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Wisc Joe – First off, the test where you remove the battery cable then insert a voltmeter between the battery post and the cable is gonna show only battery voltage. It cannot measure leakage current draw! (You are merely measuring the voltage between the battery positive and the rest of the system.) A reading of 12.6 volts is exactly what you should see. Further, a reading of 3 volts after you disconnect the wire from the BAT terminal is about what I’d expect. (Actual reading will depend mostly on the internal resistance of your particular voltmeter) Rather, to measure leakage current you must set your meter to the DC current mode, then connect it between the battery post and the disconnected cable. Start with the meter at it’s highest current setting (usually 10 amps) then work downward one currently increment at a time until the meter begins indicating. And ABSOLUTELY DO NOT turn on the any electrical loads (ign switch, lights, etc) while doing this test!! (Fail to observe this and you risk smoking your meter!) For a generator-equipped system the current draw under this test should be almost 0 milliamps, even with the meter set on the low milliamp range. However for a alternator, standby draw could run as high as 10 – 20 milliamps and still be OK. Readings higher than this usually mean a bad regulator or a problem (a failing diode) inside the alternator. Hope this helps!
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