Home |Gallery |Forum |Ads Today's Tractors
Today's TractorsThe Modern Tractor Resource Page

 
Featured Photo

Click to View

The Market
Tractor Parts
Tractor Manuals
Classified Ads
Tractor Shop

Features
Discussion Forum
Archives
Tractor Photos
Implement Photos
Combine Photos
Information
Model Profiles
Safety Issues
Manufacturers
Reading Room

Miscellaneous
Contact Us
Antique Tractors
Classic Trucks
Kountry Life
YT Forums
Discount Parts

[Home]
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   Traditional YT Forum ViewClassic View   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

This is the modern view of the Today's Tractors Forum. Just login with your YT Userid and password to post. If you have trouble logging in, contact us by email to support at ytmag.com, or through the Reader Form, and we will get you going right away.

Click here to return to Yesterday's Tractors Forum Index

6 volt system, has a 12 volt coil


 
Post new topic    Today's Tractors Forum Index -> Farmall & International Harvester (IHC)
View previous topic :: View next topic  
Author Message
MikeK
Guest






Report to Moderator

PostPosted: Fri Nov 23, 2007 8:15 pm    Post subject: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Hello,

My 1948 farmall H will not start, so I dug into the ignition system. The condenser was bad, but before I put back together, I noticed that the Coil is a 12volt. The system is a 6 volt, the tractor ran but I only started it 10 times after I bought it, before I started to restore it.

Will this 12 volt coil be ok, or is this the reason my condenser is fried?

Thanks for your help
 
Back to top
old
Tractor Guru


Joined: 12 Mar 2000
Posts: 56759
Location: Lake of the Ozarks area of MO

Report to Moderator

PostPosted: Fri Nov 23, 2007 9:18 pm    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Well it could be that it has a 12 volt coil which needs a ballast resister and if so then would you believe the coil is really a 6 volt coil. Most coils will say right on the external resister need or something about no resister need
Hobby farm

 
Back to top
View user's profile
Hugh MacKay
Tractor Guru


Joined: 24 Oct 2001
Posts: 15361


Report to Moderator

PostPosted: Sat Nov 24, 2007 2:30 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Mike: Most situations we encounter on here are folks switching to 12 volt and putting a resistor in the system to reduce the voltage going to a 6 volt coil. Think about this, you already have reduced voltage going to a 12 volt coil. If you add a resistor you'll only reduce the voltage further. My thoughts if you have a true 12 volt coil your voltage at the points is already too low, the resistor will only reduce voltage even further. Your solution is go to a 6 volt coil.

Another factor you must consider is for some weird reason some 12 volt coils are labled 12 volt coil no external resistor required, while others are labled 12 volt coil requiring a added resistor. As I see it the first one is a true 12 volt coil, while the second example is nothing more than a 6 volt coil requiring a resistor when used as 12 volt. Why industry doesn't just call them 12 and 6 volt coils, beats me.
 
Back to top
View user's profile
Nebraska Cowman
Tractor Guru


Joined: 10 Aug 2003
Posts: 11217
Location: Wellfleet NE

Report to Moderator

PostPosted: Sat Nov 24, 2007 4:16 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

What the truth is is that ALL coils are 6 volt. They either have an internal resistor or they don't. The ones with the internal resistor will generally be marked 12v.
 
Back to top
View user's profile Visit poster's website
Hugh MacKay
Tractor Guru


Joined: 24 Oct 2001
Posts: 15361


Report to Moderator

PostPosted: Sat Nov 24, 2007 4:36 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Howard: I know that, but you have to admit the labeling does create confusion for the average guy. I have suposedly two 12 volt coils. The one on my 130 is labeled 12 volt coil no external resistor required. The 12 volt coil on my 140 is labeled 12 volt coil, no mention of a resistor external or internal. I assume the same product, however are they?
 
Back to top
View user's profile
Janicholson
Tractor Guru


Joined: 30 Jan 2004
Posts: 21151
Location: St. Cloud, MN

Report to Moderator

PostPosted: Sat Nov 24, 2007 6:08 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Hugh, I can answer that.
Engineers found out by testing and consumer input, that if a 12v system coil was designed to have neither an internal or external resistor, the reduction in starting voltage from the starter draw would reduce the coil output enough to compromise the starting capability. So automakers, and eventually tractor manufacturers. installed systems to compensate. They ran two wires to the ignition, one from the starter relay/solenoid directly to the coil, and one through the ignition switch to a resistor (Ford used a pink wire in the loom that was a resistor, while others used a block ceramic resistor)

The resistor bypass wire (that was connected to a terminal often labeled "I" on the solenoid or relay) allowed the 10 volts, of the remaining battery volts, to power the coil above the normal run voltage of the coil 10 volts on what is essentially a 6v coil. this raised the output at a time it was most needed, starting.

Another method of doing this is to use a thermal resistor that starts out cold and has low resistance, then gets hot and resists down to the 6v range. These can be internal (most) or external, allowing a simplified wiring system and about the same results. Seasons greetings from central MN Jim
 
Back to top
View user's profile
John T
Tractor Guru


Joined: 14 Dec 1998
Posts: 14079


Report to Moderator

PostPosted: Sat Nov 24, 2007 6:11 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Mike, a 12 volt coil will produce a spark if only supplied with 6 volts but it will be weak and no, I dont see that as the cause of your condensor problems. Ive seen coils labeled:

"12 Volts NOT for use with external ballast resistor" which are indeed full true 12 volt coils

"12 volts for use with (or requires) external ballast resistor" They are indeed actually 6 volt coils and such will work fine on a 6 volt tractor. They are used on 12 volt tractors that use a 6 volt coil and most have the start by pass feature which allows for a hotter start up spark, They sort of start on 12 volts and run on 6 volts.

Theres a common misperception (old wives tale) out there that all coils are 6 volt coils simply NOT true. A full true 12 volt coil has a primary winding resistance (measured between its lil + and - terminals) of around 2.5 to 3.5 ohms or so while a 6 volt coils is more like 1.25 to 2 ohms. ALSO some people refer to 12 volt coils as "internally ballasted" which some think have a built in discrete ballast resistor wired in series before the coil winding HOWEVER most achieve the added primary winding resistance simply either by having more primary wire/winding length or else use wire having a higher resistance per unit of measurement.

One limiting factor and the reason 6 and 12 volt coils are indeed different concerns the life of the ignition contact points which is limiting the current they are required to switch unde load to around 3 to 4 amps or so..... Thats why a 6 volt coil has say 1.5 ohms or primary resistance 6/1.5 = 4 amps) and a 12 volt coil say 3 ohms (12/3 = 4 amps)...... AND THEY ARE NOT ALL THE SAME 6 VOLT COIL........

BOTTOM LINE you need a 6 volt coil on a 6 volt tractor cuz a 12 volt coil will produce a weak spark. All coils are NOT 6 volt coils, see the explanation and reasons why above

Yall take care now

John T
 
Back to top
View user's profile
John T
Tractor Guru


Joined: 14 Dec 1998
Posts: 14079


Report to Moderator

PostPosted: Sat Nov 24, 2007 6:16 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

They probably are HOWEVER the way to tell for sure if its a 12 or a 6 volt coil is to measure the primary winding resistance between the lil + and - terminals. A 6 volt coil is around 1.25 to 2 ohms while a 12 volt is more like 2.5 to 3.5 or so. My post above explains the reasons why, which is to limit the amount of current the points have to switch to around 3 to 4 amps.

John T
 
Back to top
View user's profile
John T
Tractor Guru


Joined: 14 Dec 1998
Posts: 14079


Report to Moderator

PostPosted: Sat Nov 24, 2007 6:26 am    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Excellent, as an aside, on some makes of tractors that used a saddle starter mount mechanical push to start switch instead of an electric solenoid, the ballast by pass feature was achieved by an extra lil small terminal on the side of the starter switch which was hot ONLY while the switch was engaged. A lil wire was ran from there up to either the coils input or ballast output terminal (same ponnt electrically)......... Sooooo many of those got disabled over the years either cuz the wire got left off or disconencted or else the switch was replaced with one a lil cheaper that lacked that extra lil side terminal.....

As you well explained, that feature could really improve cold weather starting cuz when its cold the battery is less efficient PLUS the engine is harder to crank and the high starter current draw drops battery voltage drastically causing a weak spark WHEN YOU NEED IT THE MOST

Yall take care now

John T
 
Back to top
View user's profile
Michael Koch
Guest






Report to Moderator

PostPosted: Sat Nov 24, 2007 8:36 pm    Post subject: Re: 6 volt system, has a 12 volt coil Reply to specific post Reply with quote

Hello,

Thanks for all the help! I checked the coil and it is running avout 1.7-1.9 ohms. So it must be a 6 volt coil, with 12v on the side.

Again thanks for the help. I hope to try this out this week.
 
Back to top
Display posts from previous:   
Post new topic    Today's Tractors Forum Index -> Farmall & International Harvester (IHC) All times are GMT - 8 Hours
Page 1 of 1

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group
Advertisement
Repair/Service manuals available for Allis, Ford, Farmall, John Deere and most other makes and models of tractors. If you are expecting to make repairs to your tractor, check our large online catalog of manuals. We probably have just what you need! Current Special - FREE book offer.    [Click here to visit this Sponsor]

Home | Manuals | Parts

Reproduction of any part of this website, including design and
content, without written permission is strictly prohibited.
Copyright © 1997-2013 TodaysTractors.com

Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others.