My battery drains in one hour. I disconnected the negitive cable and pulled every fuse, when I put a meter between the negative post and the cable it was pulling 12.8. Could the positve cable be grounded? Car starts on a full charge

 

Bad battery. If it does it with neg cable disconnected.

edit- after rereading your post I might have misunderstood.
You need to retest and put your meter on amps setting. This will tell you if you have a draw.( I use a test light in place of the meter. )

 

Could it be a bad diode in the alternator? Pull the big red wire off the alternator and test again and see if the drain is gone.

 

I will take the battery in and have it tested. I put a low voltage test light between the post and the cable and it blows the light every time.

 

Having your battery tested is the best place to start.

It isn't obvious to me what you're testing and how you're doing it. If your battery takes enough of a charge to start the car but is still running out in an hour, I'd suspect a serious power drain. There are some pretty good test procedures out there for isolating these. I'd suggest starting at corvettefaq.com

 

I will and thanks. What I was doing was trying to find out why the battery would drain. It was suggested that I should remove the negative cable from the post, be sure everything is off and put a low voltage test light between the post and the disconected cable. If it was bright there was drain. Remove fuses one by one until the light went out. I removed all of the fuses and when I put the test light between the post and the disconnected cable it blew so I put a voltage meeter between the two and it was drawing 12.78 volts. I think the positve cable could be grounding out but I would think that would cause the car not to start.

 

I get it now. By "low voltage" i hope you mean 12 Volt. If you are using a 12 Volt light and are frying it with this method, you do indeed have a significant drain somewhere. Almost too much of a drain for any of the circuits that are protected by fuses. I'd suggest following the positive cable looking for a place where it is touching the frame.

Start at the starter motor and look for smoke.

 

With that much voltage, I would say either alternator, as mentioned earlier, or starter/ignition switch. Do you have any additional accessories added to your vehicle?

 

I will trace the cable.
No addtional accessories added.
So you think it is worth the time to test the battery?

 

Check between the disconnected neg cable and the neg battery post with an ammeter.. See if there is a spark when disconnecting the cable.
I just had to change batteries in my 97 camaro. It would start and run fine, then restart when warm. Let it sit overnight it wouldnt start, jump it it would start and run and restart warm. When I went to check the battery I noticed the date on the sticker on top was 1997.
PS: I bought a new AC Delco battery to replace that 13 year old AC Delco battery.

 

I did and it was 12.7. and yes it did spark when I disconnected it.

 

Did you make sure that all the lights (hood, dome, underdash) were out before you checked this? Those lights will also cause the cable to spark on the battery while removing the cable

 

I pulled all of the fuses to be sure

 

Some points to make your troubleshooting easier. Your battery/electrical system DOES NOT "draw" 12 volts. Voltage is a measure of POTENTIAL. If you go to Auto Zone and test their on-the-shelf batteries with your voltmeter they will (should) also show 12 volts.

Your problem is CURRENT drain. Current is measured in AMPS. To determine the current drain you need an ammeter.

YOUR MULTIMETER MOST LIKELY HAS AN "AMPS" SETTING BUT YOUR METER IS MOST LIKELY NOT DESIGNED FOR THE LEVEL OF CURRENT FLOW YOU ARE EXPERIENCING. THE HIGH CURRENT MAY DESTROY YOUR AMMETER JUST LIKE IT BURNED OUT YOUR LIGHT BULB TESTER.

Current (amps) equals Voltage divided by resistance (ohms). Your fuses are designed to blow out at certain amperage levels to protect the electrical circuits in your car.

POWER (watts) is calculated by multiplying Voltage times Current (amps).

The rapid battery drain could be a "dead short" i.e. your positive cable directly contacting a ground (e.g. frame). You did not indicate any fuses were blown. The rapid battery drain you are experiencing would blow out smaller amp fuses which would indicate the problem is most likely NOT equipment protected by these smaller fuses.

For example: if you left your car door open for an hour (Courtesy Lights ON) it WOULD NOT completely drain your battery.









http://science.howstuffworks.com/question501.htm

 

Think of electricity as water flowing through a hose. The pounds per square inch pushing it is the "voltage" or pressure. The amount of water or gallons per minute flowing out the hose end is the amperage or flow. For your battery to drain in one hour, you have quite a bit of flow going on. The outer covering on the positive cable may have rubbed through to the wire or another power feed (before the fuse box) is touching ground.

 

Wow , I don't think I've ever seen that happen. I would imagine if you could get the starter to engage through the bulb it would blow it.
I'm surprised with that much amperage draw that the fusible links are still intact.
A battery test won't hurt but the battery is not causing the draw or short.

In a quite garage when touching the neg battery cable to the neg batt terminal can you here any clicking or signs of anything happening ?
Like others have said disconnect the alt and retest.
If the pos battery cable was grounding you should see some smoke or sparks or fire.

 

Just noticed you have a 68. The wiper bypass in the 68 has been know to create a large draw and if by some chance you put the 14 black "ground" wire for the wiper and heater motor on the pos term of the solenoid you could create a big power draw.
Do you remember what wires are on the large lug of the solenoid with the large pos battery cable ?

 

I wouldn't test for a large power draw inside my garage - might burn the car and house to sh*t.
I also think you may have an intermittant internal battery short.

 

An "internal short" inside the battery wouldn't cause his test light to 'blow' when checking for a power drain. He has a very high current draw in his system. I would start looking at the condition of the positive main line from the battery (to the starter area). If the cable has rubbed through and is touching the frame [or some other piece of grounded metal], that would cause such a condition.

If your volt/ohmmeter has the capability of measuring "AMPS" (10 amps or higher is best), you can substitute that meter for the test light. BUT YOU DO NOT WANT TO FIX IT IN THE CIRCUIT...you want to connect one of the probes but only touch the other to see what reading you will get. If it jumps off the scale quickly, remove the lead immediately so that you don't damage the meter. Such a result would tell you that the current drain is much higher than 10 amps and you probably have a serious short in your system. If it draws less than the full scale capability of the meter, then you can leave it connected and start pulling fuses until the drain goes away. That fuse you pull when the drain disappears is the circuit where the drain is located. Then, keep searching just that section of the circuit until you find the specific source of the drain. Good luck.

 

Lots of outstanding advise. I am on it all day today. The meter I am using is reading in DCV which I assumed to mean voltage. There is a DCA scale which I would assume to mean amps.