Chevy Powermaster Alternator Install on 440 - How to Wire It?

[SR66]

I have Chevy a Powermaster 100amp Alternator and have been reading a few things online about people installing them on their Dodge motors.

From what I've read it should fit the stock brackets and line up with some shimming.

Its a 3 wire alternator and I have a 160amp one on my 57 that is wired that way. Alternator is wired to starter solenoid. Sense wire is also wired there and 3rd wire goes to idiot light on dash.

On the 440 alternator I understand its wired to the amp meter and back down to the starter relay. I've read that the amp meter can be bypassed and the rest of the wiring in that can be looped at the starter relay.

I would wire the Chevy alternator with 4 gauge wire to the starter relay and run the sense wire there too. I can add an idiot light to the dash for the 3rd wire.

The 440 alternator has a red and green wire. I understand the green wire is for the voltage regulator and the red goes to the ballast?

The green wire can be eliminated since the Chevy alternator is internally regulated.

But what about the red wire? I am not sure where it would need to go to maintain its function. Attach it to the alternator wire post or to the battery.

Or I am overlooking something about these two wires?

I know if I upgrade to an MSD ignition it would eliminate it the issue all together.

[SR66]

After more research I found the wires and VR can be removed.

[Rickf1985]

I was going to make a couple suggestions but when you mentioned the wire to the ballast resistor from the alternator I figured I would hold off. I would have to look at a wiring diagram to see what that wire does but the rest of it is simple. You pretty much had the rest of it figured out. I would have simplified it even more but best to do it the way you are familiar with. My question is this, if you are converting why did you not just go with a single wire alternator? You could install a volt meter in the dash which is much better than a light and eons better that a amp gauge.

[SR66]

I already had the Chevy Powermaster alternator sitting in the garage. It was previously on my 57 until I upgraded to a 160 amp alternator. So I figured I would put it to use on the Winnebago if it would work.

As far as single wire vs 3 wire I have always used the 3 wire set up.

Good information why here - http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

[DaveVA78Chieftain]

On the 440 alternator I understand its wired to the amp meter and back down to the starter relay. I've read that the amp meter can be bypassed and the rest of the wiring in that can be looped at the starter relay.

That comment applies to 1973 (rectangle instrument panel) and earlier motorhome chassis only that have the amp gauge shunt inside the Amp Gauge.  Dodge migrated to a external shunt based system in 1974 (3 round instrument panel) due the Amp Gauge failure issue.  For 1974 and later The actual shunt is a short section of 10 gauge wire in the Alternator B+ line between the alternator and starter relay.  The wires to the amp gauge are only 18 gauge in a shunt based design (voltage differential sense rather than current path).

Standard 3 wire alternator schematic (Voltage Regulator inside the Alternator):



Idiot light (or a resistor) would have to be added.  Original Amp gauge could be reused if:
1) Original 10 gauge black alternator to starter relay wire is reused, OR
2) The original amp gauge wires are wired into the replacement wire that provides the same resistance value between the to connection points that was present in the original 10 gauge wire.

A Shunt based digital gauge could also be installed.

For 1974 and later Dodge Motorhome chassis, the "Common Junction point" for Remote Sensing is located at the rear of the intake manifold on the passenger side.  However, given the very long distance between battery and alternator, the Starter relay is most likely the best sense point which would also provide more voltage to the headlights and marker lights also.

[SR66]

Success!

The Chevy alternator mounted up just fine with the existing brackets and some washer shimming. Ran a 6 gauge wire from the alternator to the starter relay and the sense wire there as well. Added idiot light to dash.

Works perfectly. Engine response seems better and lights are brighter.

[Rickf1985]

6 gauge max is 70 amp and that is very short duration. 4 gauge max, short duration is 100 amp. For a 100 amp charging system you should be running #2.  If you get a situation where your battery is a bit run down and you are charging the max for a couple minutes you will be burning wires.

Here is a chart that will help put it in perspective. Yes, this shows amps per load but you are charging a battery which is a load so same thing.

https://www.bluesea.com/resources/1437

[SR66]

Thanks for info and link. I'll check it out.


I wired the alternator according to Powermasters instructions.


Based on their chart a 85-105 amp alternator needs to be wired with 8 gauge for a length up to 7 feet


My run is just under 7 feet and I went with the 105-125 amp column and used 6 gauge wire.

[Rickf1985]

Really interesting on how two references can be so far apart. I personally think they are being far to conservative on their recommendations. That or their alternator is only putting out 70 amps and not 100. I have been doing automotive wiring for 45 years and I would not go that light. Your vehicle, your choice.

Here is one that will put the size and voltage drop into perspective for you. Note that it starts with 4 gauge but there is still a drop in voltage over seven feet. But also notice the maximum run for a 8 gauge wire at 100 amps.

https://www.wirebarn.com/Wire-Calculator-_ep_41.html

[SR66]

Well forgetful as I am these days I went out and checked the wire I put in.


Its actually a 4 gauge wire.

[Rickf1985]

Just a hint, wire tying your plug wires with the running parallel to each other can induce crossfiring. They can touch each other but cross at an angle, the more angle the better.