A new curiosity seeker here. I also have a 2014 Impala 2LT. This antique mind of mine it having one heck of a time wrapping itself around all the all this new info. Give me good old 57 chevy charging system any day. I too have been researching the Impala charging system. For a week or so I noticed 11.8V on the DIC engine off. Verifed reading with a multimeter. At high way speed DIC displayed 15.3V. Thinking bad battery, off to the dealer. They ran a battery analysis--batt OK. While performing the analysis they put a top charge on the batt. Turned the key on and read 12.7V. Pulled on the hyway DIC read 14.8V 25 miles to home. After ingine was off 2 hours rechecked batt with meter 12.7V. Cold night, 0 degrees but in garage no heat batt read 12.7v w/meter. Took of driving DIC reads continuous 15.3v. At idle 14.8V. Is all this info acceptable? 57 Chev I like you would like Tech2 provide us access to his info source.

 

Additional info. Impala has been siting for 2 hr. Batt volt 12.4. Start up DIC 14.8v at idle. After 20 sec shut off motor, turned key on, 13.2v. 15 sec with key on all else including running lites off batt dropped to 12.1v. key off reading meter 12.2v. I'm confused. Do I have to put a charge on the batt now to get it back to top chg?

 

You are worrying too much. This is why they turned off the volt meter in the DIC.

57chevythunder should be providing a follow up.

There is a whole section in the Helm's service manual related.

 

Your probably right Sledge. I , like 57 Chev thunder, am retired. I like a real brain teaser and I think this charging system pretty well falls in that category. I'll probably chase my tail on this till I figure it out or crash. I will see if I can that info in the Helm's Service Manual. By the way, nice looking ride.

 

I have been curious about this issue also. I usually see 14.7 or so (sometimes slightly higher or lower) after starting, and for quite a long time (20 mins) with temperature in 20s. It then might or might not go down to say, 14.2 v. Today it was only 4 degrees, voltage stayed at 15.1 or .2 the whole 40 minute drive. So as suspected, it seems to have much to do with what termperatures are, but I am a bit surprised it is so high. I have looked at it before starting the engine, and it shows only 12.0!! Summers are warm here, so it will probably be lower then. I have owned it for about 15 months now (2104, with V6), haven't usually paid a lot of attention to voltage, but have only seen it at 12.x something only one time, it was warm then.

 

Placed a battery maintainer on the batt overnite. This morning removed the maintainer. After half hour, with multimeter, battery read 13.2V. Opened the car door for 10 sec then closed door. Batt reading dropped to 12V. Started car and read charge volt at 15.3V but never brings batt back to 12.6v. Charge volt remains at 15.3v continuously as long as I am driving it. Only way I can return to 12.6v is with the maintainer. How can that be normal?

 

Okay guys, I guess its time to post another reply.
First, a quick reply to Rookie#1, "welcome to the discussion." Yes, I hear you regarding the simplicity of older battery charging systems. (gosh, I cut my teeth on mid-50's chevys, with their old DC generators and electro-mechanical voltage regulators,,,which usually kind of sort of worked until they broke, or wore out.) -then I worked in the trade for a while in the 60's and 70's. Although GM could never legally admit it, when they "copied" the basic alternator in about 1963, calling it the "Delcotron Generator" (-which may still be their label) they finally joined the technology and reliability of that time period.

Afterward the basic Delcotron charging system remained pretty much the same from the 70's through probably at least the early 2000's, with minor improvements along the way. -from my experience they were pretty danged understandable and reliable.

HOWEVER, now somewhere around about 2005?? they really dove into the deep end of the pool !

I will have to admit that I have spent a ridiculous number of hours over many days, trying to find some good detailed descriptions of "what the heck is going on today!!!" And let me say in no uncertain terms, IT IS A COMPLEX SON-OF-A-GUN nowadays.

First with all due credit to "tech2" in post number4 of this thread, we would do well to go back and re-read that post. From my perspective that data there has the exact right numbers. Also post number 5 of the following link is really worth reading because it does a pretty good job of describing the six "modes" of operation. -even though it is for a 2009 GMC, the basics are the same and the descriptions are close enough. Voltage gauge question 2010 Sierra 5.3 - 1999-2006 & 2007-2013 Chevrolet Silverado & GMC Sierra 1500 - GM-Trucks.com
I did FINALLY get a copy of a the GM document titled "Charging System Description and Operation" that is specific to our 2014/2015 Impalas. It is a whopping fives pages long, and I have not yet figured out how to share that document, -or even if I can legally.

But once again, let me re-state that the numbers for those six modes given by "tech2" is exactly what is contained in the 5-page document I have. And the above link to the 2009 GMC document has the same descriptions of each mode, essentially word for word.

I have written my own one-page summary, which I'll be glad to post in another reply. Also I have a lot more comments on this topic, including battery maintenance devices, GM's term "80% state of charge", and others that I will be more than happy to share, but had better get off this current already lengthy reply.

-til later, 57chevythunder.

 

Great info 57 ChevyThunder. Read it all and printed it out. I feel I'm close to understanding the theory behind it all. Now I'm moving on to the battery, specific gravity versa voltage. When all is said and done, I'll go after schematic diagrams of the system. Thanks for all the good info. Decide to share the five pages, let me know.

 

Okay guys, I finally have my "full book report" ready. (just joking,,, sort of,,,) -actually I've titled it "My GM Charging System Review" and will see if I can successfully attach it to this reply.

I certainly hope everyone who wishes to read a whole lot of details will enjoy it. Others may fall asleep well before completing it !!

And above all else, PLEASE realize that my review is only my personal findings on the subject, and should be treated as only my opinion. It is certainly in no way to be treated as an official technical document of any type.

Again, THANKS to everyone on this forum who has been very helpful in trying to get the whole thing of "unexpected" battery voltage readings figured out. (if nothing else, maybe I will eventually convince myself that "all is well" and I need not worry.)

Enjoy !!

footnote: well the file attachment idea isn't working yet. -first the "docx" wasn't a recognized file type, and when I convert it to "doc" it is too large.
I may just try to send it in pieces as separate replies.

 

Okay, here I go again in attempt to attach my charging system review document. Hope this helps everyone that has been puzzled by our "strange" number.