We have a 2014 C4S Cab with about 10K miles. On recent road trip SC to FL observed the following. Outside Temp around started around 44 and ended around 60 F. Oil has around 5K miles on it (changed last April)

At constant 80 MPH in 7th gear PDK:

With Sport button depressed water temp: 194 Oil Temp 196-206 battery Voltage 15.1-14.1 Crept down 2-3hours into drive

With Sport button not depressed: Water temp 194 Oil temp: 226 battery voltage 13.6-13.8 Down shifting seems to not effect Oil temp by more than a few degrees

As best i can figure the dynamic Motor Mounts require the higher voltage

As RPM was same in either mode why the different oil temp? I am guessing but can't see the spoiler that it may extend further in sport mode? Suggestions? Should i be concerned?

 

In sport mode car is less worried about efficiency and runs the oil cooler in preparation to run it harder. Normal behavior.

 

You are good. Just like mine.

 

As a rule on a 991 or any car for that matter I wouldn't get worked up about any gauge value that is within normal limits.. and I wouldn't get hung up on specific values associated with specific modes of operation.

With regard to battery voltage.. don't get wrapped around the axle on specific values. And note it would be incorrect to say something using power in the car requires "higher voltage".. In reality everything on a battery bus operates from whatever voltage is present. However depending on the load required it may be required to supply a higher electrical current..

That said the battery voltage can vary for a couple of reasons. If for example the car isn't running (i.e. no alternator charging) typically the battery voltage will be instantaneously reduced depending on the total load. So turn on something that has a high current draw and the battery voltage may drop a little. This is an inherent characteristic of batteries and is related to their internal source impedance. This is just basic electricity and electrical engineering fundamentals.

When the engine is running the battery voltage can vary all over the place depending on the electrical loading, the battery charge state and engine RPM. Car Lead Acid Batteries are charged by applying a voltage higher than their nominal cell voltage. The actual instantaneous charging voltage may affected by many variables (including temperature) and may not be obviously predictable or repeatable.

The actual electrical current is much more important than Battery Voltage, but unfortunately that is rarely displayed. Battery voltage is just a secondary indication of what is happening in the electrical system, and doesn't tell you the entire story.

Moral of the story, don't worry about battery voltage.. The only way it will be too low or high is if there is a charging system failure. If that happens you are going to get some other kind of fault reported..

 

^ look at the brains on Brad :-)