1976 L48 auto. Changing to a 100 amp 1 wire alternator. I understand running 6 ga wire thru a fuse to starter. The 76 wiring diagram shows red batt wire connecting to numerous other items. Do I need to reattach it to batt terminal along with new wire to starter? Thanks.

 

Just sayin- one wire sounds easy- but often causes more problems. It doesn't have a dedicated way of measuring voltage and adjusting the current output-and often have to rev the engine above idle to excite the alternator to charge.

You need to fuse at -or as close as possible to the starter . If you connect the charge wire to the starter terminal and then fuse at the alternator- the whole length of the
new charge wire will be unprotected with over 700A of current from the battery - a serious fire hazard.

You need to reconnect the wires at the starter terminal- but do not reconnect the factory charge wire to the new alternator. As that wire is not designed to handle the extra current from the new alternator- nor protected-another fire hazard.

 

I recommend against One Wire Alts.......as Richard mentioned, they have one supply voltage and do not charge at idle.......my last two big engine installs (69' Vette and 56' Bel Air) both customers had a one wire alt in the trunk and I wouldn't use it as a One wire......on both cars i wired it as a three wire.....this is important on cars with heavy draw electric fans......in traffic, your battery will eventually die.......
Jeg's sold a One wire deal that they claimed charged at idle but you can't find it anymore....probably because it didn't LOL.

Jebby

 

Let me just add to the above very correct information.
really good higher amp 3 wire alternators are actually harder to find. However, with the addition of one very inexpensive diode a 1 wire alternator can be converted to 3 wire operation. And they work great!
the aftermarket even sells a pluginplay pigtail with a diode in it just for this.

 

I'm Wondering what brand One wires you all have had or first hand knowledge that failed? I would like to know what brand to stay away from or be aware of. I've installed dozens of one wires with the appropriate fusible link for the power supply ga chosen. I have one in my 67 for going on two years. I use Power master and Tuff. If I need the indicator to function on car equipped I pull the rubber cap of and insert a connector with wiring.

 

I had a Summit brand 100 amp one wire drop the regulator a few years back. A new regulator and it was fine again. But it really ruined my day when it died. I was on a club run and suddenly had no charging system at all. Got it home with help from club members who would stop, hook up jumper cables to my car. Charge up my battery for 5 minutes or so, then hit the road again. Leap frogged all the way home.
Now a days I'm running a 140 amp tuff stuff 1 wire converted to 3 wire operation. (HUGE voltage improvement at idle with fans running). was on a club run and I noticed my volt gauge drop. About a volt and a half. Fans where not running. Turned off the air-con. Was day time so wasn't a huge issue. Figured straight away it dropped a diode knocking my output to 2/3rd's.
sure enough, dissassembled the diode that evening. I know your not supposed to. Found one diode had unsoldered itself. Poor soldering job. Re soldered the contact. Assembled the diode tree and alternator, worked fine again. I did order and install a new diode.

 

Used a one wire on my brothers 68 and used it on several 6 volt to 12 volt tractor conversions. Never had an issue and it’s been 20+ years on some of the tractors a 5+ on the Corvette which has dual Spal fans.

The issue IMO is due to a couple of things.
1. Junk Chinese regulators whether it be one or three wire. Of the 6 or so conversions I’ve done 2 of the alternators were dead out of the box.
2. Whether it be a 1 wire or 3 wire there is a certain shaft speed where the alternator/regulator needs to be to operate. 3 wire regulators do tend to excite easier but once they are going they are good until you shut it down. A couple of tractors don’t excite until about 1/2 throttle but you give them a quick blip and they charge from that point onward.

 

Can you raise the amp output by changing the voltage regulator and bridge rectifier, or is the rotor and stator different?

 

Thats to bad seems as though you have been through the mill. Your experience from days gone by,.required repairing alternators not replacing paid off.

 

Just saying- no OEM manufacturer uses a one wire alternator- and they are illegal on small planes.
I can eat with just a fork- but adding spoon and knife works MUCH better!!!..


On a 3-wire alternator- an old trick is to put a diode on the voltage sense wire- it'll see about a volt less- and make the alternator think it needs to work harder- giving slight increase (~.5V) in voltage.
.
Another trick is to run a small pulley -At idle the alt will spin faster- and be capable of more current- really when you need it most - at idle.

As far as increasing the output on the Alternator- bigger rotor and stator (I'm using one with flat wound wire) - then the rectifier needs to be able to handle the extra current.

I'm running an external rectifier with a cooling fan. Plus a small pulley on built small case Denso flat wound wire alternator- capable of over 90A at idle

 

A diode is basically a one way valve. Adding one will not trick anything. Just keeps the voltage from going backwards.
we add a diode when converting a one wire alternator to 3 wire operation to prevent back feed down the exciter wire.
Which will actually keep your engine running on key off without it.
The guts of a one wire alternator are different in this way. A one wire alternator only senses voltage at it's own source. A 3 wire alternator senses voltage in the harness well downstream of the regulator. So when load like electric fans are applied, the sense wire does just that, it senses the drop in voltage and kicks up the output to compensate.
I have run both systems. And it's definitely worth more than half a volt.
Also the 3 wire alternator doesn't need revs to get started. That's what the exciter wire is all about.

 

I agree that a one wire alternator never was used in an automotive factory application and I assumed it was borrowed from the marine industry for the automotive aftermarket.

 

A diode will drop the FORWARD voltage around .5V. The alternator will "think" the voltage is lower and will charge at a higher rate.
I spent a few years in the Car Audio industry- it was a trick to keep the voltage up when the current demands were very high.
GM used a similar trick- by sensing the the voltage using a long small wire-with the increased resistance - the alternator sees a lower voltage- and compensates.

Great article from Mad Electrical-

THE UNIQUE PART OF THE CHEVY SYSTEM

It’s a rare occasion when a little resistance at a main wiring circuit is helpful. And it’s also a rare occasion when a system is improved while violating what old institution has been teaching for years. (And sometimes delightful too, part of the fun with Hot Rodding has always been sort rebel related. Ha!)

Leading authorities have often told us not to accept more than 0.4volts difference between the alternator and the battery! In fact DELCO REMY published engineering data for wiring the components they built, instructing maximum of 0.5volts difference between the alternator and battery, with the alternator operating at maximum output.

Also on the same engineering data sheet, DELCO REMY published recommendation for minimum cable gauge sizes per feet of cable between the alternator and the battery, and included various alternator output ratings in the chart. For alternator output ratings between 50 and 65 amps, the chart begins with 8gauge for total cable length at 4 to 7feet. And by the time the total cable length grows to ’69 Camaro dimensions, DELCO recommends 4gauge cable! In this author’s many years of workshop experience, an original GM built passenger car with larger than 10gauge wire for 63amp alternators has never been encountered.

The instruction was intended to help with the wiring job to be done by Chevy (and also other carmakers and companies who might install DELCO REMY alternators). The engineering data was published as a guideline to insure proper system operation when using the parts built by DELCO REMY. Sometimes these guidelines are intended as a cover all blanket, work in all situations, and always get the job done installation method. (Guidelines are intended to keep people out of trouble.) In other words the provided recommendations are guidelines, but not intended as solid, rigid, “never-to-be-an-exception,” rule.

If cars would have been entirely built using all minimum engineering recommendations for copper cable gauge sizes, then these cars would be hauling around a few hundred pounds of very expensive copper cable. Since it was not practical to install so much heavy copper cable on the millions of cars built, Chevy engineering provided a practical exception to the rule.

At least one thing about wiring for this Chevy alternator system is very unusual, excessive voltage drop between the alternator and battery will occur with normal system function—and yet the electrical system worked fine. The battery charged perfectly and electrical system performance was not compromised in the least bit. It was a feat accomplished by the wiring system layout. Not only that, but it was a forgiving system that was more gentle to batteries and alternators in the event of recharging a battery while driving!

No doubt those “rebel with a cause Chevy engineers” who came up with this system knew exactly what they were doing. Truly the Chevy wiring system was unique. The design caused the voltage regulator to take voltage reading from the main power distribution hub (the splice). The heavy cable and minimum voltage drop recommendations from DELCO would have worked, even without special attention to where the voltage regulator would take voltage level reading.

Mounting location of components caused long wire length at the alternator output circuit, and also at the battery charging circuit. These two wires deserve the most attention, in this system. Long lengths at these two wires give the Chevy system special characteristics. Component locations to be concerned with are the battery, alternator, voltage regulator, and power distribution “splice.” (Please see “THE ORIGINAL CHEVY SYSTEM” diagram above.)

THE ALTERNATOR OUTPUT WIRE (Please refer to “The ORIGINAL CHEVY SYSTEM” diagram.)

When current flow through long wires is a large amount, a “problem” with significant voltage drop will occur. But regarding voltage drop at the long length of “alternator output wire,” the system was self-compensating. The regulator took voltage reading from the splice, which distributed alternator power. (“Voltage-Sensing was not from the alternator or the battery!) The regulator adjusted alternator output as required to maintain proper voltage level at the splice. Therefore a little voltage drop in a long wire from the alternator did not reduce system performance. The alternator did not mind producing power at 15.2volts, which allowed for a 1volt drop in the long wire, to arrive with power at the “splice” at 14.2 volts level.

This part of the system layout did not happen by chance. The voltage sensing wire from the regulator was connected where it would optimize system performance, which let the main hub distribute power at 14.2volts. It was a wiring design created with definite purpose in mind. Thanks to some clear thinkers at Chevy engineering department we were spared some cost, and weight, and bulky cables at the front of these cars!

Of course the system would have worked equally well with 4gauge copper cable connecting the alternator to the horn relay, and 4gauge connecting the alternator to the battery. And then, “voltage sensing” for the regulator could have been connected anywhere in the main system–Or even at the alternator itself (as with the “ONE-WIRE” alternator). But manufacturing the system with so many feet of 4gauge cable would have contributed to higher cost of these cars! And, the system with 4gauge cables would not have performed any better than the Chevy system with only 10gauge wires. (Also see our Tech Section feature on “REMOTE VOLTAGE SENSING.”

 

And I thought I'd read everything from Mad Electrical. But this I had not seen.
And although I do run a very heavy wire from the Alternator to the starter solenoid (Poss battery cable) I can tell you with the most certainly. That converting my one wire 140 amp Tuff Stuff alternator to 3 wire operation made a noticeable difference on my volt gauge at idle when my fans kick on.
Before I converted it over. When my fans kicked on I could easily tell by glancing at my volt gauge. Now I run a idiot light to tell me when the fans are on. The volt guage does move, but it's so slight it takes much more than a glance to see the difference.
So. In my humble opinion. It is definitely worth the cost of a 2 dollar diode (or less in the states). To convert over. And my gen light works like factory again.

 

So, reading your post Richard, and always wanting to learn. At the end was this recommendation on their remote voltage sensing tech pages.
I went to the Mad Electrical site and did just that.
And they have a brilliant article with lots of shots of their guages and a really good write up explaining why the remote sensing system works so much better than a one wire alternator. Basically backing up my experiences.
Many times I have recommended to members of this forum to go to Mad Electrical 's web site and read there tech pages. Looks like they have added a few. Glad I had a look.
And for the record, I will still advise all who will listen to run a 3 wire alternator, or simply convert a one wire to a 3 wire.

 

It wasn't till the mid eighties that GM started putting high amp internally regulated alternators on their cars. Optioned Fiero's had 94 amp equipped. In sixties the alternator was a new charging system design as the need for more current at idle was required (due to electric radiator fans, heated seats etc.) but the tech was not there for what we have today of course. A C6 has a 160 amp alternator wired 4 gauge power supply with an 8 gauge fusible link as an example. Good batteries with excellent reserve capacity were/are a must sitting at idle with all the power consumers on, today its not with the alternators available. The one wire works. Is there a little variation? yes but who cares. Back in the 60's 70's 80's as long as you were at 12.75 vdc in drive with headlights,wipers and blower on medium and the charging system didn't go over 15 volts it was the norm. Richard I'm surprised you didn't go with a water cooled alternator in your hotrod. A unique system for sure.

 

One wire