Battery Draining
Thread Starter
Cruising
Joined: Jan 2010
Posts: 12
Likes: 0
Battery Draining
I am a newby to Corvette Forum but I need help. I am restoring a 71 coupe, all new wiring harness, new switches, fuses, the whole nine yards. Everything works but with every thing off it drains my new battery overnite. Any suggestions?
Burning Brakes
Joined: Mar 2005
Posts: 861
Likes: 0
From: WNY
I would do is check to see if its grounding out - Are you handy with a multimeter? Its a really simple process, just takes a lot of time.
First thing I would do is see how many ohms you are pulling at the battery with everything hooked up and the key off. That will tell you quite a bit.
First thing I would do is see how many ohms you are pulling at the battery with everything hooked up and the key off. That will tell you quite a bit.
Instructor
Joined: Nov 2006
Posts: 122
Likes: 0
From: TX
I worked on a battery drain problem for days. Finally found that the glove box compartment switch was not being fully depressed, and the light was on, but couldn't be seen since the compartment door was closed.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
Drifting
Joined: Apr 2008
Posts: 1,992
Likes: 56
From: Antioch IL
I worked on a battery drain problem for days. Finally found that the glove box compartment switch was not being fully depressed, and the light was on, but couldn't be seen since the compartment door was closed.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
that is the best way pul one fuse at a time until you find the right circuit.
Melting Slicks
Joined: Sep 2005
Posts: 2,667
Likes: 853
From: Warminster PA
I worked on a battery drain problem for days. Finally found that the glove box compartment switch was not being fully depressed, and the light was on, but couldn't be seen since the compartment door was closed.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
Use a DVM, digital volt meter, and set it to read DC Amps. On some meters you need to move the test leads to different inputs on the meter. Then disconnect the positive side of the battery. Put the red lead on the positive battery terminal and the black lead to the cable. With everything off you should read zero current. If you do read current then as suggested above, pull one fuse at a time to locate the offending circuit.
Good luck,
Tom
Intermediate
Joined: Nov 2005
Posts: 32
Likes: 0
Bad alternator diodes will also drain the battery, but I've never seem them drain the battery overnight.
Your battery may be shorting out as well. A hydrometer, which is cheap and simple to use, will tell the story on that one right away.
Also, like Tom said, you need a digital multimeter. I always check current draw by checking milliamp draw through the negative post although the battery is draining so fast that Tom's and other's suggestion at checking current voltage at the positive post will work and then the fuse pulling should get you there if it's not the battery or alternator diodes.
Good luck.
Your battery may be shorting out as well. A hydrometer, which is cheap and simple to use, will tell the story on that one right away.
Also, like Tom said, you need a digital multimeter. I always check current draw by checking milliamp draw through the negative post although the battery is draining so fast that Tom's and other's suggestion at checking current voltage at the positive post will work and then the fuse pulling should get you there if it's not the battery or alternator diodes.
Good luck.
Intermediate
Joined: Nov 2005
Posts: 32
Likes: 0
I left the computer and thought about your battery drain again. If your clock is working then you're going to read 12 volts with Tom's suggestion. You need to measure current flow. You can do that by getting a digital multimeter and reading the instructions on measuring current flow.
Both the hydrometer and digital multimeter aren't that expensive and are good and necessary tools to have when you're chasing down electrical problems.
Both the hydrometer and digital multimeter aren't that expensive and are good and necessary tools to have when you're chasing down electrical problems.
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Instructor
Joined: Mar 2010
Posts: 112
Likes: 0
From: Rice Lake Wisconsin
drain
I worked on a battery drain problem for days. Finally found that the glove box compartment switch was not being fully depressed, and the light was on, but couldn't be seen since the compartment door was closed.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
You need to connect an ammeter in series with one of the battery leads, and get a reading on the drain current.
Then you can pull one fuse at a time, while looking for the drain to go away. That will get you on the right circuit to look at.
I always pull the drivers seat when I have to work in the fuse block area, it will save you a lot of time in the long run.
Melting Slicks
Joined: Sep 2005
Posts: 2,667
Likes: 853
From: Warminster PA
I left the computer and thought about your battery drain again. If your clock is working then you're going to read 12 volts with Tom's suggestion. You need to measure current flow. You can do that by getting a digital multimeter and reading the instructions on measuring current flow.
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To read voltage you would connect the meter from the positive terminal to ground. for the purposes of diagnosing this problem, voltage measurements won't help.
Tom
Intermediate
Joined: Nov 2005
Posts: 32
Likes: 0
JMS71VETTE is right. He is basically saying the same as I am. Drain and current flow or current draw are the samething. You just need the multimeter and its instructions on measuring current.
As for the fuse pulls it will show a bad circuit, but will not show a bad battery (use hydrometer) or bad alternator diode/s. However, if the fuse pulls don't show a bad circuit or eliminate the draw and the battery is good then the alternator should be checked.
As for testing the alternator, I use to diassemble the alternator and pull the diodes out to check them, but I think some shops can test it for bad diodes.
When you do the fuse pull make sure the courtesy light/overhead light is not on. I have forgot that many times.
As for the fuse pulls it will show a bad circuit, but will not show a bad battery (use hydrometer) or bad alternator diode/s. However, if the fuse pulls don't show a bad circuit or eliminate the draw and the battery is good then the alternator should be checked.
As for testing the alternator, I use to diassemble the alternator and pull the diodes out to check them, but I think some shops can test it for bad diodes.
When you do the fuse pull make sure the courtesy light/overhead light is not on. I have forgot that many times.
6th Gear
Joined: Mar 2010
Posts: 6
Likes: 0
From: Micco Florida
Since you put new harnesses in, check the wires going to the alternator plug they may be reversed. A easy way to check is after everything has cooled down put your hand on the alternator and see if it is a little warmer around the plug area. If it is wires are reversed.
Had this prob myself PO had it wired wrong, I think thats why he sold it, he could not fix it the good part is I got a new battery, alternator and battery wires and belt.
Had this prob myself PO had it wired wrong, I think thats why he sold it, he could not fix it the good part is I got a new battery, alternator and battery wires and belt.
Le Mans Master
Joined: Aug 2006
Posts: 7,411
Likes: 1,549
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Overnight drain solved!
Glad you figured it out since for me solving electrical problems has always been difficult.
How did you find out the a/c relay was bad?
How did you find out the a/c relay was bad?
Thread Starter
Cruising
Joined: Jan 2010
Posts: 12
Likes: 0
I called the company in Calif. that made the wiring harness. The guy there spent about 2 hours on the phone with me running test on Tues. then again on Wed. He narrowed it down to the alt. and air conition relay. Super people to deal with.
