i have a bad alternator and a new one in the mail. The odd part is that my old alternator starts out making 14.6 volts on cold start every morning and slowing drops until the voltage gets low enough for the break and battery lights to come on. So my question is why isnt it just dead all the time?

The cars a 97 legacy 2.5l, not that it really matters

thats easy. Ask more how does electrical components fail. When the componet is cold, dimensionally and electrically everything is making contact. As thigs get hot, they expand, and if there are any weak connections, will open up.. Also heat is electricities enemy. As heat rises, so does internal resistance (less electrical flow in the wires). Also with age and heat insulation breaks down, and instead of using the full winding, may be using part of it, so less energy output. ALso its possible for diodes to go open when hot etc etc etc.

 

hope that answers your question

 

 

nipper