Brand new battery drained overnight! Why?
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Joined: Aug 2002
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From: Bay Area, CA
Brand new battery drained overnight! Why?
I just put a brand new battery in an '85 on sunday and turned the key and the car turned on and started. Well monday i put the key in the ignition and turned it. But nothing happened, The brand new battery was completly drained. I charged the battery and was able to get it to start again, but then it simply just drained again overnight. Does anybody know what could cause this to happen? And how i might fix it. I'm guessing it might have something to do with the electrical or wiring or something, but i'm not 100% sure.
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Joined: Jul 2003
Posts: 198
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From: San Antonio, Texas
Yea, I bet it is electrical. 
MeaCulpa is right. It is probably a short, or something left 'on.'
Based on your sig, the car has been sitting a long time, so you likewise don't know what might have killed the first battery (or if it might be good).
One way to approach it is measure current from the battery (the multi-tester manual will tell you how to do this). Then, one by one, start pulling fuses to see which stops the current. Whichever fuse pulled stops it, tells you which component to check for 'stuck on' (e.g. storage bin lights) or shorted out.
Another method is to figure out which electrical system is not functioning (e.g. headlight motors or power windows)...most shorts cause the associated component not to work.
Happy hunting
Brian T. C.
MeaCulpa is right. It is probably a short, or something left 'on.'
Based on your sig, the car has been sitting a long time, so you likewise don't know what might have killed the first battery (or if it might be good).
One way to approach it is measure current from the battery (the multi-tester manual will tell you how to do this). Then, one by one, start pulling fuses to see which stops the current. Whichever fuse pulled stops it, tells you which component to check for 'stuck on' (e.g. storage bin lights) or shorted out.
Another method is to figure out which electrical system is not functioning (e.g. headlight motors or power windows)...most shorts cause the associated component not to work.
Happy hunting
Brian T. C.
1) A "bad ground" will NOT cause a battery to drain, only a continuous load will. Something in your electrical system is always ON. Here are some things for you to try...
Some will disagree with this method, but I have taken this approach many times to isolate electrical drain problems. A couple of warnings though...
IF YOU ARE USING A LEAD-ACID BATTERY, MAKE SURE THE CAPS ARE ON TIGHT!!!
MAKE SURE ALL DOORS ARE CLOSED AND ALL LIGHTING IS OFF
WHILE I HAVE NEVER EXPERIENCED ANY PROBLEMS WITH THIS METHOD, IT IS (THEORETICALLY) POSSIBLE THAT DAMAGE COULD OCCUR TO SOME SENSITIVE COMPONENTS, SO BE CAREFUL. IF YOU KNOW HOW, YOU MAY WANT TO DISCONNECT THE ELECTRONICS MODULE FOR THE ENGINE BEFORE PROCEEDING, JUST FOR SAFETY.
Remove the positive battery terminal. When there is a current drain and the battery terminal is re-connected you will see a spark at the terminal. Keep in mind there are a couple of items that always draw a small amount of current (i.e. clock, stereo memory, etc.) but if things are operating correctly the spark you experience will be very small. For the type of battery drain you are experiencing, you will see a significantly bigger spark.
First, have you added any electrical items recently? (i.e. stereo, gauges, lighting, etc.) If so try disconnecting these first. You can do this by removing the fuse. Remove one item at a time then "reconnect" the battery terminal by touching it to the top of the battery. What you are looking for is a significant decrease in the amount of spark you experience.
If this is not productive, remove the fuses from your fuse box one at a time, again checking the spark each time you remove a fuse. When you see a significant decrease in the spark you have found the faulty branch.
At this point, if you don't already have a wiring diagram, GET ONE. This is the most accurate way to tell exactly what is on any given circuit. For example, on my '83 GSL fuse #3, which is for the cigar lighter, interior light, key reminder and hatch release also supplies power to the digital clock. The only way you will know this is by looking at the wiring diagram.
Once you have identified the faulty branch and have a wiring daigram, you can disconnect one item at a tiem for that branch until you find exactly where the problem is.
Keep in mind, you may not find one faulty item, even after you have identified the faulty branch. If this is the case you may have a wire that has rubbed against the chassis, or some other metal object, until it has worn the insulation off the wire. To fix this you can either replace the wire, which may be pretty expensive or another option might be to patch the insulation. Go to Radio Shack, or some other electronics store, and buy some Heat Shrink Tubing just big enough to fit over the wire. Next cut the wire at the worn spot. Put the heat shrink over the wire and splice the wire back together. I would recommend soldering to ensure a good connection. Once you have done this position the heat shrink tubing directly over the splice and apply GENTLE heat. BE CAREFUL not to damage other wires in the process.
Yet another option may be to use a "butt connector" to repair the wire. Cut the wire at the bad spot and then crimp the butt connector in place.
This is pretty long, but I hope it helps.
Some will disagree with this method, but I have taken this approach many times to isolate electrical drain problems. A couple of warnings though...
IF YOU ARE USING A LEAD-ACID BATTERY, MAKE SURE THE CAPS ARE ON TIGHT!!!
MAKE SURE ALL DOORS ARE CLOSED AND ALL LIGHTING IS OFF
WHILE I HAVE NEVER EXPERIENCED ANY PROBLEMS WITH THIS METHOD, IT IS (THEORETICALLY) POSSIBLE THAT DAMAGE COULD OCCUR TO SOME SENSITIVE COMPONENTS, SO BE CAREFUL. IF YOU KNOW HOW, YOU MAY WANT TO DISCONNECT THE ELECTRONICS MODULE FOR THE ENGINE BEFORE PROCEEDING, JUST FOR SAFETY.
Remove the positive battery terminal. When there is a current drain and the battery terminal is re-connected you will see a spark at the terminal. Keep in mind there are a couple of items that always draw a small amount of current (i.e. clock, stereo memory, etc.) but if things are operating correctly the spark you experience will be very small. For the type of battery drain you are experiencing, you will see a significantly bigger spark.
First, have you added any electrical items recently? (i.e. stereo, gauges, lighting, etc.) If so try disconnecting these first. You can do this by removing the fuse. Remove one item at a time then "reconnect" the battery terminal by touching it to the top of the battery. What you are looking for is a significant decrease in the amount of spark you experience.
If this is not productive, remove the fuses from your fuse box one at a time, again checking the spark each time you remove a fuse. When you see a significant decrease in the spark you have found the faulty branch.
At this point, if you don't already have a wiring diagram, GET ONE. This is the most accurate way to tell exactly what is on any given circuit. For example, on my '83 GSL fuse #3, which is for the cigar lighter, interior light, key reminder and hatch release also supplies power to the digital clock. The only way you will know this is by looking at the wiring diagram.
Once you have identified the faulty branch and have a wiring daigram, you can disconnect one item at a tiem for that branch until you find exactly where the problem is.
Keep in mind, you may not find one faulty item, even after you have identified the faulty branch. If this is the case you may have a wire that has rubbed against the chassis, or some other metal object, until it has worn the insulation off the wire. To fix this you can either replace the wire, which may be pretty expensive or another option might be to patch the insulation. Go to Radio Shack, or some other electronics store, and buy some Heat Shrink Tubing just big enough to fit over the wire. Next cut the wire at the worn spot. Put the heat shrink over the wire and splice the wire back together. I would recommend soldering to ensure a good connection. Once you have done this position the heat shrink tubing directly over the splice and apply GENTLE heat. BE CAREFUL not to damage other wires in the process.
Yet another option may be to use a "butt connector" to repair the wire. Cut the wire at the bad spot and then crimp the butt connector in place.
This is pretty long, but I hope it helps.
One thing I forgot to mention...make sure to check your alternator and starter too. It is possible you have a faulty rectifier in the alternator causing the current draw or even a faulty starter solenoid.
