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928-recent virgin
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86 928 battery drain
I got something draining my battery. other than taking each fuse out and then touching battery post for sparks, is there a common problem i search for first?
thanks
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1986 928s black on black 1971 Ford Mustang Conv |
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02-20-2013, 05:30 PM
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Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
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Meter works better than looking for sparks.
The 928 brain doesn't go to sleep for a few minutes after the key is turned off and I "think" all the doors are closed, so until it sleeps some extra current flow is normal, and it never drops to zero. Min is something like 20 to 40 ma. Two most common culprits are a short in the wires to the interior light above the rear view mirror and faulty pin switches at the doors or hatch, with the latter lighting the warning red square below the door latch at the door jamb. My cars have been through a FEW times, and I still have a battery switch on both to disconnect the battery. I use a Gama side post battery disconnect switch, $13 shipped on ebay from jgama. I needs about a 1/2 "spacer" to raise the switch up off the rear panel where the ground strap connects, I used a brass plumbing fitting for a 3/8 compression fitting and a M8 bolt from Home Depot with thread matched to the bolt used in the car. |
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02-20-2013, 10:17 PM
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What's Facebook?
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Leaving key in ignition on my '86 will drain the battery.
Get yourself an inexpensive digital meter that reads milliamps. After properly setting up the meter, put it in series with the negatve battery terminal. Don't overlook the obvious......the battery may simply be going bad and discharging internally.
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Turborat "’Cause every once in while, the lion has to show the jackals who he is” 1979 911 SC - 2100 LB track rat 1986.5 928 5-Speed - 36,000 miles 2001 330Ci |
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02-21-2013, 01:59 PM
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Registered
Join Date: Jul 2001
Location: Wilmington, NC USA
Posts: 635
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A potential large drain is the defroster. If your defroster relay is bad,when you push the defroster button in for max defroster the defroster will stay on even after you shut off the car. It is supposed to turn off after 15 minutes or when the car is turned off. It drains in amps. Doesn't take long to drain a battery. If the relay is bad, restarting the car resets it and turns off the defroster
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69 911 2.3Ez 85 928S |
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02-22-2013, 03:54 PM
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Registered
Join Date: Nov 2007
Posts: 55
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Very common for the red door open marker lights to be illuminated when the door is closed. The door switches becomes corroded and make a ground contact.
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Tony B 1982 Blk/Blk 5.0L Hybrid Blown 10 psi 500 HP |
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02-22-2013, 07:33 PM
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Dancer
green machine
