My baby has been asleep for 18 months with a Battery Tender being it's battery baby sitter. Green light on all this time. Car started fine and I backed it out into the driveway and shut it off. Half hour later the car would not start and I had to boost to get it going. Volt meter on dash showed battery voltage around 11 volts. Ran engine for 15 minutes and battery now was fine. I called Deltran, the makers of the battery tender, and they told me that my charger is not powerful enough to handle new car's parasitic battery draw and I should upgrade from 0.75 amps to 1.25 amps. According to the techies at Deltran the smaller charger is OK for a '57 Chevy, but not for new cars because of parasitic draw. My understanding is when a Corvette is parked it goes to "sleep" and there is minimal current draw. I don't want to disconnect my battery to put a meter on it because the car will "wake up" and I won't get a true sleep reading plus my clock has started working again and I do not want to disturb that. Has anyone got any ideas whether or not my 2007 C6 will be drawing over 0.75 amps while being stored?
Question Parasitic battery draw
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I know our C6s have quite the parasitic draw but never knew how much. Mine sits on the CTEK all winter that came with it and I have not had an issue yet (touch wood). Even my earlier Camaro used to sit on the maintainer with no problem. But admittedly it probably had less parasitic draw.
One thing you can try is a measuring the current draw from the maintainer to your battery. If it stays pegged at 0.75A all the time with no change then I think you might have your answer. There should be some variations over time as the maintainer adjusts itself. You have me curious now and when I get back home later this summer I will have a check on mine to see what it is doing.
One thing you can try is a measuring the current draw from the maintainer to your battery. If it stays pegged at 0.75A all the time with no change then I think you might have your answer. There should be some variations over time as the maintainer adjusts itself. You have me curious now and when I get back home later this summer I will have a check on mine to see what it is doing.
The green light should not have been on if the Tender wasn't keeping up. If your car started fine after 18 months, it would appear the tender was doing it's job. A half hour later and being discharged, would indicate to me that the battery is toast. JMO
I agree with Rruuff Day. Just because you had a battery tender on it doesn't mean a battery can't finally die from old age. I keep a battery tender junior on mine and all has been well on a new battery for 2 winters of 7 months each. A battery tender should work fine for a C6 Vette. A trickle charger is not needed or wanted if your system is fine. I'd start with the basics and replace the battery.
Thanks guys. I guess I will have to do a battery test to see if it is toast. My third car, 2002 Mustang convertible, was on separate battery tender this winter when the light went to red and the battery tested bad. Replaced battery and car spent next 5 months sitting and all was good, green light and all. No more problems there. Sort of proves Rruuff Day's comments on the 'Vette.
I’d check the condition of the battery first. How old is the battery? Get AMA to check the battery (free).
I agree with RRuuff. If it started the first time, it's not the tender. If your gauge was only showing 11 volts, you've got a problem - that should be up over 13 if your battery isn't fused and your alternator is working. My guess is a dry cell or two in your battery. Also check your terminals for security and cleanliness - a bad connection is all it takes to do really weird things.
I experienced this this spring afte having my tender on my battery for 3 weeks, to top it up started 1 time then wouldnt start again, tender said a ok, inspected battery and all 6 cells were empty of liquid lol, new battery is awesomesauce.
My original battery in my 2014 finally died last winter. I replaced it with a red top Optima battery. Lots of CCA but it isn't a factory replacement, so I'm wondering if the new battery is better than an oem one? Thoughts??
Normal parasitic draw on a C6 is 0.02 amps, once everything shuts off.
I had a yellow top Optima that went bad after only 6 months. I have a Battery Tender Plus, and if the battery has a bad cell, the tender may still get to a full green, but will not hold charge for long once separated from it.
As mentioned, it is either bad connections or a bad cell on the battery.
I had a yellow top Optima that went bad after only 6 months. I have a Battery Tender Plus, and if the battery has a bad cell, the tender may still get to a full green, but will not hold charge for long once separated from it.
As mentioned, it is either bad connections or a bad cell on the battery.
I should have posted what happened after that bad day Put car back in garage after boosted when battery appeared dead and ran engine for about 20 minutes until voltage meter constant at 13 volts.. Couple of days later car started normally, drove outside and parked where it would be easy to boost. Shut off. No more problems - drives and starts fine - never changed battery. just one of those crazy gremlins and not the American Motors kind.
I've found that these newer cars want a strong new bettery. Buy the highest cold cranking amp battery that you can get and even then they become iffy after about 4-5 years. A couple of years ago, I replaced the Delco battery with a $300 Delco and it didn't last but about 9 months. Checked out at the dealership, the battery was no good and I got a new one under the battery warranty. It has worked fine since then. I always use a battery tender if the car is going to be sitting for any length of time.
Battery care makes a huge difference in battery life in my experience. My ATV still has the original battery after 13 years and it still works like new... Tractor battery is 10 years old... ditto... 8 year old Lincoln battery ditto... 22 year old diesel truck batteries were replace 10 years ago with Costco Kirklands... No problems with them either. I have battery tenders or solar maintainers on everything except my daily driver.
Wow!!!
I saw that once. You can charge any dead batteries. It must really work. If that’s the case its worth paying for the procedure. 
Your batteries will service you longer if you never let them go dead. Especially in our climate here in frigid AB.Wow!!!
I would still test the battery to be sure as it might be on the edge. Assuming your battery tender is working correctly, it should be fine for maintaining and would only have trouble charging due to the low amps. You've been driving with it fine, so it's probably fine, but if you have a regular battery charger it wouldn't be a bad idea to charge with the charger and then only use the maintainer for maintenance. If you want to check for parasitic draw, it takes about 20 mins for the BCM to turn off and the car to go to sleep and it draws about 4A at first. It's possible the battery could have be on the edge, it gets undercharged (charger could have been in maintenance mode so not actually charging), starting draws some more down, sitting the BCM is drawing steady, the battery hasn't recovered and then it doesn't start. It's a stretch but just thinking of ideas.
