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2017 Grand Sport with a new OEM Battery
I did a 40 mile run just now, mild temperature in the mid 70’s. The new battery was installed about a month ago. I had the display in touring mode that shows the list of various temperatures, tire pressure and battery voltage. The battery voltage was consistent from start to end of drive at 14.7 volts. I did see it change to 14.6 volts for a couple of seconds. The car is not on a tender as I use it about 3 to 4 times a week. I am curious as to what others are seeing for battery voltage on the center display. I guess I would have thought it would be more in the 13 volt range.
I would expect the charging voltage to start near 15 volts and drop down to around 13 volts as the battery became fully charged.
There is a current sensor on the negative battery cable as well as a small black wire on the negative battery cable clamp. Both of these need to be intact for correct battery charging operation. They are easy to break when changing the battery.
If either of those two wires are broken you will get a charging system error. Those wires are remote sensing wires for the alternator. They provide battery voltage feedback that is used by the alternator to vary it's output voltage to maintain a close to optimal charging voltage at the battery terminals. That means the alternator voltage level shown on the Instrument Panel will swing more due to changing system loads to make sure the voltage at the battery remains constant. Older systems only regulated the system voltage seen at the alternator output terminals, not at the battery.
I have seen my alternator voltage go from close to 16 volts, down to 12.8 and back to 14 while driving. The longer I drive the closer it stays to 12.8 volts with intermittent voltage spikes.
I will check the small black wire in the morning with more light available. The red is on correctly. I had checked it before. I put a trickle charger on overnight to get it topped off. Could be I may not be driving enough to keep it fully charged.
There are no charging system faults indicated on the dash display.
If every C7 owner just used a smart battery maintainer every time they do not drive their vehicle 90% of reported battery issues on the forum would vanish.
You should see the charging voltage start to drop after a few minutes. Since you just got a new battery, it can't hurt to double check that the battery cable clamps are pushed all the way down, flat, and tight. There have been a few cases of cable clamps not fully engaged causing issues.
Of course there is a chance that you got a bad battery off the shelf. Not likely, but it does happen.
Just checked the wiring. Small black wire OK. Red and black large cables tight. I also noticed that after 5 hours of trickle charging, the solid green led came on indicating that the battery is fully charged.
Yes, now in hindsight, a trickle charger would be a good idea since I do not have many places to go recently. I do have a trickle charger on my house generator, jetski and the boat battery banks. The Vette may be getting used as few as 2 trips a week and some are only 5 or 6 miles.
I will start it up in the morning and note the voltage with the battery charged. Guess using a trickle charger creeped up on me.
Battery measured 12.74 volts with a digital voltmeter after starting engine and shutting it down.
Last edited by radar314; Jan 16, 2021 at 09:44 AM.
Reason: Update imfo
Success!
Like I mentioned, I did the trickle charger overnite and it showed fully charged. Put the top down and went for a drive. The voltmeter on the dash indicated 14.8 Vdc. After a couple of miles, it started ticking down, 14.6, 14.5 and kept going. After a couple more miles, 13.0, 12.9 and then it stopped at 12.8 Vdc and held there. ( I had checked the charged voltage this morning and it was 12.74 Vdc) Stayed at 12.8 Vdc for the remained of the ride.
I think I have decreased my driving so much since last March, there has just been a constant downward trend on the battery. Over the past months the gauge shows 14.x all the time because I was never getting the battery fully charged. The lesson here, to me, is to use the trickle charger more often and keep the battery topped off and not allow the constant depletion state. Hopefully this will help someone else avoid this problem.
Battery Voltmeter Reading
