DanEC Dan first off IF your motor is running a 65 amp alt without under driven pulleys, this output is fine. Here's a basic list of draws in the charging system in amps. It's not perfect but close
Electric fan (1) high speed 8-16 amps
twins fans in front of car 7-15 amps
wiper motor depending on speed and load 5-12 amps
lights headlight, (Old style) 2-6 amps
Stock ignition with
oil coil about 2-4 amps
rest of electrical draw about 2 amps running max.
The biggie, CHARGING of the battery, upto MAX of the output of alt.
voltage may go to 16.0v depending on battery and condition
The wiring setup for the cobra was to run a 45-60A alt setup.
Today is different with alot more power users in the car
MSD ignition system may pull upto 10amps alone
Electric fuel pumps depend on unit 15-18 amps
Some guys have AC in their cars, add another 30+amps
High power HID lights, They are all over the place with load.
At idle you need about 30 amps to power the system and recharge the battery. Any thing less and you are looking for problems. I went through this many years ago. Main problem was underdriven motor pulleys and killing the battery at idle. I also started to melt the end at the Alt, just like yours. The worst part was the insolators on the amp gauge in the dash. They where melted too. I couple of guys here have melted there wiring harness and it not a good thing. You could loose the whole car.
Here's what is in my car and what I did to fix all the problems,
PAperformance sells a couple kit for cobras with a 95 amp setup. This is more than enough power for all the acc to run at idle. It has a old style regulator box and Alt. Change 2 wires and you are done. The other issue is to replace the Amp gauge with a volt meter. The 2 wires that are connected to the guage should be spliced togeather and add 150 amp maxi fuse to protect wiring system. Swap the pulley off old Alt. Been running this system for 5 years and no problem. Still can run the under drive pulley from march on the crank shaft. I went to a 1-1 ratio with crank and water pump for another problem. My system runs 35-38 amps at idle and 14.12 volts on the gauge. when all the electric is on still in the 12.7 volts.
Power load to my car, FI system with injectors, 2 fuel pumps (electric) MSD ignition system with HVC coil, 6 cooling fans, 3 for the motor, and 3 for removing hot air from under the hood and down the trans tunnel. Total load is about 48-52 amps depend on temp of the day. This can be a 2-4 amp extra.
I would check out the wiring behind the dash at the amp meter. Make sure the insolators are not burnt or off color. Any possible thought, REPLACE THEM or the gauge.
Only other thing I did was add a fusible links to the main power wires. If you have a dead short they will save the rest of the wiring. Need about a 125 amp. This is what I run. Gives piece of mind. Good luck Rick L.