Bad Alternator or Big Short?

[Clutch450]

So for the back story:
I went on a spirited run a week ago on a back road near my house. When done i pulled over and noticed that there was smoke coming from under the hood. Around the alternator oil filter area.

Nothing seemed different with the car, but when I would start it up in the morning the brake and battery light would stay on. Meaning a bad alternator correct?

Then two nights ago the car would not stay alive. It would drive but would not idle long. Lights very dim, Radio keep switching on and off. Until it finally just died.

So i replaced the alternator from a known running car(alternator has been sitting for 5 months now though)
Put everything back together and its doing the same thing. Too much of a power drain, (lights, radio, windows, etc) cause the car to die out.

At idle im only getting 12.4-.5v and dropping from the battery
At the alternator im getting the same volt reading.
Battery is an Optima Yellow Top
But i am not getting the brake and battery light to stay on when started up

Things are pointing towards a bad alternator but could this be since 5 months ago this alt was working just great?
Could my battery being so low have killed the alternator when I put it in at first?

I am going tomorrow to get my alt tested but I wanted to post this up here to see if anyone could give some insight onto the topic.

Sorry for the long post, better to say everything now then answer questions later.

Thanks!

 

[U8NTRDY]

Generally, If the car will start but won't continue running its usually the alternator however a battery with a bad cell or two could also add to the issue. If you wanna be cost effective about diagnosing this, you should first get the battery tested. Its a free service offered by most auto parts store. If the battery is known to be good, then replace alternaator with a new one. You can get a new alternator relatively cheap, as low as 70-80 bucks some places. You should be getting 14.4v at the alternator.

 

[And_44]

Could be just both have a bad voltage regulator.

 

[Clutch450]

Alright, So when I take the alternator in to be tested tomorrow I will have the battery tested along with it.
And 13.4v at alternator?
I thought it should be in the 14v range

 

[And_44]

Also true about battery. Had a post from battery that was broken internally and had almost same symptoms. Forgot about it until he mentioned it above.

 

[Lou98GSX]

yes it should be at least 14.5v . make sure that the large wire to the alternator has power if it doesn't check your fuses .

 

[U8NTRDY]

Alright, So when I take the alternator in to be tested tomorrow I will have the battery tested along with it.
And 13.4v at alternator?
I thought it should be in the 14v range

Typo sorry. 14.4-14.5

 

[Clutch450]

I checked fuses they are all good. Not one blown.
I did notice that the previous owner installed am extra power feed wire for the alternator. A huge 2g wire with no fuse. Leading from the alt right to the battery.
The original two white wires that lead to the fuse box are still there.
Should I eliminate this big wire or at least put an in line fuse in there

 

[miguelmcv]

Keep the Big wire and just add a fuse, The white double wires might be bad, If he add a new wire, then it's almost sure that the stock wires are not in good shape.