Battery voltage while driving

[Mjrodrigues916]

Hi guys, my battery voltage while driving is showing around 13.1 volts... Alternator was replaced this morning as it went out on way to work... New batteries last month. Does anybody know what could cause this? Thanks in advance.

 

[HeavyAssault]

Make sure all the grounds are good on the truck. Clean the mounting points for the alternator.

 

[Derkperk]

Are you reading voltage at the batteries with a meter or something else?


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[Mjrodrigues916]

Will check all grounds tomorrow.
Thanks

 

[Mjrodrigues916]

Using torque pro app, have not checked with DMM yet...

 

[6.0 Tech]

Ive noticed 6.0s typically dont charge at 14. Done a bunch of alternators and batteries, most seem to hover aroumd 13.1-13.3, at least on a stock alternator, imcluding the hi output stocker, but they seem to stay there no matter the load, and its more than enough to keep thr batteries charged.

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[powerlifter405]

I charge at the alternator post at 14v on a volt meter, I see 13.6 on the CTS.

 

[florida 6.0]

Same here mine always read higher at the alternator .

 

[PSD POWER007]

I’ve been curious about this too. My voltage is the same from the alternator post all the way to the fuse box power supply. But the other side of the fuse box reads lower and matches what my CTS2 reports through the OBD2 port. Usually 13.9-14.1v at the alternator/batteries and bounces from 13.1-13.8’ish on the CTS2.
On my 7.3, the readings are virtually the same throughout the system 13.9-14.1v.
On both my 6.0 and 7.3, all cables have been upgraded, new batteries, upgraded and additional grounds with clean connections.

 

[TooManyToys]

The thermistors in most alternator voltage regulators are designed to lower the voltage output from 14.4v to 13.8v as the underhood temps rise.

Part of it is the reporting by the PCM software, which varies by channel. It will never be the actual voltage, but the resistance at the positive and grounding contacts can lower it.

I've spent more time with this then a normal person should.

https://youtu.be/QYM-KD5vNWM

https://youtu.be/g3Qcgb7wAyc

https://youtu.be/LWVe_8CQPas

 

[darianmacdonald]

Great info! Thanks!

The thermistors in most alternator voltage regulators are designed to lower the voltage output from 14.4v to 13.8v as the underhood temps rise.

Part of it is the reporting by the PCM software, which varies by channel. It will never be the actual voltage, but the resistance at the positive and grounding contacts can lower it.

I've spent more time with this then a normal person should.

https://youtu.be/QYM-KD5vNWM

https://youtu.be/g3Qcgb7wAyc

https://youtu.be/LWVe_8CQPas

 

[SDER1]

What TMT said. I followed some of his grounding suggestions for my 2006 6.0L. Had a slight bump of .2 to .4 voltage increase per Scangauge II and at alternator post. Alternator was a Ford Reman OEM (110a) replaced 2011 and good to go until sold earlier this year.

 

[TooManyToys]

Thanks for the input. Glad it helped on the old truck. Enjoy the new one.

 

[Mjrodrigues916]

Thanks for all the input, tested at alternator and Batteries, all is good.