I have 39 years of experience in a shop that did automotive electronics as well as wide are LMR radio systems. i then went on to work for Kenwood (then JVCKenwood) as a field tech and later R&D engineer.

How does that tell me what is wrong with your car? The ONLY way to find what is going on, is to measure the current flow at the battery and go track down where it is going. It is a fundamentally simply procedure that works in most cases (tho I did have an SRT in Georgia that had a fault in the main B+ lead to the chassis that the owner didn't want to spend the money to trace - they sold the car instead.)

My procedure is on this site somewhere, if I can find it I[ll link to it. I also have it on my PC here at home, but my Word license is corrupt and Word wont let me copy or even open the text....