No courtesy light timer on mine.  It is possible the interior lights were on all night, but it's unlikely.  It's parked in our garage right now where I see it all the time at night versus my shop where it usually lives.  But possible.  Doesn't take much for a door switch to fail and go to ground which turns on the lights.  Alternator is definitely a possibility too.  It's a reman that I bet is more than 10 years old.  Or the alarm relay.  Or something else.  Or it could just be the battery with no drain.  I'll be looking into it later this week.  Thanks for the suggestions.  



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Dave, I had a '77 in the shop years ago that had a battery drain issue that eventually turned out to be the courtesy light switch on the passenger side. Had a hard time finding it because the car only had ONE interior light that worked to begin with. Turns out someone had replaced the switch with the wrong one(too short), and it was keeping the light circuit on all the time. Sometimes a door left partially open with a so-so switch will do the same thing.
I'd still start with having the battery tested, then the alternator, and then go from there.

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

For anyone that is interested, here is a pretty decent article on Testing for parasitic battery drains...


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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

My parasitic drain turned out to be my center glove box light.  The lid wasn't pushing the plunger far enough.  I discovered that on a dark winter afternoon.  I could see light coming out around the edges of the lid.  Did a bubba fix on it and all is good.  Also have a disconnect of the battery itself.

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Winter! In Texas! In May? Musta been a DARK nite, or a BRIGHT lite. 😈😀 LOL!

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Click on image for full view

Well, sunset probably isn't as early as your's but it's darker a 5pm in November than it is now. 

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If the battery was drawn down to 2 volts then there was a drain of some sort.... however, if it charges up to 11.5 volts then there is a cell that has gone bad.  Each cell provides about 2.2 volts .  Costco batteries are usually the heaviest batteries that Interstate carries. Though I don't advocate using the heaviest battery available, at least in our cars(C3's) the battery is not located in the engine compartment, so heat is not a factor in the life of these batteries.  I have seen Costco bad batteries in the pile that were not very old.  As the boss usually says about some of our batteries "Two pounds of 'stuff' in a one pound bag".   Otherwords, the higher output batteries have more plates in them to obtain higher cranking amps, which is ok given that its not in the engine compartment, otherwise the heat from the engine would severely shorten the life of the battery. 

have the battery checked then go from there to find a drain.... :)

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StingrayJim
NCM Lifetime Member #1936

Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94

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Thanks everyone, but after some checking today I don't think there's a drain.  Or if there is, it's intermittent.  

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Thanks for the additional info, Jim.  That 2 volts may have been wrong, but I'm not sure.  My voltmeter may have been acting up.  It did definitely come up to full charge, though.  When I was exchanging it, Costco asked if it was a "bad cell" and I did just say yes.  So is there something about that battery that would not work well with our cars?  It's a group 78, CCA 800, CA at 32 degrees is 1000.  

|UPDATED|5/23/2016 6:21:41 AM (AZT)|/UPDATED|


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i went through 3 battery is three years.  Each died almost to the day a year later.  Always a bad cell.  All through Advance Auto/ Western Auto.  Last battery I got has now lasted, knock on wood, 7 years.  All were high quality, so I thought High dollar batteries.  Found out there was a manufacturing flaw according to the sales guy that they were replacing a large number of batteries.  They tried charging me for the prorated deal but managed to persuade them not to

My drain turned out to be the alternator.  Posssibly a blown diode allowing reverse current flow.