2017 GMC Sierra battery drainage while driving

[Loodie]

Recently replaced the original battery after it refused to charge. After replacing it with a brand new battery I have been noticing the battery gauge drop from 14v to roughly 12.5 after driving and running the truck for around 30 minutes. Truck is all stock except for battery at 32k miles. Nothing has been messed with except the replacement battery. Is this common to see that voltage drop on the gauge and just didn’t notice until I have been more cautious since the dead battery or is there some things I should look into?

 

I checked continuity to all the terminals connected to the positive side and everything is passing enough to beep the multimeter. Is there a possible fuse problem (if so do you know where it is?) among a possibly bad alternator? If you have any information it would be much appreciated. Thanks, Lance.

[JimCost2014]

3 minutes ago, Loodie said:

Recently replaced the original battery after it refused to charge. After replacing it with a brand new battery I have been noticing the battery gauge drop from 14v to roughly 12.5 after driving and running the truck for around 30 minutes. Truck is all stock except for battery at 32k miles. Nothing has been messed with except the replacement battery. Is this common to see that voltage drop on the gauge and just didn’t notice until I have been more cautious since the dead battery or is there some things I should look into?

 

I checked continuity to all the terminals connected to the positive side and everything is passing enough to beep the multimeter. Is there a possible fuse problem (if so do you know where it is?) among a possibly bad alternator? If you have any information it would be much appreciated. Thanks, Lance.

Welcome to the site.

 

Normal, 

Battery Load Management The vehicle has Electric Power Management (EPM), which estimates the battery's temperature and state of charge. It then adjusts the voltage for best performance and extended life of the battery. When the battery's state of charge is low, the voltage is raised slightly to quickly bring the charge back up. When the state of charge is high, the voltage is lowered slightly to prevent overcharging. The voltmeter gauge or the voltage display on the Driver Information Center (DIC), if equipped, may show the voltage moving up or down. This is normal. If there is a problem, an alert will be displayed. The battery can be discharged at idle if the electrical loads are very high. This is true for all vehicles. This is because the generator (alternator) may not be spinning fast enough at idle to produce all the power that is needed for very high electrical loads. A high electrical load occurs when several of the following are on, such as: headlamps, high beams, fog lamps, rear window defogger, climate control fan at high speed, heated seats, engine cooling fans, trailer loads, and loads plugged into accessory power outlets. EPM works to prevent excessive discharge of the battery. It does this by balancing the generator's output and the vehicle's electrical needs. It can increase engine idle speed to generate more power, whenever needed. It can temporarily reduce the power demands of some accessories. Normally, these actions occur in steps or levels, without being noticeable. In rare cases at the highest levels of corrective action, this action may be noticeable to the driver. If so, a DIC message might be displayed and it is recommended that the driver reduce the electrical loads as much as possible. See Battery Voltage and Charging Messages 0 155. Battery Power Protection This feature shuts off the dome and reading lamps, if they are left on for more than 10 minutes after the ignition is turned off. The cargo lamp shuts off after 20 minutes. This prevents the battery from running down.

[Loodie]

Thank you JimCost2014! I was hoping it was normal and appreciate the very informative and insanely fast response.

[JimCost2014]

9 minutes ago, Loodie said:

Thank you JimCost2014! I was hoping it was normal and appreciate the very informative and insanely fast response.

You are very welcome.

 

Straight from the Owners Manual. 

[Thebeak]

I have a 2018 Sierra All Terrain 35000 miles on my 3rd battery since November they are changing the memory seat module,we will see if it works.

 

 

[Texmex1982]

I have a 2015 GMC Serria Denali and it was having similar issues both battery cables were bad.

[2018GMC]

Voltage changing while driving is normal as stated by others. If you have starting issues or odd messages on screen after starting (service stabillitrack, low battery, service restraint system) Check the resistance in the battery cables. I had my dealer do this before warranty was up and my negative cable tested bad (high resistance). They replaced that and no more random messages after startup.
https://static.nhtsa.gov/odi/tsbs/2019/MC-10168185-9999.pdf