A poser

Okay I have been thinking this over and I think it is doable if someone has electrical expertise. I would like to convert a 6 volt system to a 12 volt with a one wire alternator. I am thinking a resistor at the battery terminal on the + side and then feeding everything 6 volt from there. Just run 12 v from the alt to battery. What do you all think? How big a resistor would I need if it is possible?

NOT that simple, "cuz the voltage dropped across a resistor is proportional to the current flowing through it.

Bob is correct. Not a good plan for several reasons. The only thing needed to make the change correctly are new light bulbs and an ignition resistor to drop the 12v to 6 for the coil.
The starter will be fine as is.
One wire alternators are technically on pilot draw all the time. Thus if you do not run the tractor for a few weeks, it might be dead. A three wire system as outlined by Bob M in the archives is better. Search for Bob M Diagrams. Jim

ditto what bob said.

your mission is nigh impossible.

you can run a 12v 1 wire alt and 12v battery. and run a 6v points based ignition with use of the oe coil and a ballast resistor OR.. simply switch to a 12v coil.. if it uses a common round coil.. a napa ic14sb will work.

that leaves lamps and cigar lighters. lamps.. most old style lamp sizes have a 12v counterpart. if not. wire the 6v lamps in series. not desireable.. but works.

for the cigar lighter.. 2 options. run it like it is and just be carefull to not leave it engaged too long.. or get a ceramic resistor of about 1 ohms and stick inline.

soundguy

(quoted from post at 10:41:54 07/03/13) The starter will be fine as is.
. Jim

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The starter will work, but not necessarily "... be fine as is". I had a 6v. on my converted to 12v. 240U and the problem with it was that it would spin the starter too fast and sometimes the drive would not engage the ring gear. When the starter finally quit all together, I took it to the local auto-electric shop and in addition to repairing it, he changed the 12v. field coil to 6v. It made [u:4e52ac2b1b]all the difference in the world[/u:4e52ac2b1b] how easy it starts. I believe changing the coil added about $70 to the bill, and well worth it.

x4 on what Bob said.

Resistor only works on the coil because the coil is a small constant load.

If you put each separate item on its own resistor, then you could make it work. On a letter series IH, the only other thing on 6V is the lights. Bulbs are much cheaper, easier to replace, and do not add extra complications into the system.

The only way to make it work with one device is with a very large and expensive voltage regulator, and if it fails you are dead in the water wherever you sit. Changing bulbs is still simpler and cheaper, not to mention more reliable.

no the conversion is not impossible give me a day or two and
I will look up my diagram for 12 volt 6 volt and see if I can sen

The new style one wire alternators do not pull down your battery to speak of. I have a W9 and a 650 that both one wire set up. They have set as long as 6 months with out any noticeable drop in battery power.

(quoted from post at 09:55:26 07/03/13) no the conversion is not impossible give me a day or two and
I will look up my diagram for 12 volt 6 volt and see if I can sen

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A 6V to 12V conversion is not impossible, but the way he wants to do it is:

He wants to keep everything 6V, and install one big resistor to "convert" the 12V from the battery/alternator to 6V for the whole tractor.

Ohm's Law, my friend. It won't work.

He'd need resistors on each individual item, custom sized for the load and current. If the item has a variable current, then the resistor idea won't work at all.

Not practical to feed everything at 6V using a resistor. The load will change, thus changing the voltage.

Pick on voltage and stay with it on everything.

Jim, I have had a one wire alternator on my C for many years and the battery does not go dead, even over the winter.

???????

SDE

Some do some don't. The interesting thing is that the suppliers of the converted Alternators are not all using the same modifications. I believe you are having success. I know of others that have not had luck at all. Thus when I recommend a solution, I want it to be the least likely to disappoint.
No issue with success. Jim

Well Phil: there is a way I was just talking to an auto shop that does electronics and other items.

Their words" contact a shop / outlet that does hot rodding >> converting from new chaise to old body IE; 1980 frame with a 1947 body creating a roadster. the dash will be all 6 volt even the heater fan and lights the rest will be 12 volt alternator battery starter might even be 6 volt depending on the engine. THUS 12 to 6 volt. needs to at least 30 amp capacity plus.
There is a conversion adapter that the roadster rod shops can create or find to do the above.
>>>>Cost that might be an other issue <<<< but it is probably do able.
By the way I still haven't found my schematic but will ask some of out electronic techs at the post office.
best of the day to you.
Wm.

I agree on the "1 wire" alternator of the Delco 10SI type, NOT causing any battery drain.
There once was a type that had the "1 wire" regulator connected to the BAT stud inside the alternator, that would cause a small parasitic drain on the battery, but I have not run into one of those for nearly 30 years. Most of what you see today in a Delco 10SI " one wire" alternator are electrically identical to the standard "3 wire " alternator. The modern "1 wire" unit has nothing changed except the internal regulator. No battery voltage is avlalible to the "1 wire" regulator, as it is only connected to the field circuit, (the diode trio, regulator and rotor.) Battery voltage to the internal parts is effectivly blocked by the 6 diode rectifier assy, exactly as it is in a stock "3 wire" alternator.

It is very easy to test your "1 wire " alternator to make sure it does not have a design that will slowly drain the battery.
With the tractor not running, but with the battery connedcted, remove the big tractor harness ammeter wire that attaches to the BAT stud on the alternator rear. Connect your digital VOM to the bat stud and the harness bat wire, with the meter set on Milli amps, so you can read any parasitic drain from battery to alternator.
I would bet that in 99.9% of "1 wire" Delco alternators, the reading will be exactly the same as any stock "3 wire" alternator, 3 Milli amps or less, with all of that from slight leakage of the rectifier diodes.

The Super M I bought last year has a fairly new 1-wire alternator.

It also has a battery cutoff switch wired into the ground on the battery, and mounted up on the light bar.

The previous owner wired the cutoff in because he was having problems with the battery draining.