Sirsmiley9
Well-Known Member
When you install a one wire alternator from what I understand you run one wire straight to the battery, but I just wanted to confirm and ask what you connect the old alternator to voltage regulator wiring too
Installing one wire alternator
- Thread starter Sirsmiley9
- Start date
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Define 1 wire alternator.
Are you saying internally regulated and there is only 1 heavy guage wire from the alternator to the battery,
OR
1 field wire externally regulated alternator with one heavy guage wire to the battery and one lighter guage wire to the regulator
Are you saying internally regulated and there is only 1 heavy guage wire from the alternator to the battery,
OR
1 field wire externally regulated alternator with one heavy guage wire to the battery and one lighter guage wire to the regulator
67Dart273
Well-Known Member
The accepted definition of a "one wire" alternator is that it has a special type of built in regulator and only has 1 wire---the large wire feeding to the battery, and of course ground
I don't particularly care for them for one reason.......you must have a big, oversized charging wire, because that one wire is also the SENSING wire, and with heavy loads, and additionally a low battery, such as after starting, in winter, or dark, running lights, heater, and so on, there can/ will be voltage drop on the charge wire. The voltage at the battery end will be lower than normal
I don't particularly care for them for one reason.......you must have a big, oversized charging wire, because that one wire is also the SENSING wire, and with heavy loads, and additionally a low battery, such as after starting, in winter, or dark, running lights, heater, and so on, there can/ will be voltage drop on the charge wire. The voltage at the battery end will be lower than normal
6PakBee
Well-Known Member
This is one of those love/hate things. Single wire alternators are utter simplicity from a wiring standpoint, one wire to the battery terminal and you're done. Down sides are that typically they take more rpm to begin charging and as 67Dart273 points out, they maintain a specified voltage at the alternator terminal, not at the system level. Some of my friends have used them with some success on cars but I think the level of success is on a case by case basis. I really like them for equipment that typically runs at a relatively constant rpm (generators, agricultural tractors, water pumps, etc.).
Sirsmiley9
Well-Known Member
I believe it is a one wire to the battery, but I didn’t realize there was an addition wire to a ground, but does anyone know what you are supposed to do with the old wiring to the alternator and voltage regulator. I remember seeing something about unplugging them awhile ago, but I closed the tab
67Dart273
Well-Known Member
All you need do is safe the old wires off.
If you are (you didn't say?) working on a 69/ earlier, there is only a "hot" switched wire to the VR (IGN), dark blue, and then the green becomes disconnected at both ends
On a 70/ later system, the connector for the VR pretty much IS safe unless you want to cut it off and hide it, so tape off the blue. The green will no longer go anywhere
At the alternator, the blue field wire is switched 12V so it also needs to be taped/ safed off
If you are (you didn't say?) working on a 69/ earlier, there is only a "hot" switched wire to the VR (IGN), dark blue, and then the green becomes disconnected at both ends
On a 70/ later system, the connector for the VR pretty much IS safe unless you want to cut it off and hide it, so tape off the blue. The green will no longer go anywhere
At the alternator, the blue field wire is switched 12V so it also needs to be taped/ safed off
Simply said, I had 2 field wires on the new harness, green and blue. Connected (green) to the single field tab on the alternator.
I just left the other one disconnected, and it has been charging properly for 2 years now.
I just left the other one disconnected, and it has been charging properly for 2 years now.
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67Dart273
Well-Known Member
You are confusing the issue, or you are confused. That alternator ended up being one field terminal grounded, for the 69/ earlier system. That is not a one-wire system. Further, replacement alternators are a real shot in the dark, as some that SHOULD be isolated field were incorrectly grounded by the "rebuilder." So, it's a can of worms
Yes.
I confused the issue.
I confused the issue.
67Dart273
Well-Known Member
I can certainly understand. "Slang" terms sometimes are not clear, and not clear "across the country." I remember in Navy boot camp, someone got to taking about "gears" In my small town, "tall gears" meant high speed, lo ratio rear gear. Whoever this was said where he's from it meant a high ratio, low speed.
You need to describe exactly what alternator you have. Whatever you know about it - Is it a Chrysler? Who you bought it from? Or a photo?
As you can see from the discussion, none of us on this side of the screen really know what you have, why you bought it and what has been done to the car.
An alternator works by spinning an electromagnet. The spinning magnetic field induces electrons to move in the surrounding static windings.
That electromagnetic needs power to operate, and something to control that power. That something is the regulator.
The illustration shows the spinning electromagnet and a regulator controlling the feed. (The second brush is grounded to the alternator housing.)
(1970s regulators (the ones with the triangular plug in connector) are connected to the second brush with a wire.)
The idea behind the original alternator wiring is this: Power generated by the alternator goes to run the car, then any left over is available to recharge the battery.
Typical '60s alternator wiring
One wire alternators ( one and only one connection to alternator other than case ground) have been around since the 70s and have been on millions of cars. They emerged when it became practical to miniaturize electronics enough to put the regulator inside the alternator. Custom car builders love them since wiring is very simple.
To me, there is only one downside to one wire alternators that are used on cars that are not driven everyday. Since the alternator has only one wire that is connected directly the battery, it can’t be “turned off“. This means that it is pulling a small amount of current all the time, about 75 micro amps (less than about a tenth of a milliamp) on GM alternators that I am familiar with. This will drain the battery in about a month or so, based on data I observed with a boat I had with one. If you don’t drive the car regularly, you need to unhook the battery or use a battery tender.
To me, there is only one downside to one wire alternators that are used on cars that are not driven everyday. Since the alternator has only one wire that is connected directly the battery, it can’t be “turned off“. This means that it is pulling a small amount of current all the time, about 75 micro amps (less than about a tenth of a milliamp) on GM alternators that I am familiar with. This will drain the battery in about a month or so, based on data I observed with a boat I had with one. If you don’t drive the car regularly, you need to unhook the battery or use a battery tender.
67Dart273
Well-Known Member
I would dispute that. My impression is that they are mostly found on industrial and some trucks. Ford/GM/Chrysler certainly did not use them, or not much. The "usual" Toyota/ Denso alternator is not "one wire."
Again, for me one big downer is that they require a HUGE oversize charge wire to properly provide well regulated voltage at the battery end. This is even more critical in a trunk mount situation. Frankly, I see NO ADVANTAGE at all to a "one wire" vs any setup with a separate "sense" wire which adds "voltage accuracy" to the installation.
I do see the attraction (simplicity) and in fact have one on my old (6v-12V) Farmall.
As I recall GM had alternators with built in regulators for about 30 years from the 80s to 2000s
yellow rose
Overnight Sensation
Ok, I need to upgrade my alternator so what alternator do you recommend? I don’t really want a 1 wire unit. I’d rather have on the just plugs into my wiring.
I think I need a 90 amp unit.
TIA
YR
67Dart273
Well-Known Member
Well I believe incorrect. My 04 GMC is not one wire, nor was the 95 Olds I sold. They may LOOK like a one wire unit, but you can not tell on the older frames by looking. The thing that makes the older Delcos a "one wire" is the regulator.
This one is not "one wire" but you can not tell by looking. The one on my Farmall looks exactly the same
Can you cite some specific models?
Yes GM introduced the internally regulated SI alternating current 'Generators' to replace the externally regulated DN models.
But they were not 'one wire'. They could be wired different ways but production automobiles and trucks have an exciter (1) tied to the igniton circuit for initiating the field and a sensing wire (2) to measure the system voltage at where ever the designer decided was most important.
Not going to discuss the wiring further here as its confusing enough and this thread has already gone off track before the OP has had a chance to respond...
LOL
Sirsmiley9
Well-Known Member
Sorry for not mentioning the type of alternator its a 75 amp powermaster chrysler square back One wire internally regulated alternator.
I think I was getting internal regulators and wiring mixed up. My bad.
Pete in NH
Well-Known Member
HI,
Be careful with big alternators and stock wiring and ammeters. The bulk head connector contacts could barely handle 35 amps when new and the ammeters were good for about 40 amps. 90 amps alternators can get you into trouble without some wiring upgrades.
Be careful with big alternators and stock wiring and ammeters. The bulk head connector contacts could barely handle 35 amps when new and the ammeters were good for about 40 amps. 90 amps alternators can get you into trouble without some wiring upgrades.
OK. So the next questions are why? Usually people choose one of these for a particular reason or someone told them is was a good idea. If you are in the latter catagory, my recommendation is to exchange or return it.
Ratings: I've gone on about ratings games in other threads, but the key things are the following.
1. Power available at low rpm is significantly less than the rating, and higher rated alternators do not always produce more power at idle speeds. Sometimes less.
2. Actual power output depends on the demand, not the availability.
---Let me explain that.
To run a basic car with points or electronic ignition electric power is needed for the ignition and to power the alternator. That's around 4 amps at 14 Volts. (The power then is 4x14= 56 Watts). With the alternator regulated to produce power at 14 Volts, the alternator output will be 4 amps. The current flowing out will be 4 amps whether the alternator is capable of producing 4, 40, or 140 amps at idle.
Turning on the lights, stepping the brake (brake lights), turning on the wipers of course increase that demand. But the power needs are still pretty modest. Depending on the car options, year, the bulbs etc, 20 to 30 amps is really all that's needed to run things.
The one item I have not mentioned yet is that can draw a lot of current is a discharged battery. This is a variable load. As a battery recharges, it draws less and less current. Fully recharged, the battery draws no current.
Connecting direct to the battery:
If you connect this one wire alternator output direct to the battery, and no other changes, all of the power to run the car (except the alternator's field) will go to the battery first, then through multiple connections, through the ammeter and finally to the main splice. (assuming this isn't a '76 or other less typical wiring)
Each connection and the distances, especially in a hot engine bay, will all contribute to resistance to flow.
Besides the extra distance and connections there will be some other issues to be aware of.
1 The ammeter will show discharge all the time.
2 The original battery output wire (R6) and field power wire(s) need to be removed or otherwise made so they can not ever touch ground.
3 A short in the alternator wiring will cause the battery to discharge until the wiring burns up. The bigger the wire - the longer it will take to burn.
mopardude318
Well-Known Member
I’m reviving this thread because I need a little help. Working on a ‘1974 Dodge W200 truck.
I’m installing an internally regulated Denso 60 amp 3 wire unit. I’m kinda following 2 sets of instructions.
I have a 6ga wire from the alt output going to a fuse as you can see on the firewall, and from there I’ll be going to the starter relay battery lug. I think ANDY AR Engineering’s instructions call this a “Shunt” to keep the whole load going into the firewall on the original black 10ga alternator wire to bulkhead.
Now can I still place this same 10ga black wire on the output stud of the new alternator along side the other heavy 6ga? (this one goes through the bulkhead)
(this is the old alternator output wire going to bulkhead, which then connects to many things like ignition switch, high & low beams, ammeter, fuse panel) Because of all this I thought it would be a good idea to also use this wire. ?
I’m installing an internally regulated Denso 60 amp 3 wire unit. I’m kinda following 2 sets of instructions.
I have a 6ga wire from the alt output going to a fuse as you can see on the firewall, and from there I’ll be going to the starter relay battery lug. I think ANDY AR Engineering’s instructions call this a “Shunt” to keep the whole load going into the firewall on the original black 10ga alternator wire to bulkhead.
Now can I still place this same 10ga black wire on the output stud of the new alternator along side the other heavy 6ga? (this one goes through the bulkhead)
(this is the old alternator output wire going to bulkhead, which then connects to many things like ignition switch, high & low beams, ammeter, fuse panel) Because of all this I thought it would be a good idea to also use this wire. ?
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I think the term shunt in the instructions is misleading.
Basically what you are doing is bypassing the ammeter.
You still need all the existing OEM wiring hooked up as it was originally. (Except the voltage regulator and field related wires)
The benefit to doing this is now the loads of the car (main splice, etc) are shared by two spade connectors thru the bulkhead connector vs just 1.
Basically what you are doing is bypassing the ammeter.
You still need all the existing OEM wiring hooked up as it was originally. (Except the voltage regulator and field related wires)
The benefit to doing this is now the loads of the car (main splice, etc) are shared by two spade connectors thru the bulkhead connector vs just 1.
mopardude318
Well-Known Member
Okay I'm not there yet but yes, I'll be removing the external voltage regulator/plug. The green wire that goes from the plug to the ALT is easy, the red wire from plug goes into the big splice. I assume I can just cut that at the splice? (Then that little harness will be free)
Going back to my original question, I will have the ammeter reconfigured to a voltmeter. But is it still good to run the original black 10ga wire to the ALT output stud as well?
In my opinion yes.
As to the VR wiring can't help you there as I'm versed in electro/mechanical (67) not electronic.
Just be sure you don't inadvertantly remove the power to the ignition.
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