6volt starters on 12volts

[boler76]

If it doesnt hurt a 6v starter to be used on 12v, why does the nameplate specify 6v? Does the 6volt starter draw 4 times the current on 12v than what it is designed for??

 

[Paul N Texas]

Originally, that is what the electrical system was setup to use, and the charging system to put out. A 6 volt starter will turn faster on 12 volts for one thing. I haven't really thought about the amps, so someone else will have to cover that. If the ignition system is setup right, you should not have to spin the starter very long anyway. I have found that my 8N starts faster since the conversion, and the only real trouble I have is with dirt in the tank. One of these days, I'll fix that too...

 

[Bob]

Current is limited by counter EMF, which increases as the motor (starter) speeds up, limiting current.

 

[kev8n]

I also believe the mfg. specs. but having said that, I do have a tractor with a 6v starter on 12v system.

It will probably draw just about the same current though I have not verified this by measurement. I won't explain at this point but to say motors just work that way. It will however, be operating at twice the wattage of course, because now P = (Im x 12V) is twice the power of (Im x 6V) so I don't feel real good about the setup.

I do think though, that if you don't just nap on the starter switch ou can probably get away with it for a long time. It's just like that ol' penny in the fuse socket- it hardly ever matters.

fwiw

kevin

 

[duey]

I DO run my 6 Volt starter on a longer #4 cable to reduce the hard hit that 12 volt would otherwise have. As they say, Works good, lasts a long time.

duey

 

[Jerry/MT]

as long as you don"t crank them for long periods, it doesn"t seem to har them. I bought my TO-30 and it all ready had a 12v conversion but still had the 6v starter. the motor is series wound so doubling the voltage about doubles the current. That being the case the heat rejected in the windings goes up by the square of the current or a factor of roughly four. So you don"t want to crank for along period of time. And you should have to because you have about doubled the power output and the motor should spin faster and start easier, give the engine has a good ignition system and is in reasonable mechanincal shape.

 

[old]

In theory on 6 volts a starter will draw twice the amps as it does on 12 volts. There is an equation for that but it has been close to 30 years since I have used it so I do not remember it for sure. Sort of like in your house if you have an AC unit that puts out say 10,000btu but is on 120 volts it will draw twice the amps as a unit that is 10,000btu on 220. Now yes in the long run you do not save much if any in cost because you use more volts but less amps again going back to the theory's as I remember

 

[36 Coupe]

It does hurt the starter and the drive.The 12v converters dont say much about broken bendix springs,drive gears split in half,stripped fly wheel teeth or slipping ring gears.In theory a series DC motor will run twice as fast and draw twice the current if the voltage is doubled.A friend has an 8N with a 12 volt mess in it that wont start.The points are burned up and have little gap.I told him to get it into his garage and I will work on it when I have time.I am working on my barn roof, its using a lot of time.Another friend has a 9n with 12 volt troubles.2 burned out coils and a 100 buck starter rebuild so far.I see the points on the 8n have a black plastic cam block .Junk points.

 

[willie in mn]

Old
Volts x Amps = Watts. In your example of an A.C., it takes a certain amount of watts to do the job, somewhere in the neighborhood of 3.5 BTU/watt. You pay for the number of watts used. Higher voltage takes fewer amps to produce the same number of watts. Lower amps can get by on smaller wires all the way around. Of course everything has efficiency losses, so not exactly perfect, but close enough for this discussion.
Willie

 

[willie in mn]

My theory & I'm sticking to it.
Starter under load(cranking the engine) can draw up to 300 amps, so need heavy cables to do it.
Starter "free wheeling", before the bendix engages, can draw as little as 10 amps, can get by with 10 or 12 gauge wire, still running at rated speed.
Many people will disagree with me.
Willie

 

[Tom N MS]

12 Volt system will outlast me..It works so hit the button and let her fly.

 

[Piker]

When I bought my '47 8N it had been converted to 12V, sort of. Still had the original 6V starter. Once I got the ignition resistance/coil sorted out, first thing that happened was bendix slammed into flywheel, broke off & jammed armature up so bad I had to break starter end bell to get it all removed from the tractor. Replaced with an aftermarket 12V starter c/w new bendix (clutch-type, but still dis-engages too soon occasionally). No more trouble.

 

[NOXJohn]

I have two 8Ns that I have converted to 12 volts and retained the 6 volt starters. My 1950 side mount operates perfectly. It starts on the first revolution and makes no noise. My 1949 front mount starts the same but every once in a while it appears the starter starts to spin before the Bendix engages. I can hear the teeth of the Bendix grinding momentarily against the teeth on the flywheel. Not good. It did not start this until about 40 hours run time after conversion. I have a spare starter that I will soon get converted to 12 volts and replace the 6 volt starter on the 1949 8N. I will also inspect the ring gear and Bendix gear. I plan to leave the 1950 side mount as is unless it starts the same thing. I have no idea why one works fine and the other has problems. I don't know if the starter is the problem on the front mount or if it has something to do with the ring gear or Bendix.

 

[boler76]

Great replies, so now I know there is a reason for nameplate to be stamped 6v. thanks

 

[Greybeard PA]

A few years ago, SKINNED KNUCKLES magazine ran an article on this very subject, written by an electrical engineer. A lot of his math was over my head, but the jist of his story was that a six-volt starter cranking with twelve volt input will turn at 65 percent higher rpm. Electrically, this arrangement is easier on the staarter than six volts. His only caution was that this arrangement will be - as most of us already kknow - hard on bendix drves and flywheels. I have had two 8N's, both converted to twelve volts. They sure do start quickly, and those CS-130 GK alternators start charging right away, at cold idle.

I like.

Dave Erb
New Holland, PA

 

[Dean]

Bingo!

The 6V armature will tolerate intermittent, low duty cycle operation on 12V indefinitely. The 6V field coils, however, will be much less tolerant of excessive cranking, which should be (but is not always) avoided in any circumstance.

The real issue is shock loading of the starter drive and ring gear.

Ford tractor starter motors are rather tolerant of the increased shock loading introduced when 6V starters are operated on 12V but other designs are not nearly so trolerant. Broken starter end castings are rather common on Ferguson, International and other makes when the original 6V starters are routinely operated on 12V.

Dean

 

[lha]

As long as my '41 9n,6v+g starts,I'm not going to worry about lights,starters,etc.If it ain't broke,don't fix it!---lha

 

[old]

I understand that. Being an Ex-Navy E.T. I learned all that stuff just any more since I do not use it much the theory's are still between the ears just the ways to figure them out get lost in all the other stuff packed in there LOL. At one time I could count in binary and octal and do the math in either one but now days it would take me hours to bring that back out of the stored memory LOL

 

[Dell (WA)]

boler.......when the original N-Starters were built, there was NO 12V-batterys. Infact, the N-Ford MPC (master parts catalog) lists the battery as 13-plates. NO VOLTS listed. (FYI 12V did NOT appear until 1956)

In intermittent starter duty, 12V does NOT hurt the 6V starter motor. (and it spins faster for quicker eazier starting) The additional AMPS that the starter coils draw turns into HEAT which is what kills the starter coils. In short duty, the coils don't gitta chance to over-heat. ........HTH, Dell, a 12V advocate for the right reason

 

[36 Coupe]

A free running starter will draw 60 amps easy.My Ford manual says 45 io 85 amps ,there are 3 starters listed.your figures are way off.

 

[36 Coupe]

Ford built Transit buses in 1938 that were 12 volt.

 

[Dean]

In addition, nearly all American made passenger cars were released with 12V electrical systems in the 1955 model year.

Dean

 

[TheOldHokie]

(quoted from post at 08:29:01 11/05/10) In addition, nearly all American made passenger cars were released with 12V electrical systems in the 1955 model year.

Dean

I would just like to point out that just because a vehicle has a 12V system doesn't mean it uses a 12V battery. Multiple battery configurations to produce higher operating voltages are common on machinery.

TOH

 

[JMOR]

(quoted from post at 09:19:18 11/05/10)

(quoted from post at 08:29:01 11/05/10) In addition, nearly all American made passenger cars were released with 12V electrical systems in the 1955 model year.

Dean

I would just like to point out that just because a vehicle has a 12V system doesn't mean it uses a 12V battery. Multiple battery configurations to produce higher operating voltages are common on machinery.

TOH

inda interesting JD with 24 volt system, two 12v batteries, runs most everything except starter on 12v and has BOTH Positive & Negative ground all on same tractor. So much for killing that argument for one type gnd versus the other..JD, covers the bases with BOTH! :twisted:

 

[36 Coupe]

Ford waited until the 56 model .My 61 Rambler had a generator.Altenators cost less to build and are smaller.You cant ram a lot of energy into a battery.When an alternator regulator fails it will destroy the battery.Fast chargers are bad, temperature should be monitored never is.