Normal Alternator Output

[Texas_4Runner]

I had to jumpstart my 4Runner so I drove it to O’Reilly’s and they said my battery was good and the voltage regulator failed.

I drove home, charged my battery to full, cleaned the terminals that were filthy. This morning it struggled to start but I was able to get back to O’Reilly’s. A different person told me the battery was bad. It’s over 3 years old so I put in a new one.

Then they tested the alternator again and said the voltage regulator still failed. I went home and used a multimeter and got the following numbers.

With 4Runner off 12.78V
@idle No lights 13.46V
[MENTION=21408]2000[/MENTION] rpm no lights 13.55V
@idle with lights 13.42V
@idle with headlights, radio, and AC on high 13.36V

I’m supposed to drive to MT tomorrow and I don’t really want to put in a cheap remanned Ultima alternator from O’Reilly’s. Based on those numbers the alternator seems to be working. And I don’t hear a whine.

It’s a 2008 V8. What are your thoughts? Should it be closer to 14V?

 

[itr1275]

First off the guys at O’Reilly’s get about 10 mins of training on this stuff, but they do have better equipment than a volt meter.

It is remotely possibly the the entire electrical charging system went bad at the same time. I've never seen nor heard of it but it "could" happen. i.e. they likely don't know what they are doing.

The numbers look about right it should be about 13.5-14V when charging. I doubled checked my 2020 4runner 5 mins ago and it's 13.9V while charging. The video below shows 14.5 - All the Toyota's I have had run < 14V.

Take a look at the voltage when you start the car too. The battery voltage will drop. Anything below 9-10V can be an issue with the battery.

Check it when you turn it off. Battery voltage should be ~12.5V. Let it sit overnight and check the voltage again. If it's dropped below 12 it's likely a battery.

This should help.

How to Test a Car Battery with a Multimeter - YouTube

 

[itr1275]

BTW you might try a different O'Rielly's or different source. The quality of customer service reflects 100% on the management.

Best of luck stay safe.

 

[Texas_4Runner]

Thanks.

The perk to living in the middle of no where is having only one auto store, and it’s O’Reilly’s.

 

[SilverFox2020]

If you have access to a load tester, that will tell you about battery condition and alternator performance. A battery may show 12 volts but not have the reserve to turn your starter. Extreme heat and cold shortens battery life.

 

[Lester Lugnut]

12.60V at the battery is passing if the vehicle has been at rest for 8 hrs.

But...voltage is only part of the story.

Take vehicle to a real repair shop for analysis. As previously stated, O'Reilley and other mass marketers have better equipment than most DIY types, but know little or nothing compared to an ASE cert. tech.

 

[riceandpho]

its easy to test the battery for dead cell.
meter the battery during cranking, if it dips below 11 or 10 its bad.
factory alternator should push out 13.4 on hot running. 14 on cold.

 

[duffdog]

If the charge light is not on in a Toyota, the alternator is working fine. All Toyota alternators made since 1978 are internally regulated, there is no external "voltage regulator" to break.



It sounds like you just need a new battery. If the battery has not been load tested...do that first.

 

[Twilghtzone]

Battery testers are pretty cheap on Amazon. Start at....er... $6.
Seems like you can get a pretty good one for $50 or so.