Battery/jump/electric question
 

Never had any problem till today. Had to get the car to shop, harmonic balancer replacement appointment,


and it's dead. No click, cant get out of park. I freaked out..Said 14.3 when I read gage yesterday. Said the same all year long. I jumped the car. It started but now has yellow check engine light. Got it to the shop and advised mechanic. He wasn't too concerned, said it's easy to throw a code when jumping, please educate me. During the drive there, voltage fluctuated 13.8 to 14.2
2010 ls3 base

Codes after jumping to start the car is normal and the problem codes comes really before you jump the car (from trying to start it with a low battery), since a few of modules glitch during the no start without enough voltage to the keep the alive instead. So Tech II to pull the DTC's, clear them from when you tried to start the car with a low voltage battery, and Bob's you uncle.

As for low voltage at the battery and car not starting, could be the car sitting too long not on a battery tender, battery about dead itself, or parasite draw from a module not going into sleep mode when the car was shut down. Your 13.8 to 14.2 voltage is normal when the car is running and the alternator is keeping up with the car. Hence 13.8 volt ends up when you have the A/C on or motor gets hot, both which turn the radiator fan on to star with.

Simply, if your not going to drive the car for 3 days or longer, then get a battery tender on the car. Hence car draws enough powder when the car is in sleep mode, that in about 3 weeks, it will drain the battery to the level that the car will not start. As for why we put the car on a tender when it not going to be driven for more that 3 days, the more the battery is drained down, and has to be fully charged again, the less life the battery will have.

How many amps is the car drawing when shut off, sitting in the garage. I would assume Zero.

Thanks for that, because I had the bad balancer, I did not drive it for 3 weeks. Never did that before. Extremely lucky that i had enough power to get it out of park to push it out of garage as no room for a jump. From now on I would be crazy not to back it in.

You assume wrong. These cars are notorious for dead batteries from sitting. If you have abused the battery by not keeping it fully charged all the time, you will be very lucky to have enough power to get in after a couple of weeks. This isn't a '53 Buick. All cars now days are computer driven and use a surprising amount of power when sitting. For example the BCM computer that is running continuously regularly powers up OnStar if you have it which then tries to call home.. Add to that the Corvette is a sports car and, to save weight, it uses a smaller than normal battery. THat is why you will find anyone with any time here recommending you MUST get a battery tender/maintainer if you aren't driving every day. Also, ANY discharge of a battery damages it. You can only fully discharge a few times before you need a new battery. There are people here who will say their batteries only last 2 years. My experience using a battery tender all the time is that I have gotten 7 years out of the factory battery and there is no sign the replacement isn't going to last for several more years. In the past on other cars I also get about 7 years by using a tender continuously. No waiting 3 days. EVERY DAY. If you wait 3 days you may get 5 years instead of 7 because you are doing some additional damage during those 3 days.

Ok. I bought a battery tender. Since it says no spark, must I still use positive and the grounding bolt, or can I just use pos and neg terminal?

Dumb question, now I know what the round leads were for ..duh..

Just curious...after a nice drive, battery should be fully charged, right?? I put on battery tender just after pulling in, its red, meaning its charging. Why?? Shop said batt is fine.

"They" said the battery is "fine." That doesn't tell much.

As Dano said above, if a battery is drained to one degree or another several times, it damages it permanently and it will never take a full charge again. So going for a "nice drive" may or may not help.

Any kind of test for that? Are you saying the tender may never turn green? If so, how would I know if it's working?

Tender instructions say flashing green shows 80% charge, so if red light stays on, I dont even have 80%?

Thanks, I will see if it goes green by tomorrow morn. It's been on 5 hours since I got her home.

Green light this morning. I guess I worry too much. Thanks for the education! 😀

Get the Corvette battery tender that plugs into the cigarette lighter. Makes connecting easy.


Also, all battery tenders will turn on when first connected to even a fully charged battery. They need to determine if the battery is charged or not, by monitoring the voltage to determine if the battery is accepting a charge or not.

As I've always believed, you never learn anything by doing it right the first time. :) Now you know it will always try to do some charging when you first plug it in. The time it takes to turn green depends on how discharged the battery was. I think mine takes 15 minutes to half an hour if I've just finished an 800 mile drive. As mentioned above, it takes a 20 minute drive just to get back to a full charge after just starting the car. You can still start the car after always driving just a few miles because the battery charges faster when it is farther down. So if a battery at 25% starts the car and you drive just a couple of miles, you should be back to 25% but it is going to take a lot longer to get to even 75%. Watch your voltage gauge to see what is happening.

Easy way to look at it, the tender is trying to get the battery back up to around 13.7 volts fully charged.

Hence with the tender green, pull the tender and check the voltage of the battery fully charged and should be right around 13.7 volts on a lead cell battery.

Next time you come home and before you plug in the tender, check the battery voltage at the battery terminal and will find it under the 13.7V mark, and why when you plug the tender in, it going flashing red to try to bring up the battery to 13.7 volts.


As for if you have the tender on the battery over night, and its still red, then check the voltage on the battery to see just how much you are under that 13.7V top off voltage. If your are in the sub 13 volt range, then bank that your battery has a cell or two that is going south ,or car has a nasty patisserie draw over the 1 amps that tenders charge rate that the tenders tend to work at.

As for tender hook up locations, you can do a few ways, but tend to believe that the best it connected directly to the battery terminals isntead.

Partially correct. A fully charged Lead acid battery is about 12.7 VDC.

https://cimg5.ibsrv.net/gimg/www.cor...0354dbc2e3.jpg
13.7 VDC is a float charge level which is what you might read when the Tender is connected and functioning. https://batteryuniversity.com/ has more information that anyone could every need.

I love Corvette so I am willing to put up with a very few unique issues such as high potential for dead battery when the car sits for a few days. I had a mechanic tell me the other day that a big part of battery drain in these cars are the electronics that continue to run when the car is turned off especially "on-star" monitoring. Over time your battery will drain down. There is a reason Chevy/GM offers battery protection on these cars and when my corvette is in the garage I plug it into the battery tender. Only way I know to avoid dead battery.