My 08 is mostly a garage queen, but every now and then it does need to come out. Recently I've wanted to get it out, but I seem to have a dead battery, and I don't know why.

Despite being hooked up to a Battery Tender, over the winter the factory battery kicked the bucket. I attributed this to a bad Battery Tender, as one of the lights had gone out and I figured it had issues (which seems fairly commonplace). I replaced the battery with an Optima Red Top, replaced the Battery Tender with a CTEK 3300, and all was well during the summer.

A month or so ago I wanted to wash the car, so I went to pull it out of the garage. It barely turned over, like the battery was very weak. It started though and all seemed fine.

Two weeks ago I wanted to get it out, but it wouldn't turn over. All the lights in the dash and interior put on a light show, but there wasn't enough juice to do anything else. I paged through the menus to get to the voltage and saw that it was 8.5. Not good.

So I put the CTEK back on and let it go for a little bit, maybe an hour. It didn't start, which I expected, but the voltage was up to 9. Thought that was a good sign, so I hooked up the CTEK again and let it go. The next day the CTEK said all was well and tried to start again... but again somewhere between 8.5 and 9 volts.

Just to remove some variables I disconnected the battery and hooked the CTEK directly to it. Let it go for a week or so, during most of which the CTEK said it was fully charged.

Just came in from trying it out. Disconnected the CTEK, put a multimeter on the battery, it read 13.something. Reconnected the battery, got in, and tried to start it. Still absolutely nothing, and now the dash said it was 8.2 volts. Put the multimeter on the battery again, it said 10.something.

So do I just have a dud battery or what? Had no problems with it until this stretch. Nothing was on in the car that should have drained the battery to an unhealthy level - though I have one of the remotes to control the NPP exhaust, I always leave it in the open position to eliminate/minimize drain, plus it was on the CTEK the whole time. I'm hoping it is the battery - if not, what might it be?

 

Take the battery and have it load tested. That will tell you if the battery is good, without a load you really have no idea. Wouldn't be the first time a new battery failed. If the battery does check good, get it charged and start the car, look what the system voltages are, should be around 14.5 volts.

 

It's the battery.

The voltage level that counts is the one you measure under load. You may read 12V on a high-impedance multimeter, but that number will collapse once the ignition system is drawing current.

And the computers will brown-out before the starter otherwise would, which is how Corvettes with marginal batteries fail to start one day but fire right up the next.

Sounds like you need a new battery. As for why it got discharged in the first place, I could only guess. Could the CTEK have gotten switched off by accident?

 

There's no doubt battery is shot. Get a new one. I also don't have an answer what happened, but I would charge the battery every week or two, and disconnect the charger. Even though they're designed to be left connected constantly, I don't trust them. Besides, the Optima being an AGM, requires less voltage. If you fully charge it with a regular charger, it shouldn't be an issue. But left constantly, maybe that's what fried it. I'd buy an OEM if you're going to use a normal charger like a BT+ or CTEK 3300. They're quite cheaper than an Optima. I used to buy Optimas, and never had good luck with them, especially in the engine compartment (heat dries them out eventually). Good luck.

 

I agree with ELP_JC. Ditch the Optima. I've never liked them either. Get an AC Delco or a Die Hard/Interstate battery and charge it for a good 12 hours before putting it in the car.

 

A new battery shouldn't need charged, your car will top it off. Take it for a drive, 1/2 hour or more should do it. That is a good time to check your voltage regulator on the DIC.

 

The stock battery in my 08 dumped on a Sunday a couple of months ago. I had planned on buying a new replacement Delco but the store was closed on Sundays and I needed to have a battery in the car before Monday morning so paid about $50 more for an AutoZone Duralast battery. Threw the new battery fresh from the store into the car and it fired as soon as I touched the switch. Hope the Duralast lasts as long as the Delco.

Bill

 

I have an old 6 amp/12volt Craftsman battery charger and I like to charge even a new battery when possible before installing in the car. You dont know how long it sat on a shelf at the store before you get it.

 

I replaced my battery on my 05 in 2010 with an optima red.

I also purchased a Deltran battery tender, recommended by a friend who has used several units on his Vettes and Camaros full time.

For the past two years I will charge my Vette about every month for about a day, because I drive on the average 1 per month. Remember the car is always on, representing a constant load presented by at least by the Ecu, waiting to be driven.

 

It doesn't need to be charged to fire up the engine, but you substantially lengthen the life of the battery if you fully charge it BEFORE you ever crank the engine. I know this is not going to happen if it craps out in the middle of a trip. But if you have the chance, fully charge it before installing it. I ALWAYS do that, especially on motorcycle batteries. And no, the car never fully charges a battery; it only 'bulk' charges it. Only a charger will get it fully charged. And you want a trickle charger for that, not a fast (high-amp) charger, like many motorcycle dealers use.

 

Replaced my battery a few months ago after 6.5 years of use from the OEM Delco. Before I fired up the car on the new battery I made sure it was properly watered and then put it on my Battery Tender+ overnight. It was fully charged then before use. I continue to keep it on the tender whenever it's in the garage, which I did with the old Delco.

 

I have to eat my words. I purchased a new Delco last weekend and the battery isn't performing properly yet. I think the garage had it on the shelf awile and it was not fully charged, should of charged it. I just had it on a trip yesterday, over an hour leg each way. I placed it on the battery tender and it is still red, not fully charged. We'll see what happens, with my luck I got a defective battery.

 

Update, my battery is now fully charged. This morning the battery tender green light is on indicating the battery is fully charged and the tender is in float. It took over ten hours to reach this condition after driving a 3 hr trip, 1 1/2 hr each leg. This is the first time I had a new battery give me trouble, the first time I replaced a battery in a car (C6) with systems operated by a multitude of voltage sensitive computers. I had all kinds of interesting problems after the car sat all week even though I drove the car 1/2 hr after installing battery; no FOB detected, car would not turn accessories off when I stopped engine and exited car (was all screwed up) then would not start until FOB inserted in glove box FOB location. Seems the alternator charges battery a lot slower than I would imagine?? I expected a high amperage charge rate that evidently doesn't occur.

 

The question is: Has the new, fully charged Delco solved your original problem?

 

I am not sure all is well. The battery operated the car normally after I installed it, though probably not fully charged. Sitting all week with one short test run, the car had issues on the next start attempt. After having the battery tender on it for a few hours, everything was normal on my road trip. Upon returning home after a 1.3 hr leg 3 hr total drive, the battery still needed 10/12 hours on the tender to reach a fully charged condition. It is currently on the tender, green lighted. I will use the car probably tomorrow on a typical short trip, see what happens after I let it sit a few days without the tender after the short trip. I could let it sit three weeks without the tender before the car needed a new battery, and it would start without any issues.

 

It seems like most battery tenders put a little more charge into the battery than the alternator does, and that takes some time. Others have commented about this. Our 2009, both with the original battery and the replacement Delco, takes several hours (maybe overnight, I never checked) for the tender to show fully charged.

 

Today removed the tender to run a few errands and test the car. To my dismay the drivers door hesitated to open (red light door locked indication) finally did open after after a few seconds. I pushed the start button, no FOB detected on the DIC, like "WHAT" is going on, the battery is charged and new battery in FOB? I removed the FOB from my coat pocket and the car started right up, performed normally all three starts later. On the way to the bank it hit me. I got an IPhone this summer, untill now never had it close to FOB, today it was virtually in the same pocket, removed FOB away from IPnone, car operated normally. Did I replace battery because of interference? Well, it was 6 1/2 years old anyway. The car is going to sit a few days without the tender, see what happens on the next start.

 

IPHONE can definitely interfere with the fob as well as other electronic devices.

 

Ready for an unexpected update? I didn't yet get around to figuring out the return process for the battery, so it remained hooked up to the CTEK since my original post. During that time I noticed that it stayed orange for a few days, instead of fairly quickly going green. I figured the battery finally gave up and the charger couldn't do much with it.

Just to be sure, I just went out and tried to start it. It started without any problems, with the voltage from 14.4 to 14.6 as it idled.

So now do I trust it enough to take it out for the emissions testing due this month (then park it until spring and see what happens then), or do I try to return the battery that now probably won't show any problems?

 

Sounds like your battery finally took a charge. I would talk to your battery retailer and see what their policy is on something like this. If the battery is charged use it. I don't park my car over winter. Due to road conditions my winter trips usually are local back roads to and from the soft ice cream store.