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Author
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Topic: Battery Drain
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-01-2006 04:25 AM
 
I have just about finished the restoration on my '68GT Convert. After getting the electrical system hooked up, I find that my battery drains down overnight. I tried pulling all of the fuses out of the box, and it holds a charge, but so far any of the fuses I put back in causes a slow drain of the battery. Anyone have a suggestion on the next step to take in order to find the electrical gremlin? Most of the wiring has been replaced. I had the guy in Texas go over the main underdash harness, so I think that is in good shape. Craig
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exlocal
Gearhead Posts: 1552
From: hacienda hts., CA, USA
Registered: Dec 2004
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posted 05-01-2006 09:01 AM
Try putting in the fuses one at a time with a voltmeter on the battery to see if there is a large drain when installing the fuses. If not, try installing just half of the fuses and see if the battery drains overnight. When you find the group of fuses that drains the battery, split that in half again. You will eventually find the circuit that is draining the battery. Good luck.------------------
reliving youth
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-01-2006 09:55 AM
quote:
Originally posted by exlocal:
Try putting in the fuses one at a time with a voltmeter on the battery to see if there is a large drain when installing the fuses. If not, try installing just half of the fuses and see if the battery drains overnight. When you find the group of fuses that drains the battery, split that in half again. You will eventually find the circuit that is draining the battery. Good luck.
Sounds like a good plan to me!Using an ammeter would be more accurate in finding a drain on the battery. [This message has been edited by Mark Ugrich (edited 05-01-2006).]
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-01-2006 10:22 AM
I will try that. So far the first two fuses I put back in each caused a slow drain. I will continue to work my way through all of them.Craig
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Scott H
Gearhead Posts: 1480
From: Chicago area
Registered: Mar 2005
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posted 05-01-2006 11:40 AM
Are you sure the battery isn't in backwards?  LOLThis doesn't have an alarm on it does it? Or the radio hooked up directly to the battery? If you've got a drain with the first two fuses, do you still have a drain with NO fuses? could be the drain is being caused before the fuse box, not after. It would be strange that you would have two separate circuits (the two fuses you tried) causing a drain. [This message has been edited by Scott H (edited 05-01-2006).]
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Tom G
Gearhead Posts: 1069
From: Bethlehem, Pa USA
Registered: Nov 2001
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posted 05-01-2006 08:12 PM
What is battery voltage after charging and car is off and no fuses 13.5 or better? Are brake lite on or possible emergency flasher? If you can narrow down the fuse that is the culprit> we can help find a cause. Does car have a cigar lighter installed? Aftermarket radio with a memory wire or power antenna connection? Bad rotary switch on dome lite control can cause a drain also.------------------
67 Mustang F/B 302 GT-40X FMS engine RPM Air Gap 650 Holley DP Crane 1.7 roller rockers, Edelbrock Performer Nitrous, Dynomax ceramic headers WCZ rated-T5, cable clutch MagnaFlow SS kit W/X Pipe 3.89 9". SSBC 4 piston Alum caliper fr disc Clearwater Aqua GT Clone Vintage wheel works 40 series 16X8 215 front 255/50 rear drag radials 308 RWHP@5800rpm 300 tq NA 385rwhp 380 w 75 shot 13.11 @111mph
88 GT (FiveOfastback's ride)GT 40 X Track Heat, BBK headers X pipe 5 spd 296 RWHP 315 RWTQ Red and Silver [This message has been edited by Tom G (edited 05-01-2006).]
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-01-2006 09:58 PM
I have been checking fuses. So far each one I check causes a drain on the battery. There aren't any drain items except the clock installed in the car. The drain is occuring with the ignition switch off. It is somewhere past the fuse block. With all of the fuses out, it holds it's charge. I can measure the voltage across the battery posts, but not load.Yes, the battery is in the correct way. :-) Craig
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-02-2006 05:58 AM
Is it possible for the fuse block to be bad?Craig
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-02-2006 10:38 PM
It would be unusual for the fuse block to be defective.Try this, disconnect the positive battery cable. connect an ammeter with one lead one the battery post and the other on the battery cable.put all the fuses back in and check to see how many amps are being drawn.Now remove the fuses one at a time until there is no amp reading on the meter. the fuse that stops the drain is the circuit you need to investigate.
If none of the fuses stop the drain, disconnect the wiring to the alternator.It is possible for a bad diode in the alternator to drain the battery also.
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-03-2006 02:46 PM
Thanks, I will try that. Craig
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-13-2006 09:11 AM
I found part of the problem. I was using an aftermarket set of battery wires. The positive lead was 4 guage and I liked it being heavier than the original. Unfortunately it was longer also, and apparently it rubbed when the engine was running. A hole ended up being worn through the insulation, and it was touching the back of the alternator. Why this didn't cause a huge short I am not sure, but it did cause a definite drain. That masked whatever else is wrong to some extent. Now it is time to go back and check each fuse circuit for the problem.
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-13-2006 03:44 PM
Man, were you lucky! That kind of stuff can cause a fire. A drain is certainly the lesser of two evils. 
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-19-2006 12:57 PM
As I have been fumbling around with this, I realized that my alternator is now magnatized from being in contact with my battery cable. It still charges and appears to work o.K. Is this a problem?Craig
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-19-2006 04:07 PM
An alternator is actually a big electro-magnet.I know on the G.M. stuff the rear alternator bearing will become magnatized when the engine is running, it's a quick way to tell if the alternator is working. I don't think it's a problem.
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 05-21-2006 10:15 AM
Thanks. Mark
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 05-21-2006 03:10 PM
You're welcome! 
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CraigStephens
Journeyman Posts: 39
From: Atlanta Area
Registered: Jan 2006
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posted 06-11-2006 12:27 PM
Finally, I have had a day at home to work on the car! Using a volt/amp meter I was able to trace the drain to the alternator. At least the drain stops when I disconnect it.
The car is slightly modified in that a '69 351W is in the engine bay. What are the collective thoughts on a replacement alternator? Single wire thus bypassing the voltage regulator, or stock?Craig
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Mark Ugrich
Gearhead Posts: 351
From: Waukesha, Wisconsin,U.S.A.
Registered: Jan 2006
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posted 06-13-2006 12:09 AM
Craig, If you don't mind the car not being 100% stock I think I'd try a single wire alternator.The only downside I can think of is that you'll have to wait a couple of seconds for the alternator to self energize.
Spend enough money to get a quality unit and run a 8 or 10 gauge wire from the alternator to the positive side of the starter solenoid.(battery cable)
I'm not sure if the stock amp/volt gauge runs through the original voltage regulator,so it might be a good idea to install an aftermarket volt gauge.If done right it should be a really clean installation.
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