I'm getting around to wiring the 3-wire alternator I bought from Autozone ('74 Monte Carlo $45 w/lifetime warranty) and wanted to check with everyone to see if I've got it right:
The alternator has a terminal on the back where the juice comes out and a two-pronged plug on the top to tell it to make the juice, how much juice to make and to let me know if it ain't workin' right.
The terminal on the back ( the 'battery' terminal) gets hooked up to the starter using a fusible link and heavy guage wire with some resistance. You can get the resistance using 'resistance wire' or a solid state resistor/diode. The resistance is so that the alternator doesn't overheat when its charging a low battery and doesn't heat up the battery too much when it is low, causing the fluid in the battery to evaporate and possibly frying the alternator by overheating it. The fusible link is to protect from a short in the starter.
The two-prong terminal on the side (AKA the 'DA') is marked terminal one (1) and terminal two (2).
Number two (2) terminal on the DA (thicker wire than NO. 1) is the voltage sensing terminal that tells the alternator how much juice to make depending on the state of the battery. The reason this thing exists is because from the factory the wiring used a junction box. The battery ran to the junction box and all the accessories hooked up to the junction box. To measure the voltage at the junction box you needed this extra wire. In the truck you can hook it up to the battery terminal on the alternator but you are better off hooking it up to the junction box (if you use one) or the starter, becuase that'll give the alternator a more accurate reading on volts. Whether this line runs to the Bat terminal, junction box or starter, it should include a fusible link to protect your alternator from a short circuit.
Number one(1) is the 'exciter' and hooks up to the ingnition switch (and optionally to an indicator light.) Somewhere between the alternator and the ignition switch I need to install a resistor (10 ohm 10 watt), so that when the car is turned off juice doesn't flow backwards from the battery through the exiter to the ignition switch and then to the coil, which would keep the truck running even after I take the key out. The 10 Ohm 10 Watt resistor is available at any radio shack (Part 1N4001, 4 for $3.50 I think). You can also buy this resistor from some vendors who sell it for $30.
Right?
