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Old 03-22-2015, 02:45 PM   #1
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Default Battery killer (where are my electrons going)

Car kills a battery over about 24 hours (90 chassis fully molested). Brand new battery that is a standard replacement. I have full voltage at the stop, hazard, CIG, and btn fuse.

I am going to measure draw from the battery later but right now I don't have a sufficient load to measure across to check this. Also it will lay waste to a battery with the alternator disconnected.

I am pretty sure all of those fuses are supposed to have voltage at them but want to double check myself. Any help or advice would be suuuuuuuuper appreciated!
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Old 04-05-2015, 04:52 AM   #2
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More troubleshooting shows .1A draw from the battery with the ignition off, pulled the stop fuse out and draw fell to .05A. I am pretty sure that isn't normal...potentially the relay? Resistance across the fuse is 115kΩ, 115kΩ from one leg to ground, and the other is 192Ω to ground.

All other fuses and the alternator yielded absolutely minimal amperage change (like 1mA). Any thoughts?
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Old 04-05-2015, 11:13 AM   #3
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I'm surprised that 100ma is enough to kill a battery in 24 hours, that would effectively make the battery have a 2.4ah capacity.

Are you certain that the alternator is putting out sufficient voltage to actually charge the battery fully?
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Old 04-05-2015, 03:08 PM   #4
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As long as your seeing below a 50mA drain on your system after a few minutes of key off, it's normal.
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Old 04-05-2015, 06:01 PM   #5
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I thought I would have a much larger drop as well but that was it. It may not be killing it in one day but seeing how the car is being rebuilt it will kill it really quickly due to never being started.

I agree 50mA would be good but with the brake light fuse in the drop is too much and doesn't seem right.
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Old 04-05-2015, 11:38 PM   #6
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0.05A draw is probably ok. Try pulling the radio fuse too, or any fuses until it drops to zero. Then you'll know what circuit(s) are pulling power.

If brake pulls power when OFF, my guess is switch is bad on the brake pedal. Try unhooking the switch (unplug it) and see if that circuit goes off.
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Old 04-06-2015, 12:18 AM   #7
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Are you running a megasquirt? Log your next drive and check out the voltage curve to make sure it seems relatively constant at an appropriate voltage.
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Old 04-06-2015, 04:22 AM   #8
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Car isn't driving yet but is close, I am running MS1 so I'll check the log when it starts going again.

Every other fuse I pulled yielded no change including the radio. I think that the large draw was the horn relay...the NB wheel I installed had all of the little plastic pieces broken that insulate the horn springs and bolts. I made it work for now but I am sure it will fail again.

I still feel there is an underlying problem. I gotta check the draw again now that the horn thing is fixed.
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Old 04-06-2015, 09:27 PM   #9
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Quote:
Originally Posted by astroboy View Post
Car isn't driving yet but is close...
Jesus you have been saying that for years....

Post updates.
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Old 04-06-2015, 10:26 PM   #10
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You fill me with sadness. Hawaii has vehicle recon and they mandate everything safety related is installed and working and stock ( airbag, seat belts, horn, side markers, crash pad/bar for the bumpers, cat, and so on). Why not come out and help me finish her off?
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Old 04-06-2015, 10:30 PM   #11
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Because sadly I quit my job, so I will no longer be going out there. I actually quit like the day after you called me, but I couldn't say anything because there were coworkers standing around me when we were talking. Started a new one in January that doesn't require travel to Hawaii unfortunately .

A trip to Hawaii is a lot harder when its not on the companies dime, lol.
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