my c5 battery goes dead in two weeks if i don't drive it ,is it the battery or something else?

 

do you leave the key in the ignition when you park it?

 

nope the keys are out and everything is off

 

Should I not leave my key in the ignition?

 

https://www.corvetteforum.com/forums...rage-draw.html

 

Even if you do track down the excessive drain and correct it,you should use a quality tender such as the Ctek.The C5 is notorious for being finicky about voltage levels.First thing i did when i got mine was order a Ctek 3300 and if the car is sitting it is hooked up.A good AGM battery with the highest RC also helps.Torque your battery terminals.

 

Aside from looking for a current draw, it might be easier and faster to get a load test on your battery. If you do, you need to charge the battery fully first. These cars are tough on batteries, especially when they sit for a week or more. I've had great luck with the Optima red top. I had one last fifteen years, I used it in two different C5's. There will probably be forum members that will disagree with me on Optimas.

 

follow 8vette7's advice. But I've used Battery Tender Plus's on all of my equipment for years - you can't beat them. If my Vette is going to be sitting for any longer than a week, it's on one. Cheap insurance.

 

So does mine - I keep it on the tender if I know I'm not going to run it for more than a week...

 

Agree with others here...if you are going to let it set, hook up your Battery Tender (or similar smart charger).

 

Glad to see this thread is still alive. I have a few questions about the continual drain of my Red Top Optima Battery in my 04 Vert. I am not
technical at all, so any test such as those suggested with using an altimeter would have to be "paid for" at my local mechanic of choice.

A little background followed by a few questions, please ....

1) my battery has been tested by two different places and both say the battery checks out just fine. After charging it will stay at 13 volts as long as I am driving the car a little bit every day, so I suspect that my Alternator is working just fine.

2) I have tightened down the terminals so that they are snug and do not move.

3) After about 5 days of not driving, like this morning, the battery voltage is between 5.7 and 6 volts. Wow. To me that's a significant
drain, but I've looked at what I can and there doesn't appear to be any lights remaining on as I inspect my car carefully in the dark garage.

4) One small thing, I have one of those 6" seat belt extenders which make fastening the seat belt so much easier, and I leave the extension in place all of the time. I don't think this would cause a drain, but wanted to see what you guys thought. After all, all it does is add 6" with a similar "female" fastener on the end just like the one that is
original. Don't see why there would be any power drain here.

5) If I did take my car to a mechanic to check for the source of a power drain, any idea how much I should be charged for this w/o
being ripped off. I wish I could do this stuff myself, but simply am
no good at such stuff.

Thanks so much for everyone's patience and help with this. I can't
stand having to charge up my battery almost every time now when we get a nice sunny day around here and I want to take my wonderful car out for a spin.

 

Although the Optima battery will still be drained from sitting just like any other battery. The modern Corvette; C5-C7, have monitoring going on even when the car isn't running. That will cause the battery to go down within a few weeks. Drive the car as often as you can. It will keep the battery hot. Might have the alternator checked just to see that it's charging the battery when running.

 

The extender on the seat belt IS NOT an issue. I can explain why if anyone wants to know.

You have some kind of an issue. Load test the battery FIRST.

Next place your hand on all the relays in the engine and passenger foot well and see if any feel warm or hot.

Also try exercising all the seat and door switches. Common for a switch stick or fail and cause a drain.

I will post my DIY on finding drains when I get home.

PS: DO NOT charge a dead battery in the car without removing the negative cable. It could damage electronics. I can explain why if you want to know.

Doing the drain test is something I could teach you how to do. Very simple and you could learn a lot. Also, it would be free except for buying a multimeter and that would be less than half an hour of shop time.


Mr. Sam

 

Thanks for all your help Mr. Sam. So frustrating to have to now deal with this. Let me ask you something else. When I do turn the key and my car won't start I do hear the motor back where the antenna is located clicking for a few seconds, could this be a source of the drain and if so, how would I check this specifically? A fuse?

 

 

OK:
Any place like AutoZone can load test your battery

The relays are large squares looking devices in the fuse boxes and even listed in your Owners Manual along with the number and purpose like the fuses

Don't doubt a switch can be an issue. Unlike cars of years ago, much of the C5 has power on the circuits at ALL times. It is very common for seat switches to stick and a motor runs until the breaker trips, cools sown, close and the motor runs again until the battery is dead.

Technically a battery is dead at 12.1 volts but charging at that level is OK. I would never do it without disconnecting the negative cable in the C5 if it was 10 volts or less for sure.

Here is my DIY:

Here is some info for determining if you have a parasitic drain. Let me know if I need to clarify anything of if I can help in any way.

Suggest you remove the hood light bulb first so it does not provide a drain.

For measuring battery drain I would hook up an ammeter to the negative side of the battery by removing the negative cable and measure between the cable and the negative battery post.

When you connect the ammeter the car should draw several amps until it goes into "sleep" mode which can take several minutes. Normal sleep mode drain should be 30 milliamps or less by GM standards. You will need an ammeter that can transition from whatever the drain is down into the sleep mode. If you have a drain I suggest the following:

Once you determine you have a drain with an ammeter what I recommend first is to listen to each fuse box and see if you hear any relays operating. If not, then place your hand on each relay to see if any of them feel hot. That can be the start if you find something like that is happening.

If nothing shows up you can hear or feel then I recommend you separate the two fuse boxes from each other. This is easy and done by removing the Red cable from the engine fuse box that feeds the passenger fuse box. It is on the right rear side of the engine fuse box. There is a stud there where the large Red wire from the battery connects. Just remove the nut and disconnect the large Red wire feeding the passenger fuse box and reattach the Red battery cable. NOTE: I would recommend disconnecting the negative ammeter hookup when working on the positive side doing this.

What you will be doing is measuring the drain with an ammeter to see if disconnecting the passenger fuse box causes the drain to go away or not. By depowering the passenger fuse box you will depower the BCM which controls the sleep mode so do not expect the sleep mode to happen.

If removing the feed to the passenger fuse box you then see you have eliminated the drain then you know it is something related to those circuits. If it does not reduce the drain then you know it is related to the engine fuse box. It could be a rare case where you have some drain via both fuse boxes and we can deal with that if you think it is the case.

Just so you know, even though it may appear to be a problem in the engine or interior area the fuse boxes do feed circuits to each other that are not affected by separating the boxes. So, separating the fuses boxes can tell you how to narrow down your search but still not where the issue may be. That is where the schematics come into play to track down the “real” culprit. Hope that makes sense.

Once you basically know where it is then you can remove fuses and relays to see where the drain is coming from.

PS: There are cases where the alternator causes a drain so it can be disconnected and see if the drain drops.


Mr. Sam

 

I do the same thing and also use a Battery Tender Plus. Works great and no worries about a weak battery (unless the battery itself is bad).

 

I'm going to file Mr. Sam's instructions for when I'm in the same boat. Very helpful and easy to follow and understand. Anyone that would take the time at 3:45 in the morning to post this is a good guy in my book.

 

Sam and Chuck are Good guys at any time and in any time zone

 

I was told I was good for nothing. I DISAGREE.

I can always serve as a BAD example.


Mr. Sam