I don't drive my vette too often -- once or twice a week when the weather is good and maybe not for two weeks or more if the weather is bad, as it can be this time of year (although it has been great this winter so far and I've driven it a lot lately).

The battery tends to gradually discharge during long periods between drives. About two weeks ago the thing had been parkedfor quite a number of rainy days, etc., and it almost did not start. I think this is a common problem with C5s and C6s - I know of two other owners who have had this happen. I think it is all the on-board electronics that gradually draw it down - even when the car is off some of them are one. I know my Porsche has that problem and the owner's manual mentions it particularly - about ten days and -- no start.

Attached pictures show a "battery tender" I picked up at Advanced Auto from something around $25, which I mounted to the wall in my garage. I's rather small and not designed to provide much of a charge - maximum 1.5 amp, but it has a "float" function where it shuts off if the battery is fully charged (that way you don't over charge it, which can be bad for lifetime). It took the jumper-cable type clamps off and soldered on the male connector from locking type power connector plug made for short-wave radios, etc., that I bought at radio shack for $8 or so. I cut an appropriate sized hold for the female part of this connector in the lower trunk well (the battery in my vette is in the trunk well -- I used the Lingenfelter kit -- I would have done it anyway but with the extra 50 lbs for the SC up front it really helps to move a roughly 50 lb battery to the trunk, and its down lower in the car, too). Anyway, I wired that in permanently to the batter terminals.

How all it do upon getting home from a drive is snap the charger's cable into the fitting in the underside of the trunk well, and it keeps the battery completely topped up. That way, during Jan and Feb when there are weeks at a time i won't be able to drive it, it will stay nicely charged up.



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I have an 2003 zo6 with what appears to be a fairly new Optima battery. Nobody punched the dates on top so I'm not really sure how old it is. I bought the car about 6 weeks ago and haven't driven it for the last two. Got in it last night and dead battery. Left it on a trickle charger, (Battery Tender I use on my motorcycles, 1.25amp) and nothing this morning, 5.84Volts. Is it time for a new battery or will an Optima Charge back up?

Thanks

 

I imagine you need a new battery, but before doing that why not beg or borrow a real battery charger (50 amp) and try to fill it up fast?

Consider this: Depending on the model, your Optima stores something between 550 and 850 amp-hours. Split it down the middle and call it 700 as an estimate: assuming the battery was truly dead (i.e., completely "empty" as it might be after sitting for a while) it would take a 1.25 amp charger 560 hours (three weeks and two days) to fill it up to 700 amp hours - and of course it would take much longer, since as I say in my post here and as is discussed elsewhere, these cars typically draw about 1/2 amp just sitting, so . . . you are actually making a net contribution of only about .75 amp per hour -- come back in 6 weeks!

You have nothing to lose by putting it on a real charger at about 50 amps -- realize that 15 minutes on a 50 ampcharger is more power input than it got overnight with the trickle charger. I'd put it on one and see if it starts after two hnours, if not, after four hours, and if not anything then, I'd begin to assume its gone bad.

You might also want to do like I did and keep the thing on a trickle charger when its idle for a while. Like I said, they do this routinely.

 

Thanks Lee

 

Lee -I had the same problem - didn't drive the car enough to keep the battery charged. I went ahead and spent the bucks for the Deltran battery tender plus. It's a little more than others, but the thing I liked was that you can buy the optional cigarette lighter adapter and run the charger through it. Makes it real convenient.

 

Hey, I have a 2000 SS Camaro, and I'm the same way, if it rains, car doesn't move. So mine will almost go dead, also, even though it's in a heated shop, i only keep the thermostat on 45-50 (natural gas is extremely high) so the floor still stays very cold and if i leave it for about 2 weeks, the tires will get flat spots in them, to keep the battery charged, and help the engine, I'll go down, crack the roll up door, and turn the exhaust fan on, and crank my baby up and let it run till it completely warms up, and that seems to keep the battery charged pretty well. Still doesn't solve my flat spots. I'm going to be upgrading to a 'vette soon, and since it's the same engine, and low-profile tires, I was wanting to know if cranking it up really does help the battery or if it's my imagination. Also, got a solution for the flat spots, because I'm not going to drive it around the block and there snow on the ground, sorry, don't like cleaning the undercarraige that much.

Thanks for the info(even though this thread is about batteries and not tires),
Jonathan