The Stovebolt Site Forums The Shop Area The Electrical Bay Ammeter Gauge and Alternator Questions

I did a search on here and I think I have all I need to rewire my 52 Chevy. I have a few questions below.

1. Is the positive side on the Ammeter gauge the charge or discharge side. I would guess the charge side is positive but I want to be sure.

2. My regulator only has three connections BAT, FLD, ARM, instead of four like I printed out from this site. Also my alternator has a red wire jumpered from R to Bat. So I am a little unclear on how to wire my alternator.

Does the Bat side of the alternator go to the neg. side of the ammeter? And then FLD and R go where?

Any help is greatly appreciated.

Rcimp

Rcimp,

I have a tough time remembering the backside of the ammeter too, but I'm pretty sure that + side goes to the BATT...this would make it the 'charge' side.

The regulator that has only three terminals..BATT, FLD and ARM can only be used with a generator. The regulator for use with a old style externally regulated alternator has four terminals...as you noted. If you have this style alternator, you need a different regulator.

The other questions will depend on what type of charging device you actually have.

Stuart

Ok I am going to buy a VR138 regulator from NAPA. It has the four conections that are in the diagrams I downloaded. What about the red wire jumpered from the R to the BAT on the alternator. Do I remove it or should I just leave it?

Rcimp,

I'm still not sure what's going on. The wisest move would be to forget the VR138 and opt for a new internally regulated alternator...almost as cheap as the regulator. This allows you to get rid of the sometimes problematic voltage regulator.

The safe method would be to run 'R' to #2 on your new regulator (if you go that route). This is where it belongs.

I don't know why it was wired this way before. I would wire it the way it appears in the diagram you found when doing your search.

I can't say this enough, if you aren't concerned about a stock appearance, then the newer alternator, or even a single wire alternator should be right smack dab on the top of the list.

I'm not totally convinced you don't have a SI, or internally regulated alternator right now.

Stuart

Rcimp,

Where does your DA plug attach to the alternator...on top, or on the back of the case?

Stuart

It plugs in the back of the case. I am not concerned about stock apperances. This truck is mainly for my wife to putt around in so I want it reliable.

If I go with an internally regulated alternator then how do I wire it up?

If I go with a one wire Alternator then the one wire from the alternator just gets wired to the neg side of the ammeter right?

Thanks for your input Stuart.

Rcimp,

You are correct on the wiring location of the single wire unit. If you use a three wire unit, BATT will also connect to that ammeter location. #1 will connect to wire switched ON with the key and #2 can wrap right around at the alternator and hook into the big BATT lug.

Did the charging system work properly before. Your post indicates you had a externally regulated alternator running in conjunction with a regulator designed for a generator. This should not have worked. A generator is regulated by switching the field to ground...a alternator is regulated by switching field to voltage.

If you want reliability and ease of installation, a single wire is the ticket in my estimation.

Stuart

I am not sure if it ever worked, I just bought the truck and the wireing is not correct. I am trying to make it right.

I am a little confused on the "three wire unit" my alternator is wired simularly to what you described, jumper wire to BAT. It does have a three wire regulator but from what I can tell it doesn't look like any of the alternator wires go to it. Go figure, it's a mess. I am cutting into the sleeving to find out where all this mess goes.

If i go with the three wire or the one wire can I get rid of the voltage regulator and all associated wireing that goes to and from it?

Rcimp,

Yes, you can get rid of all the mess! Any alternator version you choose will have the large gauge BATT wire. With the single wire unit, that's it! With the three wire unit, there are two more wires..the ones utilizing the DA plug. If you wrap #2 around at the alternator, the only wire left to deal with is the small #1 'excitation' wire.

You can make the connection from alternator BATT to the existing BAT wire on the voltage regulator on the firewall. If this wiring is intact and proper, this should route power through the ammeter and to the battery.

The #1 wire needs to see voltage when the truck is running. I don't know what you had before, or what worked before, so all I will say is that you need to connect this #1 wire to some other wire that springs to life when you turn the key to ON.

This rig has already been converted to 12 volts in all the other areas, correct...coil, lamps, gauges etc. Keep at it!

Stuart

Rcimp,

After some digging, it appears there is no wiring associated with the old generator voltage regulator attached to the firewall that provides a key switched source of power for your #1 DA plug wire. If the rig has been converted to 12 volts, some folks pick this switched power off the coil...it's easy to get to.

If you do this, run-on can be an issue after the key is turned OFF. A simple in-line diode can cure this problem. If you do this, you will want a connection that provide a full 12 volts. This means if a ballast resistor is utilized, the connection must be BEFORE the resistor.


Stuart

Stuart, I was told that my alternator was internally regulated, the DA plugs are on the back not on top. I was told all externally regulated alternators had screw terminals for all connections and the internally regulated alternators had the two flat plugs. This explains the jumper from one of those connections to the BAT side of the alternator, just like you suggested. I haven't looked yet but I bet the other wire goes to a switched 12v. If that is the case then I am ripping out the regulator.

I just installed a 12V fuel gauge, the oil and temp gauges are mechanical so no worrys there and the ammeter should work regardless of voltage. I have 12V headlights and parking lights and I have a new 12v electric windshield wiper motor conversion kit and I have a new 12v fuel tank sender just in case the old one doesn't work. The coil has a resistor before it. I may switch it to a 12v unit later on

Rcimp,

Something is rotten in Allen! To the casual observer, SI alternators and externally regulated alternators look the same. No alternator we have discussed has screw terminals.

The DA plug configuration is the clue. SI (internal voltage regulator) alternator terminals look like this --. External regulator versions look like this II. No screws..both DA plugs!

The resistor before coil is called a ballast resistor. Its function is to bring system voltage from 12 volts to somewhere between 7 and 9 volts. This reduces the voltage to the points and extends their life. The coil still must be a 12 volt item.

Someone gave you incorrect info on the alternator...I would find someone else to consult. The pin configuration, and location are 99.99% positive IDs. Someone might pop in here and tell us that a DA plug on the BACK of the case...like yours, is also a clue that the alternator is externally regulated. Don't give up.

Stuart

Ok, based on my research your statement on the alternators is correct and I was mis-informed at NAPA. I feel very comfotable now replacing my existing external regulated alternator with the DA tabs like this II with an internally regulated alternator with DA tabs like this --. I will also get rid of the voltage regulator on the firewall. Yoohoo!! Thanks for all of your help Stuart.

Rcimp

It seems to me that it must be an internally regulated alternator and the generator's regulator is just being used as a terminal block to get to the ammeter and is not being used as a regulator. The "R" wire could be the remote sense line and hooking it to the Batt terminal is SOP.

Baldy,

Because of the pin orientation and pin location, I think this unit is an older style external type. My poor notes show that on this style alternator, 'R' terminal is switched voltage and 'F' terminal would be the sense circuit.

I have a SI style in front of me...the case is marked near the DA terminals 1/R--2/F. Why they double mark these things I don't know, but those markings would correspond to my guess on wire function.

EDIT. I think I'm wrong on those terminals. After looking at a few manuals, it seems that Baldy was probably correct. 'R' would be sense and 'F' is switched.

Stuart