Good evening folks,

I'm owner/slave to an '83 245 DL wagon:
Fuel Injection
Factory clock
I believe the alternator/regulator is original (18 years old)
Cannot read the model numbers on the alt/reg (both ate Bosch The reg is mounted to the back of the alt, approx 1"x2", horizontal, towards the bottom of the alt and has one skinny red wire

Had a new engine wiring harness and a used computer installed a couple of months ago. My friend and mechanic that did the work passed away about a week afterwards I'm without a trustworthy mechanic at this point. Hence, trying to do this myself.

About two weeks after having that work done and while driving in clear and cool weather, the headlights go black, the gauges dump, and the car starts sputtering until it loses power completely about 10 minutes into the ride.

Next day, after sitting for 12-15 hours, she starts up, and does the same thing after running for about 5-10 minutes.

A week later I try it and it starts. I ran it for only a few minutes. I did not run it long enough for it to die.

Was not able to test it again for a month or more, at this time the battery was completely drained.

Had the battery charged today, supposedly it's in tip top shape. Hooked it up and she started fine. Tested the battery with a multimeter and while at idle it read 12 volts. With the engine running above idle it read 12 volts.

My understanding is that the battery should read slightly above 12 volts while at idle and above idle. This leads me to believe that the alternator is not charging the battery

Question 1:
Will a battery that has been partially drained re-charge itself to some degree?

Question 2:
Could this be something other than the alternator?

Question 3:
If it is a faulty wire, how to check?

Question 4:
Is there a SIMPLE way to check the alternator/regulator with out taking stuff apart?

Thanks,
Heidi