Having what looks to be an intermittant charging problem. Battery age approximately 6 months, don't know how it was treated by PO in this time as I just bought the car.
I encountered a problem where the battery light came on while I was local driving last sunday, so I brought the car home. I hooked my multi-meter up to the back of the alternator, positive to the stud with the wire bunch and negative to the braket mounting bolt. It looked to be not charging at all. Tryed testing from the battery as well and same results. below 12v and dropping while engine running.
Funny thing now was that I charged the battery back up and tested it again, and now it seems to be working again. It gets just over 13v at idle and 14.21 consistently at off idle all the way to 4k rpm. Its a Motorola and looks to be pretty old. I am thinking that it is dying and maybe on its last leg. I'll have to monitor it to see where it goes.
What do you think? Is there a more definitive test? Could a weak battery cause the alternator not to charge?
There is also what looks to be like a thick black epoxy of some sort that was leaking out of it at some time, but it is dry and hard now. I have attached a picture.