Re: Whitch Alternator?

Thu Oct 24, 2013 7:04 am

No one on this forum has argued that the one-wire significantly discharges the battery during times of disuse. As far as I know, the one-wire depends on residual magnetism for exciting and after long periods of disuse may require "flashing" to begin the charging process. As far as I know the one-wire does not place ANY draw on the battery during times of disuse.
With that out of the way, the one-wire typically requires higher RPM to begin charging. I have not used one of those on a Cub, but on a conversion another tractor (that I do not own) with engine RPM slightly lower than the Cub, the engine must be brought nearly to full throttle to begin charging with the one-wire. And that is with a smaller-than-original pulley on the alternator. I use a Browning cast iron pulley, typically 2 1/2" diameter of proper width for the belt, bore it for the alternator shaft. A smaller pulley on the alternator spins the alternator faster. But the disadvantage is that the belt life is reduced, particularly with wider belts. Flexing the belt around a smaller pulley creates more heat within the belt. The short belt on the Cub means that the belt has little opportunity to cool between the flexing cycles.
Weighing all the factors involved, I use the smallest practical pulley on the alternators for conversions that I do.

Re: Whitch Alternator?

Thu Oct 24, 2013 7:18 am

"I am looking at buying this alternator: ... alternator

which really has only one connection terminal. Does a one-wire alternator need a diode? (I don't think so). Where/how is the ignition switch connected? (that's my basic question here) The 3-wire alternator wiring diagrams leave me with just enough confusion that I don't want to extrapolate to the 1-wire case without some confirmation."

For that one, using the ammeter, the one wire goes directly to the ammeter. The ignition switch is not involved in the charging system for that alternator. No external diode needed.
Assuming that the alternator offered is all that it claims to be, that is great a price. 20 years ago, most of the one-wire units were that much or more, some of them were over $100.
When I do a conversion, sometimes my first attempt with the mount and the tensioning brace does not work as planned. Sometimes it takes 3 tries for the desired results. When it does mount as desired, I then make an extra set of the needed parts, tag and put on the shelf in case conversion of another similar/identical tractor should happen later. Mostly it does not happen.
Last edited by Bus Driver on Thu Oct 24, 2013 12:23 pm, edited 1 time in total.

Re: Whitch Alternator?

Thu Oct 24, 2013 9:25 am

All the one-wire conversions I have done have been for others, not presently available for me to test. All worked out well.
Searching the internet turns up all kinds of opinions and "test" results for the standby current draw of one-wire alternators. The test I would do involves (vehicle not running) removing the wire from the alternator, placing a voltmeter between the now-vacant alternator terminal and the wire. A voltage reading indicates a current draw. No voltage indicates no current draw. That is the simplest initial test. Be sure not to short the wire to some part of the alternator or the engine-- that could get exciting!
Last edited by Bus Driver on Thu Oct 24, 2013 12:24 pm, edited 1 time in total.

Re: Whitch Alternator?

Thu Oct 24, 2013 9:57 am

Bus Driver, the test you propose is good to know but let me explain how to measure current. If you remove the wire and insert a meter to measure current, set the meter to read current not voltage. When you do it your way your just measuring the battery voltage. If you just set a battery on your workbench and place a voltmeter across it, you'll get a reading, but there is no current flowing. If you want to measure the voltage on the terminal, you don't need to remove the wire, just set the meter to volts and one lead on the terminal and the other lead to chassis ground. But that won't tell you if there is current flowing in the wire. You have to break the circuit and insert your meter set to "DC current". Another way to measure the current with a voltmeter is to insert a small value resistor(say 10 ohms) in the wire and reconnect. Then measure the voltage across the resistor and use Ohm's Law to calculate the current, I=V/R. If you inserted a 10 ohm resistor in the wire and measured .1 volts across it, there is .01 Amps (10 millamps) flowing in the wire.

Re: Whitch Alternator?

Thu Oct 24, 2013 10:32 am

My test method is the most sensitive one available. If the most minute current draw (smallest imaginable) is occurring, the VOLTMETER will show a reading when bridging between the alternator terminal and the conductor. Checking for current with an ammeter would be the follow up test.
But the test with the ammeter would be of limited usefulness. If it is high enough to cause unacceptably rapid battery discharge, the only choices are to repair/replace the alternator or to place a switch in the one-wire conductor which would be operated manually with each use of the tractor. And that switch would of necessity be of higher amperage capacity.
If one uses a test light or an ammeter for the initial test-- and the current draw is too small for the meter range or to light the lamp being used, one would mistakenly think that no draw is occurring.
My previous post is correct for the intended purpose.
Last edited by Bus Driver on Thu Oct 24, 2013 12:48 pm, edited 1 time in total.

Re: Whitch Alternator?

Thu Oct 24, 2013 12:42 pm

Going back to part of the post above: "When you do it your way your just measuring the battery voltage. If you just set a battery on your workbench and place a voltmeter across it, you'll get a reading, but there is no current flowing."
Actually there is a current flowing in that instance-- the current that is creating the meter reading. Leaving that voltmeter connected as described will eventually discharge the battery.
The analog meters used for Cub instrumentation are all milliammeters-- an ammeter with full scale reading of 1 milliampere -- 1/1000 ampere. If the proper resister is placed in parallel (shunt) with that meter movement and the meter face is appropriately scaled, it is used as an ammeter. That parallel resistance (shunt) is relatively low ohms. If a high resistance is placed in series with the meter movement and the dial face is appropriately scaled, it is used as a voltmeter. So either meter actually reads current. But as they are setup for use, a very small current causes a greater movement of the meter pointer on the voltmeter than does the same current on the ammeter. Thus the voltmeter is the more sensitive in the use I proposed.
This link offers some explanation.

Re: Whitch Alternator?

Thu Oct 24, 2013 4:09 pm

Oh no, Now it'll be a dreaded Paint Thread....Valspar or Majic ?????? :lol: :lol:

Knowning that it may spur a multi page debacle on pigment content, hardner, dry times and forms of application.....i still may do the unimaginable. I may use a foam brush and apply some Rustoleum Harvester Red. :shock: Gasp! :shock:

All in fun.....of course. :beer:

Re: Which Alternator?

Thu Oct 24, 2013 4:30 pm

Maybe a long discussion on paint and pigment and hardness and maybe a long discussion on how to use a voltmeter and ammeter.
Bus Driver, I did the test you describe using my Simpson 260 and measure 2.2 volts on the 10 VDC scale. How much current is flowing? The Simpson 260 meter movement is 20,000 ohms/volt.
Last edited by Gerry Powell on Thu Oct 24, 2013 6:11 pm, edited 2 times in total.

Re: Whitch Alternator?

Thu Oct 24, 2013 4:56 pm

Just finished rebuilding an old SI that I had....Converted it to a one wire, by putting in a new self exciting regulator thereby making it self exciting also...New brushes also..Put it in 57 lo boy and ran a wire from the bat terminal on the alternator to the starter...Then from the starter to the ignition switch...Then from the other side of the ignition switch to the 12 volt no external reisistance needed coil( previously installed)...Hooked a voltmeter from the hot side of the switch when the switch is on and grounded it to the dash (took the place of the ammeter)...Works fine and it took me less time than to read this post.... :lol: :lol: Dave

Re: Whitch Alternator?

Thu Oct 24, 2013 5:49 pm

Bus Driver, If you use the NAPA alt. that I have recommended a 100 times, it will charge at a low speed, it also cuts back as it should. You do not need to rev up the engine. I do not know about other one wire alternators.

Re: Whitch Alternator?

Thu Oct 24, 2013 5:51 pm

I have a how to post in the how to forum that will explain how it is wired.

Re: Whitch Alternator?

Thu Oct 24, 2013 6:11 pm

Boss Hog wrote:I am wondering why some want to use the Hitachi and not the Delco [ the delco was standard on the late 75 -79 longstripe cubs ]
It fit as it should , cost is $50 or so so that is not a factor. and it looks American :lol:

Boss, You told me how to wire this alternator about 10 years ago, but tell me what kind it is? Thanks Ted Image

Re: Whitch Alternator?

Fri Oct 25, 2013 5:10 pm

what Bus Driver is saying (in another way, and not to belabor the point) is that by connecting the voltmeter between the alt wire and the alt terminal with the engine off, any voltage on the meter indicates leakage because it should read zero. reason being that the neg lead of the meter has some path to ground. it is sensitive, and a good test. but it does not tell you how much..just that its leaking. a good simpson set on milliamps will do it too, but most cub guys don't have one... and aren't electrical engineers as some of are.

I like to test

Re: Whitch Alternator?

Fri Oct 25, 2013 5:25 pm

a bit of trivia.. what was the first American automobile to use an alternator? it was my first car, not that that info helps anyone.

1960 Plymouth Valient 173 cu inch, 3 speed on floor (actually under the seat) 27 MPG average NOT a chick magnet!!!!

Re: Whitch Alternator?

Fri Oct 25, 2013 6:33 pm

That is correct, Art, and thank you for posting that it is understood. While not everyone understood or appreciated the post, it was intended to help those who might wish to do such a test. And if any current is flowing, the old-type analog voltmeter, based on the D'Arsonval galvanometer, which some Cubbers have, will show some needle movement. I find that type meter to be the most useful for ordinary testing on tractor electrical systems.
Perhaps someone was helped and, for certain, no one was harmed.

Most often, I use a Hoyt AGB-1. Prices for these have skyrocketed in recent years. If you want one, search for best price. A photo at this website. ... ter.pdfest