Testing the alternator on the deuce

[maddawg308]

I have a small current leak that is draining the batteries on the non-winch truck. Someone at Gilbert said I should test the alternator first, to see if the diode is the problem. He told me there was an easy test with a multimeter to check this diode problem. Can anyone shed some light on the test he is talking about, and how to do it?

 

[TacticalTruck]

Disconnect the ground cable from the battery and connect a test light between the cable and the negative post. It should glow from the drain. Start disconnecting stuff until the light goes out and there you have it. Whatever makes the light go out is the drain.
Jeff

 

[acetomatoco]

Are you leaving your dash lights on? Ya gotta remember to shut the master light switch off as part of your shutdown sequence.

 

[cranetruck]

When all switches are off, there is still a permanent connection to the regulator, a current measured in milliamps.

 

[maddawg308]

Is this current supposed to be happening to the regulator? It would seem to me that when the truck is off, and all the switches are off, there should be NO current drain from anything. This is where the first post comes into play with what the man at Gilbert show told me. That there shouldn't be any drain, but due to a faulty diode in the alternator, it does drain....

 

[cranetruck]

Well, the current is very small, less than 10 mA, it is a circuit that senses the presence of batteries and also a capacitor, that may leak, more if faulty.
Not enough to drain the batteries in months....