so I have read a bunch of other post and see that the cause of my problem it either the battery, fusible link or alternator.
Here is what happen I was driving on the freeway lost the radio first then the power steering then the car shut off I just made it to the edge or the freeway I was so close I had to get out the passenger door. Tried to start the nothing, had it towed home.
Check the battery it had 12.4v tested the alternator bad. Bought Denzo from NAPA installed it car started but overvoltage (18.4v) while car was on returned it tried new alternator car was good for like 3 months. Wife took 6 hour road trip when she got back she said she heard a pop looked under the hood did not see anything no burn smell nothing car ran fine the next weekend took another 5 hour drive on the way home power steering got tight ten minutes from the house. next day car won't start charged the battery started the car read over charge 17.5v on alternator and read 11.5v and dropping all the way to 7.6v on battery. This is when I started checking fuses that's when I found the fusible link burnt(never installed the cables backwards). I check it the first time and it was not burnt. My question is do I have to swap the harness also. If you can think of anything that I should check be for I start the car let me know.

As for right now
I tested the battery its good 12.9v
The alternator will be tested tomorrow
bought a new fusible link bar

 

Did you check the connections at the alternator? Something can be shorting out. Don't they have rubber protectors at the post?

 

Thanks I will check when I reinstall the alternator today.

 

Always good to take sandpaper to those contacts

 

I do not know this specific car but Toyota and Mazda allow one of the on board computers to tell the alternater how much current to put out.
Point; if the feed back loop to the engine ecu or body control module is compromised and not seeing battery voltage due to a bad connection or intermittent wire, the computer will tell the alternator to increase the current output and create those crazy voltage spikes. Nothing is really meant to be above 15v so 18 could damage components.

If this is the case, it could explain your voltages being all over the place potentially with blown fuses and burned links. I think a deeper dive of alternator circuit to ECU/BCM would be wise (if they did it this way???) An actual schematic would be a life saver!