One wire alternator wiring?

Ron in AZ

Ron in AZ

Senior Member
Can I hook up my one wire alternator right to the battery or do I need to have it go through the ign switch? Or a diode?
Will it run the battery down when it is not running?
I checked between the battery and the alternator with my volt meter and it shows 13.5 Volts... I assume it would run the battery down... or not. It is a brand new alt. and is in working order ... I know that much.
I does not spark when you touch the wire to the battery, but shows voltage with the meter between the two.
Any help on this simple job would be great .....
(I did look up other threads on this but all I found was topics with a alt. with a regulator, not a one wire alt.)
Thank you from the electricialy challenged...
Ron in AZ
 
I have run one wire alternators in several cars,I always do two things I get two cables like Fords use from the solenoid to the starter which are usually 4 or 6 gauge at most parts houses and run one from the alternator to the POS+ battery post, I run the other cable from the alternator bracket to frame ground.Never had any issues,a lot of times in the course of a build people forget to run grounds,I also run another ground cable from an intake bolt to the firewall.
 
There has to be some draw to start the alternator working, in the original application (GM cars) they used 3 wires, 1 to batt, 1 for voltage sensing, 1 for the ignition through a light bulb ---that little electric through the bulb started the regulator working, when you convert to 1 wire that electric is taken all the time so the alt is ready to charge ---perhaps there are versions of the regulator that use less ---this is where a generator is superior, it keeps a little magnetism, is self starting, even with a totally dead battery, spin it up and it will charge , the alternator needs some outside electric to start itself.

For long term storage unhook the battery.
The alternator "1 wire" can be hooked up to the wire that originally went to the cutout.
 
I've run a 1 wire alt on a 302 Y block with no problems. Ran the "HOT" wire direct to the battery side of the solenoid. It is a good idea to run a ground wire from the alt to the frame. I use welding cable for all hookups.

There is a milliamp draw from the bat to the alt diode but a fully charged battery should not discharge for months.

When I leave it for more that a few weeks I disconnect the bat just to be safe.
 
Should there not be a fuse between alternator and battery source, fuse size depending on the alternator output amps. Zeke
 
Kurt in NJ said:
There has to be some draw to start the alternator working, in the original application (GM cars) they used 3 wires, 1 to batt, 1 for voltage sensing, 1 for the ignition through a light bulb ---that little electric through the bulb started the regulator working, when you convert to 1 wire that electric is taken all the time so the alt is ready to charge ---perhaps there are versions of the regulator that use less ---this is where a generator is superior, it keeps a little magnetism, is self starting, even with a totally dead battery, spin it up and it will charge , the alternator needs some outside electric to start itself.
Click to expand...

OK: Is the wire to the ignition thru a bulb the small green wire? Would that be the indicator light on the instrument panel that shows that the alternator isn't charging? And, can the other heavy pink wire be connected to the battery as well? Does it have to be such a heavy wire? (I recently harvested some "regulatorless" altenators along with much of one of the harnesses and was wondering what is required to get one to work.) Thanks!!
 
Jeff, I do have the ground cables that came in place with the truck(this is on a 47' Ford COE) from the engine to the body but after Tom said use one "to the frame " I looked and I may need one there also ...Thx
and Kurt, it sounds like I should hook up the indacator light also.. would be a great idea any way , to know if the thing is working ... before I end up with a dead battery if it is not...!
Thx Ron
Would it matter if the wire goes to the battery instead of the solenoid ? in a COE the battery is easer and shorter to get a wire to instead of the solenoid because the solenoid is on the frame way below everything.
No room for anything on this truck..."COE"= it meens stacked on top of everything!!!
 
fusible links, cook, so I am not for using them. Autowire and some others make a fuse or breaker that can be used.
 
The modern 1- and 3-wire 10-si and 12-si alternators and their clones are virtually the same. The 3-wire can be easily converted to a 1-wire by simply connecting the voltage sensing terminal #2 to the main BAT terminal with a short thin wire. The ignition switched exciter terminal #1 isn't used. Because this exciter terminal isn't used, 1-wire alternators must rely on self-excitation from a small amount of residual magnetism in their iron cores. That's why 1-wires often won't start charging until rpms are bumped a bit.

3-wire setups are preferred since voltage drops at points remote from the battery are automatically compensated for and engine revving isn't needed to start charging.

Jack E/NJ
 
Thanks Jack! So, I should be able to connect the #1 terminal (thin green wire) to the ignition switch (or ballast resistor side away from the coil?) And, the #2 terminal directly to the "output" terminal.
 
PeteVS>>>So, I should be able to connect the #1 terminal (thin green wire) to the ignition switch (or ballast resistor side away from the coil?) And, the #2 terminal directly to the "output" terminal. >>>


Put a bulb or idiot light in series with the wire connecting the #1 terminal to the ignition switch as per the wiring diagram below. Fuse is optional.

Yes, the #2 terminal can be connected directly to the output or BATT terminal. Or you can connect it to a more remote location to compensate for voltage drop at that location. Your choice.

Jack E/NJ
 

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Thanks Jack. Now, I can get that alternator to do something other than act as an idler pulley for the water pump. When I was younger, I worked for my neighbor in his ignition shop rebuilding starters and generators. Alternators had just come out (1960 on Chrysler products) but I was off to a real job before they started to need servicing. The older 3 wire alternator makes sense to me, but this other stuff is just too new fangled for someone with my skills set.
 
Hi guys I have a 31ford roadster I installed a 1wire alternator do you have to remove the cutout I need a wireing diagram that I can understand thank you for any help
 
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