Voltage gauge

[BoBo_Wickersham]

New Tahoe. Voltage gauge seems to be low all the time. Thoughts?

Sent from my iPad using Tapatalk

 

[mattluttrell]

I've noticed this in mine. I wondered if the alternator disconnected when not needed to save energy. I know some Chryslers do this.

 

[jenielsen]

I too have noticed this on mine. It drops significantly lower than 14 some of the time while driving.

 

[wcourt]

Voltage gauge reading low intermittently. 2015 Tahoe. Not even 1,800 miles yet. Also, battery dead overnight. Perhaps a different issue, but at the same time, locked in 4wd with switch in 2wd. Dealer updated TCM software to resolve 4wd issue. Battery and/or voltage issue still open. Dealer still has vehicle trying to resolve. Will update later.

 

[HERD546]

I have a digital volt meter that I got from Auto Zone that plugs into the power / lighter plug. Most automotive systems run at 13.8 to 14.2 volts
The volt meter is under $20.00 it also has 3 LED's that show battery charge.
I know that there are issues with battery cables.

 

[wcourt]

Digital volt meter in the power/lighter sounds like a good diagnostic tool. I will get one. Dealer still has the Tahoe (day 3). This is an update today from the dealer: "We know there is definitely an issue it’s just a matter of getting the concern to happen and then diagnosing what we duplicate".

 

[wcourt]

Well, I have the Tahoe back from the dealer (after 5 days). They say it is "highly likely" the voltage problem was due to the old TCM software. Because it was stuck in 4wd and they did update the software, they have not had a voltage drop issue. Time will tell. I will say that since the software update, the steering takes more effort at low speed. I guess I will assume that's normal until someone tells me otherwise.

 

[Mad Maxx]

I know it's an old thread, but rather than make a new one....

I noticed my Voltage Gauge is reading low like a few people in here. Has anyone found out if there is an actual problem, or if this is normal? Measured Voltage at the battery at Idle, and it was 12.62

 

[ccapehartusarmyINF.(ret)]

whoa yeah thats a no go hooah
on a newer vehicle yer alternator should be crankin out 14.4 volts with out breakin a sweat
12.6 volts at the battery at idle hell i dont even think thats enough to charge the battery
what voltage are you getting at the alternator the little terminal on the back

 

[t.stimpson]

from what I understand on my 09 yukon the alternator is "as needed" so my voltmeter shows different settings anwhere between 12-14. I'm guessing this might be the same with the newer trucks?

 

[Mad Maxx]

I'll check Voltage at the Alternator tomorrow or Monday. I have the truck on my CTEK tonight to charge.

To me, the Voltage is Low, I've been in the Aftermarket Industry for over 15 Years, and 12v Electronics is one of my main fields.

But...on these "New Vehicles", you just don't know what's "Normal" anymore. I know if I take it to the Dealer, they'll tell me it's within spec and send me out the door.

 

[08grey]

It's normal. If your battery was taking a charge at 14.4 volts all day and night it wouldn't last as long as they do. If you want to test it plug in something with a high amp draw. If it's a 15 it should have a ac DC converter. Plug in a fan. Turn it on low then med then high. You should be able to see the voltage regulator kick in and start charging the battery.

 

[Mad Maxx]

It's normal. If your battery was taking a charge at 14.4 volts all day and night it wouldn't last as long as they do. If you want to test it plug in something with a high amp draw. If it's a 15 it should have a ac DC converter. Plug in a fan. Turn it on low then med then high. You should be able to see the voltage regulator kick in and start charging the battery.

I'll keep an eye on it the next few days. This could just be another thing to add to the list before I send it to GM telling them they NEED to buy this thing back from me and give me a New / Different one.

 

[wcourt]

OK, Here is the deal. I could not find anything on the low voltage/charging issue nor could the dealer provide any useful information so I requested information from GM. The following is their reply:

The Electrical Power Management Overview (as they call it) The electrical power management system is designed to monitor and control the charging system and send diagnostic messages to alert the driver of possible problems with the battery and generator. This electrical power management system primarily utilizes existing on-board computer capability to maximize the effectiveness of the generator, to manage the load, improve battery state-of-charge and life, and minimize the system's impact on fuel economy.

Three functions are:

It monitors the battery voltage and estimates the battery condition.
It takes corrective actions by boosting idle speeds, and adjusting the regulated voltage.
It performs diagnostics and driver notification.

Charging system operation. The purpose of the charging system is to maintain the battery charge and vehicle loads. The engine control module (ECM) controls the generator output. The normal duty cycle is between 5 - 95%. The output of the generator is contingent on the on the duty cycle, e.g., 20% duty cycle yields 11.56 volts, 50% - 13.25 volts, 80% - 14.94 volts, etc.

The GM document is too long to post in this forum (please reference GM document ID: 2206057)

Bottom line is the lower volt meter charging is normal.

Good luck.

 

[angelmom05]

I know this is an old post, but I read the entire document you referred to here. My 2017 Chev Tahoe is doing the same thing. So I guess it’s normal?

 

[dbbd1]

I know this is an old post, but I read the entire document you referred to here. My 2017 Chev Tahoe is doing the same thing. So I guess it’s normal?

Yep!

 

[RED TAHOE LS]

Voltage gauge, $3.53 free shipping on ebay, plug in power/lighter. Had one for 3 yrs, perfect.
David g...........