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Inconsistant Voltage Readings Charging System


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My volt meter often varies from less than 14v to more than 14v. Not able to duplicate on demand. As you can see in the picture, it's not dropping below 14v because its at idle, that is driving down the highway in the day time heat on med/low, wipers off, rear defrost off, no trailer, no plow. At other times it is past the 14v mark by about the same distance it is below in the picture.  I want to know if this is a problem, or how it operates by design.  I'm oldschool, to me anything less than 14v charging, off idle indicates a problem.  Anyone else notice this?

low volts.jpg

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One of the computers manages the alternator based on a long list of things that the truck monitors. 

It will also change the engine idle speed if it decides it is necessary base on state of charge and loads.

 

Not a simple voltage regulator that was used in the past. 

 

 

There are pages more info but:

 

Electrical Power Management Overview
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.

 

The electrical power management system performs 3 functions:
• 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.

The battery condition is estimated during ignition-off and during ignition-on. During ignition-off the state-of charge of the battery is determined by measuring the open-circuit voltage. The state-of-charge
is a function of the acid concentration and the internal resistance of the battery, and is estimated by reading the battery open circuit voltage when the battery has been at rest for several hours.

Edited by redwngr
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3 hours ago, It's Tim said:

What?

That your driving on fumes @ 56 mph  playing with a camera?

cute.

Yeah I was in a hurry to get to the gas station, while also testing to see if the fuel pumps have been improved in the last 15yrs. LOL

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33 minutes ago, redwngr said:

One of the computers manages the alternator based on a long list of things that the truck monitors. 

It will also change the engine idle speed if it decides it is necessary base on state of charge and loads.

 

Not a simple voltage regulator that was used in the past. 

 

 

There are pages more info but:

 

Electrical Power Management Overview
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.

 

The electrical power management system performs 3 functions:
• 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.

The battery condition is estimated during ignition-off and during ignition-on. During ignition-off the state-of charge of the battery is determined by measuring the open-circuit voltage. The state-of-charge
is a function of the acid concentration and the internal resistance of the battery, and is estimated by reading the battery open circuit voltage when the battery has been at rest for several hours.

Interesting. Guess they don't make em like they used to! What ever happened to a simple voltage regulator? So much more that can fail and hard to diag without proper scan tool I would imagine. But technology is not always a bad thing either.

Edited by Rail Boss
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