Re: Alternator help needed

["Jim Blair" <carnuck@xxxxxxxxxxx>]

A: On the Delco alt, if you leave the I wire hooked up, and the motor not 
running, either the battery will go dead or the magic smoke will escape. 
Other than that, if you turn your car off and have that wire hooked up to an 
ignition lead w/o a 10 ohm resistance, the car will either A: Keep running 
or B: shut off and smoke ensues. This depends whether your ignition shuts 
off to a dead short in the power wire to the coil + (or whichever wire you 
hook the alt to) or it just goes open. If the motor is running and you have 
the alt excited, then ground the "I" (or is it "S"? The one I have outside 
my doorstep is labelled 1 and 2) lead then it will blow the alt (regulator) 
or melt the wire (whichever is weaker).
   You can actually start a car with the Delco SI alternator, and with the 
little red wire hooked to the battery + as well as the main terminal, you 
can momentarily jumper the "I" wire to the main terminal, battery + or 
anyplace that has power, and the alt will engage till you shut the car off 
or the spinning drops so low it diesengages the regulator.


From: Matt Haas <mhaas@xxxxxxx>
Subject: Re: Alternator help needed

This is wrong. If you attach the field wire directly to 12 volts, the magic
smoke escapes from the electronics. Once that happens, the alternator is 
dead.

The field wire needs to have some resistance in it to keep this from
happening. In a car with a warning light, the light bulb takes care of the
resistance. If you don't have a warning light (you need a voltage gauge in
this case), you need a resistor in the circuit. If you don't hook that wire
up to anything, the alternator will not charge.

The other wire is a voltage sense wire. That wire can be hooked to the
battery charge terminal but a better place would be either to the battery
post, the battery cable where it attaches to the solenoid, or (if your car
has one), a power distribution block. If you leave this wire disconnected,
the alternator will produce max amperage and will burn out in short order.
If you're really lucky, this could also set your wiring harness on fire.

If you want a real one wire alternator, you need to get one that has
self-exciting guts. I think the difference is just in the electronics but
there are a lot of real one-wire Delco 10si style alternators on the
market. PowerMaster (I have one of these) makes them that work both ways
for more flexibility.


Matt