This week my battery and brake dash-light came on and I noticed the battery guage reading a little lower than normal.
Had the alternator checked at Autozone and sure enough it was not charging at fill output. Battery checked out good.
Bought a re-manufactured "Duralast" and swapped it in. No issues there. Went to start the truck and within a few seconds both dash lights came back on and the battery guage was pegged at 18V.
Checked the battery with a DVM to confirm and was getting 18.5V and climbing. Smelled burning and shut the truck off. Alternator was hot to the touch.

Either regulator in my brand new alternator failed (or was DOA) or I have a wiring issue.

So questions:
Could something be (suddenly) shorted that would cause the regulator to instantly fail?
Is it just coincidence that I replaced an alternator with a bad one?
I don't have an issue exchanging this one but I don't want to risk of frying a second alternator.
No issues with the truck or charging circuit other than the original alternator getting weak.
I do realize I rolled the dice on one of these Duralast re-man's. I've used them before on my other cars without issue but perhaps I should get a NAPA one?

I'm a little nervous that there might be an electrical issue but fuses and everything appears to be normal.

'91 22RE pickup.

 

Without knowing your vehicle I’d lean towards a bad alternator. Can you return it and get your core back? Good chance it just needed brushes, and you can get a brush holder assy with brushes already soldered in.

 

Auto Zone's Duralast remanufactured alternators are rebuilt by Remy (formerly Delco Remy), which has a fairly good reputation for these parts. I cross-referenced the part numbers with those available on Rock Auto and they match up. Likely Remy just puts them in a Duralast branded box for Auto Zone.

It's always possible that the regulator in it (which appears to be solid state) was faulty or defective right out of the box or possibly not connected correctly inside, it does happen. Since Auto Zone gives you a 1 year or Limited Lifetime (depending) warranty on it, they should give you another one.
I would however insist that they put it on their test bench to verify that it is properly functional before you leave the store.
If they aren't willing to do that get a refund & look elsewhere for one.

I personally do not like to buy parts from NAPA because their prices are usually far higher for often the very same item.

 

I have little to no faith in any electrical item sold by most chain parts stores. At least what they have on the shelf.

 

Make sure your "s" wire is good all the way to the fuse block and that fuse to battery is also good.
If S wire good, then it must be the regulator. Search forum for how charging syatem works.

 

Dropped a new alternator in and it worked fine.
Back in business.