One wire Alternator with a twist and other wiring harness qustions.

[jarrodblake]

I have a 1970 C30 that I am doing a cummins swap on. I have upgraded the in cab fuse box with a 18 circuit box link here. http://67-72chevytrucks.com/vboard/s...d.php?t=800315

Now I am on to the engine bay side of the harness I plan on installing a relay box for all my add ons/ upgrades ( dual electric fans, headlight relays, several other lights, grid heater and on board air ETC.

I am going through the harness and I am rearranging a few things. As I have moved the battery behind the cab on the driver side.

At the moment I am trying to wire up my Alternator. I did the one wire conversion to the stock dodge Alternator. I have the main power wire coming off the Alternator going to the starter. Then I have the starter going to the positive terminal on the battery. My plan is to run the red 12R wire to a relocated junction block that connects to the relocated battery. I have three other terminals on the alternator one is for a positive keyed power wire, the second one is not used it is a field terminal. The third is a field terminal that is used for a diesel tachometer.

What should I connect the brown 16BRN wire to? I think it is for the charging light.

Can I use the wire that went to the coil the 20Y = 20W/OR/PPL for my switched power for the terminal on the Alternator?

This is what I am thinking about doing.

cummins c30 alt wiring by jarrod vanwinkle, on Flickr

This is the stock harness

stock v8 c30 engine bay wiring by jarrod vanwinkle, on Flickr

A link to the stock harness http://www.chrismeadtattoos.com/wiri...ruckwiring.jpg

I found this in another thread on wiring a gm one wire



Here is my Alternator the red wire is for the tachometer. The orange wire is for keyed positive (the sensing wire) the green wire is unused field.

IMAG2842 by jarrod vanwinkle, on Flickr

[starterman99]

That Alternator is a Denso externally regulated alternator. The green would have gone to the voltage regulator to control output. How did you convert regulation to make it one wire?

[jarrodblake]

Originally Posted by starterman99

That Alternator is a Denso externally regulated alternator. The green would have gone to the voltage regulator to control output. How did you convert regulation to make it one wire?

I used a Transpo Internal Alternator Regulator Conversion kit.






https://www.ebay.com/itm/Dodge-Cummi...53.m2749.l2649

[starterman99]

OK I didn't see the wires going into the back cover on your picture, that's why I ask.

[dmjlambert]

I can take a stab at answering your question about the brown wire. It is not used in a 1-wire alternator application. Normally it would be used to operate an alternator trouble indicator bulb in the dash (if you have that kind of dash), and is also used to tell the alternator to turn on (excite I believe they call it).

[jarrodblake]

Originally Posted by dmjlambert

I can take a stab at answering your question about the brown wire. It is not used in a 1-wire alternator application. Normally it would be used to operate an alternator trouble indicator bulb in the dash (if you have that kind of dash), and is also used to tell the alternator to turn on (excite I believe they call it).

Thanks, I was not sure if I needed the brown wire my main concern was that it goes in to the ignition switch. I was not sure if it provide power or if it needed power. I don't have the indicator light in my cluster.

As for the wire that went to the coil the 20Y = 20W/OR/PPL in the diagram My 20w wire is a white cloth wire from what I have read it is a resistor wire and only supplies 9 volts. I have repind the wire with a 12 gauge wire. It is a unfused wire Should I fuse it?

IMAG2971 by jarrod vanwinkle, on Flickr

I have I have two inline fused wires 20B/w and 18B both go to the battery but the diagram does not say what they go to anyone know what they are for and what amp fuse they use? I plan on running them to my relay box I has 3 extra fuse slots so I can convert it to a blade style fuse.

IMAG2972 by jarrod vanwinkle, on Flickr

[dmjlambert]

20B/w and 18B wires are for your battery gauge. It is an ammeter that measures the current going toward your battery during charging, and measures the current discharging from your battery when you are running accessories without the engine on. A necessary part of the ammeter circuit is an approx 6 ft section of 12 gauge wire that goes between the alternator and battery as shown in the factory wiring, I've highlighted it here in yellow.



The ammeter measures the voltage difference between each end of the highlighted wire, and that is translated to amps. Your new wire arrangement does not do anything useful for the ammeter, so you can remove the 20B/w and 18B wires with fuse holders.

[dmjlambert]

Originally Posted by jarrodblake

As for the wire that went to the coil the 20Y = 20W/OR/PPL in the diagram My 20w wire is a white cloth wire from what I have read it is a resistor wire and only supplies 9 volts. I have repind the wire with a 12 gauge wire. It is a unfused wire Should I fuse it?

OK the 20W/OR/PPL cloth covered wire that has faded to plain white, which went to the ignition coil, yes it is a resistor wire. So you've replaced it, with a 12 gauge wire, but where does it go in your new engine? I think most folks would replace it to provide power to an HEI distributor on a gasoline engine. That yellow wire is not needed for the starter.

[jarrodblake]

Originally Posted by dmjlambert

20B/w and 18B wires are for your battery gauge. It is an ammeter that measures the current going toward your battery during charging, and measures the current discharging from your battery when you are running accessories without the engine on. A necessary part of the ammeter circuit is an approx 6 ft section of 12 gauge wire that goes between the alternator and battery as shown in the factory wiring, I've highlighted it here in yellow.

Attachment 2021688

The ammeter measures the voltage difference between each end of the highlighted wire, and that is translated to amps. Your new wire arrangement does not do anything useful for the ammeter, so you can remove the 20B/w and 18B wires with fuse holders.

Thank you, I did not know they were for the amp gauge that is good to know. I am going to be doing the 76+ volt gauge conversion to my cluster as the dodge alternator is around a 120 amps. From what I have read the stock amp gauge will not support 100+ amps and could burn up the gauge or start a fire.

Originally Posted by dmjlambert

OK the 20W/OR/PPL cloth covered wire that has faded to plain white, which went to the ignition coil, yes it is a resistor wire. So you've replaced it, with a 12 gauge wire, but where does it go in your new engine? I think most folks would replace it to provide power to an HEI distributor on a gasoline engine. That yellow wire is not needed for the starter.

Yes I have read most people use it to run a HEI, I need a switched 12v power wire for my sensing wire for the alternator. I figure it would be the best wire to use as it would best represent load on the fuse box as in the fuse box it is a 12 gauge wire and it has nothing else on the circuit and would show the load on the fuse box as a whole. I was wondering if I should fuse it. But after more reading it needs to be unfused as if the fuse where to blow it would cause the alternator to send full power to try and make up for the loss of the sensing wire.

I am however considering using it as a switched power source to power the relay box. I don't know how many amps are needed to switch a relay on, but from what I have read I can use as little as a 4 amp fuse. So I don't think it would affect the sensing wire enough to matter?

[HO455]

The drawback of using the old resistor wire circuit for alternator sensing is if you have a voltage drop (Say 2 volts) in the circuit between the battery and the end of old resistor circuit at the alternator. The alternator would begin charging to bring the voltage it was sensing up to 14.5 volts. At that point your voltage to the battery would be 16.5 volts. Voltage sensing to control the alternator output should come from the battery. Batteries not tolerant of over or under charging.
There are too many points (i.e. connections and switches) for a voltage drop(s) to develop between the battery and the alternator sensing using the old resistor wire circuit for my comfort level. Just my opinion.
Have you read the Mad Electrical information on alternator operation? It may help answer your questions.
Here is the link if not.

http://www.madelectrical.com/electrical-tech.shtml

[jarrodblake]

Originally Posted by HO455

The drawback of using the old resistor wire circuit for alternator sensing is if you have a voltage drop (Say 2 volts) in the circuit between the battery and the end of old resistor circuit at the alternator. The alternator would begin charging to bring the voltage it was sensing up to 14.5 volts. At that point your voltage to the battery would be 16.5 volts. Voltage sensing to control the alternator output should come from the battery. Batteries not tolerant of over or under charging.
There are too many points (i.e. connections and switches) for a voltage drop(s) to develop between the battery and the alternator sensing using the old resistor wire circuit for my comfort level. Just my opinion.
Have you read the Mad Electrical information on alternator operation? It may help answer your questions.
Here is the link if not.

http://www.madelectrical.com/electrical-tech.shtml

Thank you, I had not though of that. and Ill give the link a read.

[VetteVet]

.............

Originally Posted by jarrodblake

Thank you, I did not know they were for the amp gauge that is good to know. I am going to be doing the 76+ volt gauge conversion to my cluster as the dodge alternator is around a 120 amps. From what I have read the stock amp gauge will not support 100+ amps and could burn up the gauge or start a fire.

I think you might be thinking of the old style amp meter which had all the current in the system flowing through it. They were set up to read 0---30---60 amps, which would have created problems if a 100 amp plus alternator were wired that way. The newer style ammeter does not flow but a few milli-amps of current through it, and instead it reads voltage potential between the alternator and the battery to measure charge and discharge.
There are hundreds of post 62 trucks that are using SI and CS style alternators with the OEM ammeters out there and they are not having problems with them.

If you wanted to keep the OEM battery gauge you would have to wire the charging system similar to the original or it wouldn't work. There is a lot of mis- information out there on wiring alternators the wrong way for the most efficiency even thought they will charge.




Yes I have read most people use it to run a HEI, I need a switched 12v power wire for my sensing wire for the alternator. I figure it would be the best wire to use as it would best represent load on the fuse box as in the fuse box it is a 12 gauge wire and it has nothing else on the circuit and would show the load on the fuse box as a whole. I was wondering if I should fuse it. But after more reading it needs to be unfused as if the fuse where to blow it would cause the alternator to send full power to try and make up for the loss of the sensing wire.

Your sensing wire for the alternator, I'm assuming it works the same as the GM styles, needs to be wired to the main circuit junction, where it can read the voltage drops in the truck circuit loads. With the GM internal regulated alternators it is wired full time hot," with no resistance", but I can't say how yours should be with the converted regulator. The wire for the HEI can be the same wire that was used for the OEM coil and points distributor, but you will not have a resistance in it. The HEI distributor needs a full 12 volts to run correctly. DjmLambert has an excellent thread complete with Pictures on using this method. It retains the stock look and does not use a spot in the fuse box as in the IGN Unfused. port.
http://67-72chevytrucks.com/vboard/s...d.php?t=708975

There was no fuse in the original schematic and the debate goes on on whether one is needed. A 12 gauge wire should be used from the firewall to the distributor.



I am however considering using it as a switched power source to power the relay box. I don't know how many amps are needed to switch a relay on, but from what I have read I can use as little as a 4 amp fuse. So I don't think it would affect the sensing wire enough to matter?

It would not have a problem switching on the relays as they only require a few milliamps of current and 8.5 volts would be plenty. BE sure to fuse the no. 30 side of the relays (battery and alternator power side) and connect The sensing wire from the alternator to the main relay on the no.87 terminal so the alternator can read all the voltage drops there from the other relays.
You realize that you are going to have a very large relay for that function. See expensive and it could leave you stranded if it fails.

Some relays need to be close to their loads for best efficiency, cooling fans and headlights for instance, so take that into consideration.

What does the Cummings swap involve? are we talking Diesel with no ignition except glow plugs, high pressure fuel pump, mechanical injectors ?