mr98z71
I'm Awesome
I just wanted to do a quick write up and add a little more info to the existing thread on swapping the factory alternator with the High Output Alternator (AD244) from the newer trucks (99-05). I am also going to have to say That I am not responsible for anything that happens to your truck, be safe, disconnect your battery before doing any electrical work, always double check your work. I would say this is one of the best mods that I have done to this truck but do it at your own risk… I am doing this because when I swapped my alternator, I would have liked to have known what I know now about Alternators but this info was not found in the existing threads. I spent countless hours reading up on how 3 Wire alternators works and how you can use a 3 Wire alternator to it's full potential with only one mod, so I figured I'd share this info with those who are interested.
So starting off, the first Alternators to come out were self exciting alternators. They would not always charge at low rpm (i.e. stopped at a light in rush hour). They then came out with Alternators that were electronically excited by a wire that ran from your gauge cluster in series with a resistor.
Alternators used to have their voltage externally regulated but modern technology has allowed them to have the voltage internally regulated using an internal Voltage regulator. This Voltage Regulator will regulate the voltage to 14.5 Volts give or take. Here's where it gets interesting for those of you who are not electrically inclined lol! Whenever you pass current through a wire, wether it be a 22 gauge wire or a 4O wire, there will be a voltage drop. As a wire gets hotter (due to ambient temperature or a higher current being drawn), there will be a higher voltage drop. Voltage = Ohms x Amps. Re-arrange that equation, Ohms = Voltage/Amps. There is a chart that comes in handy and will give you the total resistance in a wire/1000 Feet. I will demonstrate using a 10 gauge wire. A 10 Gauge wire has 0.9989 Ohms/1000 Feet. Say the wire going from your battery to the junction box is 10 feet long, the wire will have 0.009989 Ohms of resistance. Now is where we take our formula, (V = O x A), and we will say your alternator is going full bore (140 A), 0.009989 X 140 = 1.398 V. Now what did that give us you ask, Voltage drop. That means that if your alternator is charging at 14.5 Volts (at the source), by the time Voltage gets to the junction box, it is at 14.3 Volts. Energy cannot be created or destroyed, it can only be transferred. Your are basically "trading" .2 Volts to Heat up the wire. I am not going to calculate Voltage drop for all different size wires, that Is for you to do, I gave you the formula.
Now, the bigger the wire, the less resistance it will have per 1000 Feet, therefore you will minimize the amount of Voltage drop. I realize the 10 Gauge is not the exact size wire going from the battery to the JB in our trucks but I used it for an example. Now, there are two things that can be done here, you can either run a big 4 Gauge wire or bigger from the Battery to The JB, another big wire from the Alternator to the Battery and a Ground (AKA Big Three upgrade). The easiest way to compensate for this Voltage drop, is to use what is already built into these 3 Wire Alternators, looking right at us, called the sensing wire. You will notice when you look at the Oem Alternator plug, it has provisions for 4 terminals but it only has one pin in it. Look at the alternator itself, it's also got 4 Pins on it. Did the Manufacturer just put these in because they had some extra material? Probably not. These Connections are know as P.L.I.S. The Terminals are used for the following:
P= Used to drive a tachometer (Mostly for Diesels)
L= To Indicator Lamp
I= Used To Excite Alternator
S= Sensing Wire
Terminal "S" is the one that we are interested in. These Alternators have a built in remote sensing wire. This wire is normally used to sense Voltage at a remote location like your Junction Box, if it is not connected, the alternator will default to 14.5 volts output. Using the example above, if you route a wire from the JB to this terminal on the alternator, if the Alternator senses that the Voltage is 14.3 Volts at the JB, it will charge at 14.7 Volts to compensate for this Voltage Drop. So Now, You will have 14.5 Volts at the JB. All that I did to modify the OEM plug was add one of the wires from the plug that I grabbed off the AD244 At the junk yard, drill and file a slot in my oem connector and the wire from the Ad244 snapped right into my oem connector.
Now, the only problem that I can see by doing this mod is, since the alternator charging wire goes directly to the battery, If you have a significant Voltage drop to your JB, although the Alternator will compensate for this "drop", it may overcharge the battery. If for whatever reason, you have .5 Volts being lost from the Battery and the JB, your alternator will now charge at 15.0V which may overcharge the battery or boil the water out of it if you do not have a maintenance free battery. Like I said, do this mod at your own risk, I am going to try it, so far, my headlights are brighter, my interior lights are brighter and my power hungry amps are also happy. If you are looking at doing the AD244 Swap, I will tell you this, it is worth every penny. I got mine from a junk yard for $30. Just having your truck running, you are drawing around 40Amps, With it running, fan on high and both my stereo amps going, the Alternator was charging at 83 A. Now that I know this, I'm surprised that my Oem Alternator was keeping up lol!
So starting off, the first Alternators to come out were self exciting alternators. They would not always charge at low rpm (i.e. stopped at a light in rush hour). They then came out with Alternators that were electronically excited by a wire that ran from your gauge cluster in series with a resistor.
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Alternators used to have their voltage externally regulated but modern technology has allowed them to have the voltage internally regulated using an internal Voltage regulator. This Voltage Regulator will regulate the voltage to 14.5 Volts give or take. Here's where it gets interesting for those of you who are not electrically inclined lol! Whenever you pass current through a wire, wether it be a 22 gauge wire or a 4O wire, there will be a voltage drop. As a wire gets hotter (due to ambient temperature or a higher current being drawn), there will be a higher voltage drop. Voltage = Ohms x Amps. Re-arrange that equation, Ohms = Voltage/Amps. There is a chart that comes in handy and will give you the total resistance in a wire/1000 Feet. I will demonstrate using a 10 gauge wire. A 10 Gauge wire has 0.9989 Ohms/1000 Feet. Say the wire going from your battery to the junction box is 10 feet long, the wire will have 0.009989 Ohms of resistance. Now is where we take our formula, (V = O x A), and we will say your alternator is going full bore (140 A), 0.009989 X 140 = 1.398 V. Now what did that give us you ask, Voltage drop. That means that if your alternator is charging at 14.5 Volts (at the source), by the time Voltage gets to the junction box, it is at 14.3 Volts. Energy cannot be created or destroyed, it can only be transferred. Your are basically "trading" .2 Volts to Heat up the wire. I am not going to calculate Voltage drop for all different size wires, that Is for you to do, I gave you the formula.
Now, the bigger the wire, the less resistance it will have per 1000 Feet, therefore you will minimize the amount of Voltage drop. I realize the 10 Gauge is not the exact size wire going from the battery to the JB in our trucks but I used it for an example. Now, there are two things that can be done here, you can either run a big 4 Gauge wire or bigger from the Battery to The JB, another big wire from the Alternator to the Battery and a Ground (AKA Big Three upgrade). The easiest way to compensate for this Voltage drop, is to use what is already built into these 3 Wire Alternators, looking right at us, called the sensing wire. You will notice when you look at the Oem Alternator plug, it has provisions for 4 terminals but it only has one pin in it. Look at the alternator itself, it's also got 4 Pins on it. Did the Manufacturer just put these in because they had some extra material? Probably not. These Connections are know as P.L.I.S. The Terminals are used for the following:
P= Used to drive a tachometer (Mostly for Diesels)
L= To Indicator Lamp
I= Used To Excite Alternator
S= Sensing Wire
Terminal "S" is the one that we are interested in. These Alternators have a built in remote sensing wire. This wire is normally used to sense Voltage at a remote location like your Junction Box, if it is not connected, the alternator will default to 14.5 volts output. Using the example above, if you route a wire from the JB to this terminal on the alternator, if the Alternator senses that the Voltage is 14.3 Volts at the JB, it will charge at 14.7 Volts to compensate for this Voltage Drop. So Now, You will have 14.5 Volts at the JB. All that I did to modify the OEM plug was add one of the wires from the plug that I grabbed off the AD244 At the junk yard, drill and file a slot in my oem connector and the wire from the Ad244 snapped right into my oem connector.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
Now, the only problem that I can see by doing this mod is, since the alternator charging wire goes directly to the battery, If you have a significant Voltage drop to your JB, although the Alternator will compensate for this "drop", it may overcharge the battery. If for whatever reason, you have .5 Volts being lost from the Battery and the JB, your alternator will now charge at 15.0V which may overcharge the battery or boil the water out of it if you do not have a maintenance free battery. Like I said, do this mod at your own risk, I am going to try it, so far, my headlights are brighter, my interior lights are brighter and my power hungry amps are also happy. If you are looking at doing the AD244 Swap, I will tell you this, it is worth every penny. I got mine from a junk yard for $30. Just having your truck running, you are drawing around 40Amps, With it running, fan on high and both my stereo amps going, the Alternator was charging at 83 A. Now that I know this, I'm surprised that my Oem Alternator was keeping up lol!
