I've had my 2014 1LT Coupe (Cyber Gray Metallic) for 3&1/2 years now, and the voltmeter has always been pretty consistent. It will read around 14.6 v until the surface charge wears off. Then it will eventually settle to about 12.8 v after a few miles of driving. Today I went out for a drive, and, after starting, the voltage dropped down to 12.4 v almost immediately and stayed there for several miles. Then, it eventually climbed back to its normal level of 12.8v. Does anyone have thoughts as to what would cause this? My only thought is that it could have something to do with the extreme heat we have been having. I do still have the original battery. I would appreciate any opinions on this. Thanks.

 

Have the battery tested. May be an early sign of failure.

 

Could be the heat, thinking your battery is reacting to higher operating temperatures. It will be interesting to observe voltages when the ambient temperature returns to eighty degrees.

 

Has yours always read below 13v when running?

Mine has always been 14-14.5v.

Our '14s are getting up there, so it's not surprising to see our batteries starting to lose their oomph!

 

Are you talking about the voltage while the engine is running or the voltage across the battery terminals when stopped? It is normal for the car to vary the charge rate, down to about 12.4v, unlike the old systems that charged at a constant voltage. If you are measuring the battery voltage without the engine running and it is only 12.4v, the battery is nearing end of life and it is time to consider replacing. I already replaced the battery on my 2014, and was surprised it was only a 30 month battery. I replaced it with a ACDelco professional Gold series battery with a 42 month free replacement warranty. A fresh battery should have over 13v.

 

The voltage will vary a lot when driving and a system reading in the low 12 volt range while the engine is operating can be entirely normal. The alternator output is controlled via its field winding to provide the desired current output and it may be reduced for a number of reasons one of which is to improve fuel economy under some driving conditions. I haven't looked in detail at the logic of the C7 system but charge rate (which is a function of applied voltage) is probably being reduced during high ambient temperatures to improve battery life. Sealed batteries aren't truly sealed, they still have to vent excess pressure, and a high charge rate at high temperature can cause venting with resultant loss of liquid electrolyte and shortened life. Higher current loads (think electric fan running at high speed in hot weather) will also drop system voltage.

As long as the voltage does come up to a reasonable charge rate at times the alternator and charging logic control is likely fine. Checking battery voltage under load is the best determinant of remaining battery life.

The operating voltage level in modern vehicles varies a lot more than it used to in the old days when simple internal or external regulators were used to control alternator output but with the new smart controls built into the ECM alternator current output, and thus system voltage, will vary widely to meet different conditions. It isn't as noticeable in the C7 and other vehicles with HID or LED headlights but with simpler halogen and other incandescent headlights it can be quite annoying at night. My 2002 Olds Aurora was annoying at night because it had an early version of this "smart" alternator logic and transitions in voltage were sharp enough to cause very noticeable rapid changes in headlight output.

I had never paid much attention to the voltage display (separate selectable readout) in my 2008 CTS but I checked it shortly before leaving for a long trip. Because I saw it varying a lot I decided to replace my 4 year old battery before leaving the next day because it was varying quite radically from a low in the low 12 volt range to near 15 volts at times. I installed a new battery and it behaved exactly the same (as intended by the system) so the battery I replaced was probably fine.

 

Did you buy your replacement from a GM dealer or another source? Do you mind posting your source and cost? Thanks.

 

As usual, NCS5, has delivered a very informative post, with which I completely agree. My battery is now at least 36 months old and behaving very normally w/ charges varying between 12.6 and 14.5, which I consistently monitor with the summary display available in DIC Tour mode.

I'll offer a few other observations. A 30-month battery doesn't mean it's only going to last that long, and is more of a minimum expected lifetime even when abused. It could easily go twice that or more if well-maintained, which means not allowing it to discharge too deeply, too often, or better yet, never.

Constant short trips of a few miles at a time are also big battery killers. They get depleted and the alternator never has enough time to keep them topped off.

Given how so many Corvettes seem to sit over long periods, without being driven, keeping a battery maintainer on it can significantly extend battery life. The alternative is to use it as a daily driver with real miles put on it.

 

Down here in the Florida Inferno, batteries are toasted and usually don't last long. My OEM battery died when the car was 2 years old with a dead cell. 2 volts across the terminals. I seem to recall similar behavior like you described before it died, but it kept on going for a few months.

There are MANY options now for exact fit batteries. Search is your friend when you want to research them. I went with a AGM from Advanced Auto as it was on sale at the time, but they are also sold at Sears, Auto Zone and elsewhere now. Exact fit, even down to the vent, except they come with a built in handle! No more PITA removing the battery! More CCA than the Delco and cheaper. I believe they are all made by the same company and they slap different labels on them.

 

My '05 C6 still had the original battery when I sold it after 6 1/2 years. It was always on a battery tender when not in use. I hope to continue to do the same with my '14 C7's battery and it's been good so far after 3 years 9 months. Opps, now I've done it!

 

 

Such a variation usually occurs from a failing voltage regulator. Not sure if the Vette uses a standard regulator integrated into the alternator but a common failure is low voltage when subject to elevated temperatures. I have had experience with two of my cars and that of friends where this had occurred. All were left in service anyway with no ill effect.

 

When you start getting odd electrical issues its time to replace that battery before it goes out on you and leaves you stranded. My 14 battery went out at two years. They are warranted for 3 years fyi.

 

My 2014 gave me one symptom, it gave a slow crank after a 30 minute drive. I stopped the car for a show and needed to restart it to move around a little in the show area. It gave a very slow restart. It barely managed to start the car. After the show, it started just fine. I replaced it the next day (2 months ago) with a Diehard.

Model 50748, size G48
Specs Compared to OEM:
CCA @ 0F: DieHard = 760; OEM = 565
20hr Ah: DieHard = 70; OEM = 70

Weight DieHard = 44 lbs; OEM ~40 lbs

Perfect fit and exact replacement.


Elmer

 

FWIW, this is a 9 page pic/text PDF of my install of a AGM battery in my 2014 C7 last summer. There are a few tricks so you don't crack the back or rip the unbound carpet when you access the battery. (Posts of dealer ripping the carpet! Good chance if you wait and ask an AAA person to jump when the battery fails, they will cause a carpet tear!)) Also how to deal with the large power board on the positive terminal. Need to be sure the replacement battery fits the power board, especially if you want an AGM as I did.

http://netwelding.com/Battery_Issues.pdf

 

I just bought my battery from a local auto parts store that carries ACDelco batteries and parts.
The battery actually lists for $216, but I paid $138.

When I said that I was surprised my Corvette only had a 30 month battery, I know batteries can last longer than the warranty, I just meant that I was surprised that GM put the ACDelco "silver" series battery in instead of the ACDelco "Gold" series.

If you get the 42 month free replacement series, you should never have to buy another battery again... I have taken batteries in that are over 3 years old, told them that it is not holding a charge as well as it used to, and they gave me a new one with no other questions.

I replaced my 2014 battery when it was 3 years old... It was still starting the car alright, but my experience has been that after about 3 years, the battery could go at any time. Less trouble to replace it at my convenience rather than after it has failed. I let my 2011 Camaro battery go 5 years, but I don't depend on that car as much.

As JerryU points out, getting the battery out without tearing the carpet, etc. can be challenging, so better if it is planned.
I ended up removing the hatch side panel so I could more easily fold the carpet back without it tearing. I also removed the fuse box wiring to get it totally out of the way since the battery is difficult to get out of the well even when everything is clear.
Be sure and remove the vent tube, or it will hang up when you try to pull the battery out. The other end is secured to the floor of the battery compartment.

This photo shows where all the clips are located..

 

....of heat AND age....I brought my 2014 into my mechanic (Mark at Titus-Will in Olympia, WA...he's terrific) to have a new exhaust system installed and when I saw what a pain in the **** putting in a new battery was, I bought/brought a new Delco and let Mark do in 15 minutes what would have taken me an hour, a sore back and some choice vocabulary to do (PS was always an Optima yellow top guy but it won't fit now).