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Old 08-01-2005, 08:39 PM
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New Alternator = Battery Drain

I recently installed a new GM alternator in my '65 Mustang. Eliminating the external regulator really cleaned things up. I had originally tried to go with a one-wire setup, but that was doomed from the start. The 3-wire setup is much better. Now it appears I have a battery drain somewhere. If I leave it sit for a couple of days, the battery is dead. I wired it according to a number of helpful posts on this site - even used an indicator light. Any thoughts on this? Thanks in advance.

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Old 08-01-2005, 09:12 PM
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Try This

1. Charge the Battery

2. disconnect negative battery terminal and connect muti-meter between negative post of battery and negative battery terminal

3. If there is a drain on the battery big enough to make it go dead there should be more than .4 milli amps registering on the meter.

4. if there is unplug one fuse at a time in the fuse panel until you find the one that makes the meter fall to the normal range. (trouble shoot that circuit to find problem)

5. if no fuse affects the meter reading disconnect the two wire plug from the alternator if that makes the reading fall to normal the alternator is a fault.

Hope this helps

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Old 08-02-2005, 11:46 AM
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Thanks. I'll give it a go.
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Old 08-02-2005, 01:59 PM
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Easy solution

Doc here,

Did it do this BEFORE you changed the charging system?

Quick and dirty Solution, Charge the battery up with a Charger, 10 amps 6 to 8 hours..Get a load test..If it passes,

Take it home, unplug ALL the alternator Wires and let it sit an equal amount of time, If it IS not dead, replace the have an OBF on the diode Pack forward biasing, and causing a load just sitting...

If It IS dead, do the load test on individual circuits as outlined in prior post..

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