Alternator- Is it going?

So I am still on my OEM alternator. I have read that they are actually good for over 250k miles. I am at 180k right now.
I was doing regular battery checkup and noticed my battery was at 12.6v resting.
At idle, it was at 13.8v.
I then turned on the AC, lights and stereo and it fell to 13.5v. I switched the load off and it showed 13.6v and stayed there. I even gave it throttle to about 2000 rpm, but it stayed at 13.5V/13.6V
Is the alternator not able to fully charge the battery? I am told it needs to be between 14.1 to 14.7v.
Signs of eventual failure?
Battery was changed in 2021 March.
I do not have any day to day symptoms and the truck runs fine.

 

Could try cleaning battery terminals and see if that helps. Might also be the battery as it is getting older.

Just measured mine (2019 SR5, 63K miles, fairly new battery):

- off: 12.5V
- idle: 14V
- idle with lights, radio, and AC: 13.89V

 

I will clean the terminal again but they look clean with no corrosion. I fluid filmed them last year.
Strangely , when I checked last week, it showed 14.0v at idle and stayed there. And barely went down with any load.

 

One of my someday goals is to build a data-logger for vehicles that will log things like battery voltage, transmission temp, etc. and then graph it. I already do that for computer systems I manage -- would like something similar for vehicles. Already have a start of CAN functionality, but have not tried looking at vehicle data yet:

https://docs.simpleiot.org/docs/user/can.html

 

The brushes need to be replaced at that mileage. $20 from wherever. Toyota (Denso?) uses the same type brushes across many models. If you're able to remove the alternator, you're able to replace the brushes. It's very simple, and the new brushes will net you an additional 150k-200k miles. The alternator itself will last a long time. But you'll have to order the brushes, as it's unlikely anyone stocks them. I've made this a preventive measure on my vehicles.

 

If I have to remove the alternator to replace the brushes, should I not just go ahead and replace the alternator?
I am going to pay some one as it is to remove the alternator.

 

Well, if you have a buddy who can do it for cheap, you could do that. Maybe have him replace the serpentine belt while you're in there, since you have to remove that anyway. People often have trouble with reman alternators. A Toyota reman is around $330, and new is $500+ from what I see. Brushes are $20. My suggestion was based on DIY. I personally haven't had an alternator fail for any other reason, and 180k miles is typical for them to need replacing.

 

I’m not sure I’d be putting fluid film or (or even dielectric grease) directly on terminals, if that’s what you did. You need clean metal to metal contact.

 

Have you taken it mudding in those 180k?

 

I second just replacing the brushes.

 

I did put them on the battery connectors directly. A very thin layer last year. I was told it prevents corrosion.
It's pretty much gone but still looks ' lubed'. I can clean it if required.

 

No, only urban driving. But 2 years ago my oil filler gasket leaked and oil dripped out around the filler tube, down close to the idler pulley and next to the alternator. I am thinking maybe that oil seeped in some. Don't know.
What is surprising is, 4 days ago when I checked, it showed 14v idle and with all the accessories on it still stayed at 14v. But then now it's at 13.6v

 

I am told I would still need to remove the alternator to do that work . Since I am going to be paying someone to do it for me, might as well pay for a new alternator.

 

As others have said. Stop putting anything on the terminals. USUALLY corrosion is the gas leaking from the terminals and is the beginning signs to replace your battery

 

I would give it a try before spending money on having the alternator replaced. You’d hate to still have the problem after that!