I got a 2016 Z06/7 2 weeks ago. When I opened the garage door on the 3rd day, the battery was completely dead. No power to anything. It is certainly possible I left something on from the night before, but I just don’t know what that could have been. I called a pro to jump it, but that didn’t work. I then read that if might be better to charge it slowly. I set up a charger and in 3 hours the car started. There has been no issues with starting since.

Thinking there might be something wrong with the battery, I took it to the dealer who was very helpful and tested the battery. According to their test, the battery was still in “Good” condition.

However, would like your experience here. In the mornings, it takes longer to start. It’s turning over rapidly but takes longer than when the car is warm. Additionally, this morning I connected the Corvette battery tender and it reads 1/2 charged and then a full charge in a couple hours.

Questions…
Is it normal to take longer to start the car from a cold start?
Is it normal for a "good" battery to to read 1/2 charge on the battery tender?
Assuming I didn’t leave something on, what would cause it to be completely dead the next morning?
Should I be thinking about replacing the battery soon?

Thanks for the advice!

 

The typical car battery does not do well with a full discharge. This alone has done a good amount of damage to the battery.

All modern cars leave many electrical components running even though they appear to shut down.

I would get a new battery at this point. It is not worth being concerned you will run out of battery power to start the vehicle when you are well away from home.

While I find treated well modern batteries last a good six to seven years, many here would replace the battery by age alone given you have a 2016.

 

First, I would check the connections to make sure it is tight. If this was the case, you wouldn't be the first to be caught by this.

Yes it does take longer to crank before start up when cold.
Can't answer the tender question, because I don't use one (someone else will answer shortly).
The Car should time out and go to sleep ~ ten minutes after exiting.
Your battery is getting long in the tooth, so this could come into play with all of the above.

 

Buy a Duracell gold 5 year battery.

 

If its a 16 AND the original battery it is due for replacement. Most corvette batteries that are starting to fail will start displaying some odd electrical messages on the dash or doing odd things with electrical components. Replace the battery and be happy. Oh, and replace your fob batteries while you are at it.

 

Check the MFG date on the info label on the driver door. Your 2016 could be 4 1/2 years old by now, including the battery. I changed mine out last July at 3 1/2 and was having no problem. Also did same with the fob. Corvettes are power hogs and will not tolerate a weak or declining battery. You are not doing anything wrong. Continue using the tender even with a new battery.

 

Or they will just die and give no warning. No way to predict. But 4+ years is pushing it, IMO.

 

If the battery is the original one, very possible that it is time to make a change.

 

Replace battery.

 

Generally speaking, a battery that goes from being able to start the car to being completely dead (as in completely discharged) indicates that something created a parasitic load that drained the battery. The fact that charging the battery brought it back to life and has since tested OK supports this. If the battery was bad it would not take a charge and work normally. As posted above by Elk, a complete discharge is quite harmful to the battery. I would replace it based on this alone. Battery life varies a lot by use and what its state of charge is normally kept at. My 2014 has its original battery and works fine. I contribute that to using a tender so the SOC is always full. By the way, the indicator on the Vette's tender either indicates "half" or "full". You can't use this to determine the charge. It shows the "half" indicator at all times until the battery is no longer taking any charge, at this point is simply indicates "full".

Your car must have an intermittent fault that puts a parasitic load on the battery and drains it. All the lights and accessories in the C7 time out - I don't think you can leave anything on even if you tried to, though somebody here might know otherwise...regardless, if it happens again you will have to have the car tested for what is causing the drain. Perhaps before buying a new battery and subjecting it to another flatline event you might consider letting this car sit for the same three days and see if the problem reoccurs. No sense compromising a brand new battery with a few flatline events.

 

I disagree. I went down the path of something else is wrong with the car because the battery "passes" the test, and the test failed to identify a problematic battery EVERY time. That includes batteries that were not at the end of their warranty life. The test does not identify batteries that are unable to hold a full charge over a short time period, only those that have an internal failure fail the test.
Years ago I bought into the something else was wrong theory and poured a bunch of money into a car believing the battery test to be correct. Finally, I replaced that battery in that car and learned all the dollars I spent were wasted, it was the battery. Since then I've had numerous instances where a battery went from starts the car fine to completely dead in a short period of time including in 2018 year with our 2014 Lexus. In more than one instance, the battery went from starts the car fine to dead on the same day. Batteries do not follow one protocol before dying. Sometimes they warn us with a slow start, sometimes they don't.
OP replace the battery. It's the least expensive corrective action to take.

 

I'm not sure what it's worth here but I don't know of any battery tenders that can take a 70 Amp-Hour battery from 1/2 to full charge in a couple hours. That's 35 Amp-hour/2 hours = 17.5 amp charge rate. A battery charger maybe, but a tender?

 

A few other things to consider: first, it's a '16--do you know/did the dealer say it's an original-to-the-car battery? If it is, it could be going on 5 years old. Plus, per most posts on battery life, heat is the killer meaning outside temp. You're in Dallas--not Arizona, but not Missouri either. So those hot, long summers could be a battery life-shortener, too. Finally, even if it's a newer battery meaning bought within the last two-three years, you probably have no idea how it was taken care of, meaning, if the car sat for long periods without a tender and just ran down to where it would start, but weakly, this would sap the longer life of it as well.

Roadbike below makes a good case, and I've experienced what he has for many years with other cars---not every car, but enough to know that when it comes to batteries, anything can happen. Including the fact that a brand new Corvette, with a factory battery went stone-dead in the third month with 3 weeks of non-use and no battery tender on it. Jump start, used battery tender from then on most of time when not in use for a week, etc. and instead of needing to be replaced, it lasted at least four more years when I replaced it just to be sure.

I also don't think you charged a battery with a tender, but a quick charger in a couple hours to get a dead battery to start. That can be both bad and good to the battery IMO.

 

AORoads - you are correct. I should have been more clear. I recharged the dead battery with a charger (Boost mode) and have started maintaining it with a tender.

Thanks to everyone for the advice. It is the OEM battery. I'm going for peace of mind and getting the battery replaced. This is really a great group! I've missed it! Good to be back.

 

^^^
Good idea. As others have said. once dead it will never be as good! A lead acid battery is NOT like a cell phone Li-ion battery, it does NOT like being fully discharged. I changed mine at ~ 3 1/2 years and put in a AGM (Absorbed Glass Mat) battery. I bought one on sale, more capacity than OEM.

Here is a PDF I made on How To Change- save some money: http://netwelding.com/Battery_Issues.pdf

 

One of the other possibilities could have been a bad alternator/voltage regulator. Even an on again, off again connection. Being a '16, it probably doesn't have enough miles on it to be the alternator. But anything is possible. Wonder if you got your alternator's health checked?

Good to hear a new battery fixed the problem.

 

OP, I see you’re replacing battery & that’s a great idea. You said car is new to you so I want to point something out I didn’t see in other posts. If you hold the start button in for 5-8 seconds (without foot on the brake) to play with electronics, you will enter the diagnostic mode which does not “time out” & keeps the car ON till start button is pushed again to bring it back to accessory mode which does time out/goes off when door is opened also. Diagnostic Mode is so service techs can hop in & out of the car while running tests & opening/closing door without car electronics shutting down in middle of tests. 👍

 

And I think this is exactly what I did that ran the battery down! I had put the car in diagnostic mode to tweak the settings and didn't go back to accessory mode. Thank you for posting this!

 

I bought my '17 new from the dealer lot in December 17. According to the "born on" door sticker date the car was 15 months old when I bought it. About six months later (just short of two years battery life) the battery showed signs of going south and was replaced. I doubt the dealer had a "battery maintenance procedure" for cars on the lot and batteries sitting unused are slowly dying.

 

Something that hasn't been mentioned. In the mornings it will take a few more cranks than when its warm to start because the high pressure fuel system has bled down and needs to come up to pressure. So its not necessarily how fast it starts but how fast it turns over until it finally starts. That would be a metric on battery condition.