had to jump the battery every time I wanted to go somewhere. Eventually I would charge my battery with my battery charger over night until I replaced my old battery with a new yellow top optima. I know they are probably overrated and not worth the cost but I didn't want to take any chances with battery issues since I know how big of a pain they can be. When I put the new battery in, I was experiencing the same issues as the old battery, so I scraped the battery posts and battery terminals with a metal brush to expose new metal, applied dieletric grease to the posts and terminals, and refreshed my ground connection. After all that the car drove great.
Fast forward to last night I drove my car home from work with no issues. This morning, I go to start the car and the car is completely dead but the gauges act all crazy going through their full range. I jump start the car to see if that will start it, and it does. Same issues as before I changed my battery. I take off and for the entire 30 minute drive to work, I kept loosing voltage and the car would "shut off" for brief moments before coming back online. This would happen if I braked, used my turn signal, put the windows up or down. See attached video. sorry its not rotated.
View My Video

I'm thinking I have a bad ground from the negative post of the battery or the alternator is shot.

I am thinking about taking this opportunity to upgrade the whole charging system, ie. HO alternator, big 3 upgrade, and new battery terminals as I am into car audio. My current system is approximately 1500W at full volume

Any help is much appreciated

Edit: VDC with car off = 12.5V
VDC with engine on = 14V
Therefore alternator ruled out as root cause

next theory is to clean up terminal to post connection.

 

Cleaning of the battery terminals and posts with a wire brush and contact cleaner and tightening the nuts has solved the issue. Sorry for the red flag
Sincerely,
- newb.