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Here's a nice easy to read diagram to use in tracing your drain. Save it to your computer and you can zoom in if necessary. If you have a/c, let me know and I'll attach the same diagram with a/c added.
With a fully charged battery, just disconnect the large red wire from the back of your alternator and check the battery in the morning. If you can wait 2 days you won't even need a multimeter because if the diodes are bad in your alternator, the battery will be drained.
With a fully charged battery, just disconnect the large red wire from the back of your alternator and check the battery in the morning. If you can wait 2 days you won't even need a multimeter because if the diodes are bad in your alternator, the battery will be drained.
Just to be clear, if you disconnect the large red wire, the battery will NOT be drained if the diodes are your problem. If connected and the battery does drain, disconnected it does not, the diodes are the problem
AS instructed I put an ammeter in series between the + post on the battery and to the cable (disconnected) that goes on that post. I only drew 9.7 ma.
So does that mean the new battery itself is bad?
Could it still be that if/when the clock gets stuck it drains the battery?
Yes. I had the clock contacts stick closed twice on me. All other times (days/months) everything was fine. In both cases, although I had a battery disconnect, I was charging the battery and simply left the disconnect in service (although battery can be charged either way).
I was using a Battery Tender with about 1-1/2 amp output. The clock contacts sticking pulled about 4 amps. 4-(1-1/2) = 2-1/2 amps discharge, which was enough overnight to pull down the battery a significant amount. I only discovered it since the BT was running HOT from trying to win against the clock.
FWIW.
Suggest you do some troubleshooting with the ammeter. Disconnect meter. Turn things off and on a few times and activate different electrical circuits. Then reconnect the meter and check the readings again. May need to do for a few days to finally find the problem. Or just DISCONNECT THE CLOCK LEAD for awhile.
If you have your decimal in the right place, that's excellent. Make sure it is .0097 (9.7ma) that you're getting. It's possible the battery just isn't holding a charge, I'd check the drain a couple more times, maybe after a drive and see if it repeats. If it drains sitting in the garage, pull the bottom fuse and see if it still drains. If it does not, it's in the glove box light staying on sometimes or the clock. If it does, pull the red wire off the alternator and see what happens. If it's actually 9.7ma, it won't drain the battery. My 65 could sit for 2 or 3 weeks and still fire right up, sometimes it was even longer in winter time between drives. I did have a quartz clock movement.
Last edited by 65GGvert; Jun 19, 2016 at 05:44 PM.
The battery has held a charge all day off the charger. The clock has continued to work.
When I took the battery connector off of the battery post I did notice that there were visible wires at the end of it; I covered that with electrical tape; does anyone think that could have been causing the leak/drain?
The battery has held a charge all day off the charger. The clock has continued to work.
When I took the battery connector off of the battery post I did notice that there were visible wires at the end of it; I covered that with electrical tape; does anyone think that could have been causing the leak/drain?
I also am new to the whole corvette thing as i recently purchased my first 1965/396. My car seems to be having the same type issues so i appreciate all of the input your thread received.
little more old tech. disconnect negative battery cable and hook 12v test light across. If lit means drain. disconnect alt, fuses, etc. until light goes out or dims to find culprit.
I also am new to the whole corvette thing as i recently purchased my first 1965/396. My car seems to be having the same type issues so i appreciate all of the input your thread received.
GOOD LUCK
Welcome! It would be best to start your own thread as this one is old - you'll get more responses that way.
little more old tech. disconnect negative battery cable and hook 12v test light across. If lit means drain. disconnect alt, fuses, etc. until light goes out or dims to find culprit.
This^^^^. It's the simplest and quickest way of finding a current draw big enough to drain your battery.
To R Smith,
Could not find your new thread, but I had the same problem in my '65 convertible years ago. The cause was a milliamp draw through the power window switches. When it would rain, a bit of water would trickle down into the little bathtub below the switches and cause a small current draw from the battery. Over a few days the battery would be dead!
Solution? Drill a couple of 1/8" holes in the corners of the "bathtub". Problem went away and has not recurred.
Don't rule out the alternator yet. Wait until you get your ammeter (external multimeter, not in dash ammeter for those reading that into it), and if you have too much draw, disconnect the red wire to the alternator and see what happens. Checking the charge can show good and still have a backward short (very small drain is possible) in the diodes. Get that meter and start with measuring amount of drain. Post back what you get if you like and I will try to help you through the steps if you want me to.
A good possibility . Have seen this happen several times. Alternator will charge battery but when ignition is turned off will drain battery .diodes In alternator is faulty.
OK thanks; would not have known that reading thought the owners manual, thats for sure!
The clock movement on R66 is worn out and stops every couple of minutes unless it is laying on it's face. Fooled with it for a few days before realizing I was the fool.
I unplugged the connector on the back of the clock and turned it 180 degrees to connect only the ground to the clock case. The rest of the console lamps get their ground thru the clock. Make sure you do not connect the 12v+ supply back to the ground lug or you should blow the fuse.
I set the clock to 5 O'Clock and we are now both happy, as is the owner of the PUB.
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But I'm and old mechanic. 
