High Output Alternator Recommendations

[DaveVA78Chieftain]

There are still a shunts in the circuit.   They are just not located in the gauge itself.  I can only speak to the original dash however becasue I do not know how the custom dash was integrated into the system.  So, for the alternator circuit (MAIN?) you can see the section of wire used for the shunt in the following diagram:



For the AUX, the principle is the same (shunt wire) however I do not know where they placed it.

The amp gauges are actually milliamp meters.  They are simply measuring the votage drop across across a section of wire that acts as a shunt rather than having the shunt inside the amp meter itself (old days approach).   

The section of wire is placed such that you are seeing the flow of current to and from the chassis battery.  Alternator current to battery down A20-10BK (Circuit A20; 10 gauge; black wire).  Chassis feed on A20B-10BK (Circuit A20B; 10 gauge; black wire).

Amp Meter leads (A1-18BK [Circuit A1; 18 gauge; black wire] and B1-18RE [Circuit B1; 18 gauge; red wire]) are soldered to either end of A20A-10BK (Circuit A20A; 10 gauge; black wire).  It is the resistance of the length of 10 gauge wire A20A that determines the voltage drop across A20A.

red wire is the shunt.  Grey wires are the meter leads.



http://www.sentex.ca/~mec1995/gadgets/shunts/shunts.html

Dave

[Wantawinnie]

Thanks Dave,

So there is not a way to use the original ammeters and the 120 amp alternator? I downloaded the 1973 chassis diagram and it appears to run full power to the ammeter. I can't find a shunt in there anywhere. The custom dash is not listed so the volt meter is not shown.

I am also wondering about the ignition switch. Since it appears that full power runs there how does it handle the increased load? That wire seems rather hard to change. Trying to figure all this out, not a big fan of wiring.

Thanks

[DaveVA78Chieftain]

You hve the RM400 not a M350 chassis. You need to look at the 74 wiring diagram where they changed to the wire shunt.  The 73 diagram you are looking at is for the M350 Chassis.  Easy way to check is what gauge wire is used at the amp meter.  Small 18 gauge or large 10 gauge.

Dave

[Wantawinnie]

It's the same heavy gauge wire feeding from alternator to the ammeter.

[DaveVA78Chieftain]

If using a 120 amp alternator, do not route the new cabling to the existing gauges.  The existing gauges are not rated for that high of amperage.  At some point the higher amperage will burn out the shunt rendering the gauge usless and possibly stranding you.  Your sort of stuck with the only option of replacing the gauges if you want to retain amp gauges.  A external shunt version is the best approach.

Dave

[Wantawinnie]

That's what I was afraid of. Any really good reason to even have any ammeter's if a volt gauge is present? I could actually use those spots for boost and tranny gauges anyway.

If bypassed can I just run a heavy wire right to the starter relay from the alternator? What about the ignition switch wire?

Thanks

[Wantawinnie]

I see in 1975 they bypassed the steering column wiring connector plug and ran the wire directly from the starter relay to the ignition switch. Probably because the connector heated up and would melt.(mine is starting to show signs of overheating)

Hoping that wire can stay smaller as the heavy wire would carry most of the extra alternator load. I would jump that connector to eliminate that weak spot.

Also, I see the fusible link was moved into the alternator to relay circuit in the 74-75 diagram.

[DaveVA78Chieftain]

I had to jumper most of the wires around that connector.  Known weak spot.
If they have anything more than a idiot light, todays vehicles only use voltmeter.  For monitoring to see if the system is charging that works fine.  I usually like to know both voltage and amperage but it is in some ways personal choice.  Alternator voltage output should stay in the 13.8 to 14.5 volt range.  Amperage will vary anywhere from a few amps to typically around 20-25 amps.  It can go higher depeding on the condition of the battery (SOC) and the amount of load on the system (fans, aux battery switch position, stereo system, headlights, etc.).
As far as tapping off for chassis loads, that should be via a fusible link.  Main consideration is to retain the central distribution/monitoring point that is located up by the voltage regulator in the 74-75 schematic.  You can change things around but the idea is to have the alternator maintain  common voltage level throughout the system (i.e. the central distibution point).  You can see that the original Dodge voltage regulator connected to that point very closely.  That solder connection is within 6" of the stock regulator.  Chevy P30 uses a distribution block mounted under the hood.

Here is a long winded but good description of the central tap used on chevy's.  It's the concept that is important, not the paticular application described.
http://www.madelectrical.com/electricaltech/chevymain1.shtml

Dave

[Wantawinnie]

Thanks Dave,

Can I get away with the smaller original size wire to the ignition switch if eliminating the ammeters and run a heavy wire from the alternator to relay? Not really sure how to go about upgrading that wire up in the column.

[Wantawinnie]

... Here is a long winded but good description of the central tap used on chevy's.  It's the concept that is important, not the paticular application described.
http://www.madelectrical.com/electricaltech/chevymain1.shtml

Dave

Dave

I read through that article and have been studying the '73 and '74-75 diagrams. The central distribution monitoring point is mainly composed of ignition related wiring. I don't have any of that with the diesel. The only power the engine has after start up will be a small wax filled KSB solenoid that adjusts timing after startup as the wax heats up. I clipped off all the ignition wiring and ran the hot lead that remained to the wax solenoid.

I guess what I am wondering is what to use for the 12V feed to tell the regulator what the system is doing now that there is no longer a distribution point. I've read on several diesel forums that when converting to a external regulator you hook up the two alternator field wires to the regulator and then also attach a 12V ignition source to the top regulator post. That setup seems pretty straighforward and nothing is ever mentioned about the actual 12V ignition feed used.

BTW: I have eliminated the two Ammeters and will be running a heavier wire from the alternator to the starter relay along with a fusible link. I also retained the fusible link to the main dash feed.

[DaveVA78Chieftain]

Not knowing specifics of what you have, is this what you are doing?
http://www.dieseltruckresource.com/faq/faq.php?display=faq&nr=161&catnr=20&prog=1&lang=en&onlynewfaq=1
That is with a Dodge regulator

Here is the Ford regulator approach
http://www.cumminsforum.com/forum/94-98-electrical/37468-alternator-external-regulator-how-89-02-a.html


The central distribution point ensures the votage is balanced to both ignition and accessories.  Like a wagon wheel where the hub is the center point so all loads radiating from that point see the same voltage.

Dave

[Wantawinnie]

Yeah, that is the basic idea. Those guys are bypassing their failed ECM which controls the voltage regulation on the 92 and later trucks. The 89-91 diesels used the older external voltage regulator design like the Winnebago had.

I guess, since there is no ignition voltage maybe where the 12V comes from on a diesel isn't a huge concern. i??

[DaveVA78Chieftain]

I was just trying to make sure I understood what you were doing.  The source would be a fused ignition source (fuse or fusible link) just like the original Dodge regulator was.  It is sourced from Ignition 1 (J10-16RE; Circuit J10, 16 gauge red wire) on the Dodge Ignition switch.   The section between the solder junction and the plug is J10G-16RE.  The alternator/regulator pulls very little current down that leg.  The solder junction shown on the Dodge drawing is located at the aft end of the intake manifold on passenger side.

Dave

[Wantawinnie]

J10-16RE is the wire I ran over to the KSB solenoid. I will connect that to the regulator for 12V power.

Thank you very much for the help Dave.

[DaveVA78Chieftain]

For reference this writeup provides a good overview of how Dodge products with an external regulator work.
http://ramchargercentral.com/electrical/understanding-the-dodge-charging-system/

Dave

[kb2crk]

Hello all
I know this is an old thread but I found something that might work. Chrysler from 1987 to 1989 made a compact alternator that is supposed to fit anywhere the old square backs did. They were rated for 90 or 120 amps. The one listed for the B series van has a 2 groove v belt pulley on it. I ordered one from Amazon to try the bolt up on the 440 in my 76 Travco. If it fits I will upgrade the charging wires and see how it works. The 78 amp square back it will be replacing has been replaced 2 times a year since I bought it under warranty. One issue is I am running two electric fans instead of the clutch fan. I have not installed the Fuel injection kit I have yet due to the voltage issues I have been having. I will update here on how it works out. The same alternator is available through Napa and inexpensive except for the core (Which I do not have). Amazon was an outright purchase and was under $130. Napa was 75 for the alternator and 60 for the core.

[legomybago]

How well does your rig pull the car? On hills and such.

[kb2crk]

How well does your rig pull the car? On hills and such.

Had issues climbing Fancy Gap a couple years ago but that was a half stopped up fuel filter and vapor lock in the carb. A week later going over Mont eagle in Tennessee We were maintaining 50 going up hill. That was with a Dodge Journey in tow that had replaced that SOrento. I have also pulled my 86 Dodge D150 behind it with no issue but no major climbs.

[kb2crk]

Well the 87 to 88 Mopar 50/120 alternator arrived and it looks like it will fit nicely. The charge stud is in the same clock location as the Denso but the alternator is not as deep. I need to order some pivot spacers to make sure it stays put with no undo stress on the ears.