12 volt conversion gone wrong

Dale2

Member
I am working to clean up A 12 volt conversion on a 2n ford. Can someone tell me what voltage should be at the coil when the key is on and the points are closed. If I know that I can get the correct ballast resistor to add in series with the coil to prevent from overheating the coil.
Thanks to all
 
(quoted from post at 16:37:15 12/15/17) I am working to clean up A 12 volt conversion on a 2n ford. Can someone tell me what voltage should be at the coil when the key is on and the points are closed. If I know that I can get the correct ballast resistor to add in series with the coil to prevent from overheating the coil.
Thanks to all

There is only one ballast resistor. the extra resistor use to drop voltage is not a ballast resistor.
 
(quoted from post at 18:49:30 12/15/17) not sure are they marked some way? can you tell me both voltages?
sually no markings. 6v coil on those front mounts usually measure about 1 Ohm (+/- a fraction ) on primary terminals. The 12v coils about 2.5 Ohms (+/- a fraction ). You need a resistance in series such that the resulting current is 4 amperes steady state (points closed, engine stalled).
 
(quoted from post at 19:32:28 12/15/17)
(quoted from post at 16:37:15 12/15/17) I am working to clean up A 12 volt conversion on a 2n ford. Can someone tell me what voltage should be at the coil when the key is on and the points are closed. If I know that I can get the correct ballast resistor to add in series with the coil to prevent from overheating the coil.
Thanks to all

There is only one ballast resistor. the extra resistor use to drop voltage is not a ballast resistor.
Well,......................
BALLAST:
A heavy material carried in a ship to provide draft & [b:094d88defa]stability[/b:094d88defa]. A [b:094d88defa]ballast resistor[/b:094d88defa], specifically, is a resistance inserted in an electrical circuit for the purpose of [b:094d88defa]stabilizing[/b:094d88defa] (maintaining a near steady current) in the presence of varying values in the rest of said circuit, such as applied voltage (battery), or variances in other resistive elements (coil primary resistance in the case under discussion here).
For illustration, let us say that coil primary resistance is 0.5 Ohms, with a fixed series 'ballast' resistor of 1.0 Ohms (for a total resistance of 1.5 Ohms). Then with a 6 volt supply, current would be 6/1.5 = 4 amperes. This would result in 4A X 0.5 Ohms = 2 volts across coil primary. NOW, let us simply use a 2 volt battery supply with that same 0.5 Ohm coil & you see that we still have a coil current of 2v/0.5 Ohms = 4 amperes. Next, we will illustrate the [b:094d88defa]stabilizing benefit of a ballast resistor.[/b:094d88defa] We will see the coil primary resistance increase from 0.5 Ohms by 33% (due to temperature rise induced in the copper wire windings) to 0.665 Ohms. WITH the stabilizing ballast resistor, the 'at temperature' coil current will be 6v/(1.33 X 0.5) +1 = 6/1.665 = 3.6 amperes. So, we see that we have fallen short of our 4 ampere goal of 4 amperes at the 'hot current' of 3.6 amperes or a 10% deficit. HOWEVER, [b:094d88defa]without a stabilizing ballast resistor[/b:094d88defa], the 'hot current' is seen to be 2v/0.665 Ohms =3 amperes, for s deficit of 1 ampere or 25% defecit!

Here the question becomes 25% or 10% deficit?
Clearly, the ballast resistor has a beneficial stabilizing effect on cool current. Perhaps we want even better stability of coil current. How? Use a [u:094d88defa]"temperature dependent" ballast resistor, such as Ford's 12250 ballast resistor,[/u:094d88defa] where it's resistance increases with heat & decreases with cold. Now, as the coil heats in use & coil current drops, the 12250 resistor will cool down due to lower current passing through it and the 12250 resistance will drop, thus tending to off set the current fall resulting from the hot coil winding resistance increase. This is an additional current stabilizing effect, above and [u:094d88defa]beyond a simple fixed value ballast resistor. [/u:094d88defa]
An additional benefit of the temperature dependent 12250, come on a cold winter day when trying to start a cold soaked engine with a cold (reduced capacity) battery. The 12250 resistance will be very low (about 0.3 Ohms or less) which helps maintain a proper coil current even under the severe conditions. Perhaps a battery at only 4.5 volts (instead of 6v) when loaded by the hard working starter trying to rotate parts with honey/thick freezing temperature oil. 4.5/(0.3 + 0.5) Ohms = 5.6 amperes coil current. So, maybe it will still fire off and make a happy camper!

Now my 'rant': [b:094d88defa]Both [/b:094d88defa]fixed resistor & temperature dependent (12250) resistors are in fact [b:094d88defa]current stabilizing ballast resistors. [/b:094d88defa] Clearly the 12250 has additional benefit illustrated above. Many posters have the habit of indicating the a fixed resistor is [u:094d88defa]not[/u:094d88defa] a ballast resistor while a Ford 12250 resistor [u:094d88defa]is[/u:094d88defa] a ballast resistor. To repeat, [b:094d88defa]Both [/b:094d88defa]fixed resistor & temperature dependent (12250) resistors are in fact coil current stabilizing ballast resistors. If one wishes to differentiate between temperature dependent ballast resistors and fixed ballast resistors, then that is good. I prefer to do that by referencing the Ford 12250 part number vs a simple add on fixed resistor.

Good night, Merry Christmas & Happy New Year to all.
 
(quoted from post at 19:21:11 12/15/17)
(quoted from post at 19:32:28 12/15/17)
(quoted from post at 16:37:15 12/15/17) I am working to clean up A 12 volt conversion on a 2n ford. Can someone tell me what voltage should be at the coil when the key is on and the points are closed. If I know that I can get the correct ballast resistor to add in series with the coil to prevent from overheating the coil.
Thanks to all

There is only one ballast resistor. the extra resistor use to drop voltage is not a ballast resistor.
Well,......................
BALLAST:
A heavy material carried in a ship to provide draft & [b:62a69b30df]stability[/b:62a69b30df]. A [b:62a69b30df]ballast resistor[/b:62a69b30df], specifically, is a resistance inserted in an electrical circuit for the purpose of [b:62a69b30df]stabilizing[/b:62a69b30df] (maintaining a near steady current) in the presence of varying values in the rest of said circuit, such as applied voltage (battery), or variances in other resistive elements (coil primary resistance in the case under discussion here).
For illustration, let us say that coil primary resistance is 0.5 Ohms, with a fixed series 'ballast' resistor of 1.0 Ohms (for a total resistance of 1.5 Ohms). Then with a 6 volt supply, current would be 6/1.5 = 4 amperes. This would result in 4A X 0.5 Ohms = 2 volts across coil primary. NOW, let us simply use a 2 volt battery supply with that same 0.5 Ohm coil & you see that we still have a coil current of 2v/0.5 Ohms = 4 amperes. Next, we will illustrate the [b:62a69b30df]stabilizing benefit of a ballast resistor.[/b:62a69b30df] We will see the coil primary resistance increase from 0.5 Ohms by 33% (due to temperature rise induced in the copper wire windings) to 0.665 Ohms. WITH the stabilizing ballast resistor, the 'at temperature' coil current will be 6v/(1.33 X 0.5) +1 = 6/1.665 = 3.6 amperes. So, we see that we have fallen short of our 4 ampere goal of 4 amperes at the 'hot current' of 3.6 amperes or a 10% deficit. HOWEVER, [b:62a69b30df]without a stabilizing ballast resistor[/b:62a69b30df], the 'hot current' is seen to be 2v/0.665 Ohms =3 amperes, for s deficit of 1 ampere or 25% defecit!

Here the question becomes 25% or 10% deficit?
Clearly, the ballast resistor has a beneficial stabilizing effect on cool current. Perhaps we want even better stability of coil current. How? Use a [u:62a69b30df]"temperature dependent" ballast resistor, such as Ford's 12250 ballast resistor,[/u:62a69b30df] where it's resistance increases with heat & decreases with cold. Now, as the coil heats in use & coil current drops, the 12250 resistor will cool down due to lower current passing through it and the 12250 resistance will drop, thus tending to off set the current fall resulting from the hot coil winding resistance increase. This is an additional current stabilizing effect, above and [u:62a69b30df]beyond a simple fixed value ballast resistor. [/u:62a69b30df]
An additional benefit of the temperature dependent 12250, come on a cold winter day when trying to start a cold soaked engine with a cold (reduced capacity) battery. The 12250 resistance will be very low (about 0.3 Ohms or less) which helps maintain a proper coil current even under the severe conditions. Perhaps a battery at only 4.5 volts (instead of 6v) when loaded by the hard working starter trying to rotate parts with honey/thick freezing temperature oil. 4.5/(0.3 + 0.5) Ohms = 5.6 amperes coil current. So, maybe it will still fire off and make a happy camper!

Now my 'rant': [b:62a69b30df]Both [/b:62a69b30df]fixed resistor & temperature dependent (12250) resistors are in fact [b:62a69b30df]current stabilizing ballast resistors. [/b:62a69b30df] Clearly the 12250 has additional benefit illustrated above. Many posters have the habit of indicating the a fixed resistor is [u:62a69b30df]not[/u:62a69b30df] a ballast resistor while a Ford 12250 resistor [u:62a69b30df]is[/u:62a69b30df] a ballast resistor. To repeat, [b:62a69b30df]Both [/b:62a69b30df]fixed resistor & temperature dependent (12250) resistors are in fact coil current stabilizing ballast resistors. If one wishes to differentiate between temperature dependent ballast resistors and fixed ballast resistors, then that is good. I prefer to do that by referencing the Ford 12250 part number vs a simple add on fixed resistor.

Good night, Merry Christmas & Happy New Year to all.

Thanks for the lesson, but still don't know if he is talking about fixed resistor or the original OEM ballast resistor that get hot.
Think I will still use the terms fixed and ballast resistors.
 
Do you have the document 'WIRING PICTOGRAMS by JMOR'? If not, get one. They are available for free download at the other Ford N-Series Tractor club site under HOW-TO's/ELECTRICAL. There's nothing wrong with a 12-volt conversion, but many 12-volt conversions are cobbled together electrical nightmares done hastily by folks who just don't know what they are doing. I think I've seen just about every hackmaster 12-volt 'conversion' out there. There is more to it than just slapping a 12-volt car battery on. Get a download, keep it handy, and see all the correct ways to wire these old N's whether 6-volt or 12-volt.

Tim Daley(MI)
 
Thank you that's all I needed to know, Everyone gets carried with terminoly people use
thanks again
 
(quoted from post at 09:18:49 12/16/17) Thank you that's all I needed to know, Everyone gets carried with terminoly people use
thanks again
ncorrect or loose terminology only leads to confusion and/mis-communications.
 
(quoted from post at 23:45:16 12/15/17)
(quoted from post at 19:21:11 12/15/17)
(quoted from post at 19:32:28 12/15/17)
(quoted from post at 16:37:15 12/15/17) I am working to clean up A 12 volt conversion on a 2n ford. Can someone tell me what voltage should be at the coil when the key is on and the points are closed. If I know that I can get the correct ballast resistor to add in series with the coil to prevent from overheating the coil.
Thanks to all

There is only one ballast resistor. the extra resistor use to drop voltage is not a ballast resistor.
Well,......................
BALLAST:
A heavy material carried in a ship to provide draft & [b:7cf3e1bcfb]stability[/b:7cf3e1bcfb]. A [b:7cf3e1bcfb]ballast resistor[/b:7cf3e1bcfb], specifically, is a resistance inserted in an electrical circuit for the purpose of [b:7cf3e1bcfb]stabilizing[/b:7cf3e1bcfb] (maintaining a near steady current) in the presence of varying values in the rest of said circuit, such as applied voltage (battery), or variances in other resistive elements (coil primary resistance in the case under discussion here).
For illustration, let us say that coil primary resistance is 0.5 Ohms, with a fixed series 'ballast' resistor of 1.0 Ohms (for a total resistance of 1.5 Ohms). Then with a 6 volt supply, current would be 6/1.5 = 4 amperes. This would result in 4A X 0.5 Ohms = 2 volts across coil primary. NOW, let us simply use a 2 volt battery supply with that same 0.5 Ohm coil & you see that we still have a coil current of 2v/0.5 Ohms = 4 amperes. Next, we will illustrate the [b:7cf3e1bcfb]stabilizing benefit of a ballast resistor.[/b:7cf3e1bcfb] We will see the coil primary resistance increase from 0.5 Ohms by 33% (due to temperature rise induced in the copper wire windings) to 0.665 Ohms. WITH the stabilizing ballast resistor, the 'at temperature' coil current will be 6v/(1.33 X 0.5) +1 = 6/1.665 = 3.6 amperes. So, we see that we have fallen short of our 4 ampere goal of 4 amperes at the 'hot current' of 3.6 amperes or a 10% deficit. HOWEVER, [b:7cf3e1bcfb]without a stabilizing ballast resistor[/b:7cf3e1bcfb], the 'hot current' is seen to be 2v/0.665 Ohms =3 amperes, for s deficit of 1 ampere or 25% defecit!

Here the question becomes 25% or 10% deficit?
Clearly, the ballast resistor has a beneficial stabilizing effect on cool current. Perhaps we want even better stability of coil current. How? Use a [u:7cf3e1bcfb]"temperature dependent" ballast resistor, such as Ford's 12250 ballast resistor,[/u:7cf3e1bcfb] where it's resistance increases with heat & decreases with cold. Now, as the coil heats in use & coil current drops, the 12250 resistor will cool down due to lower current passing through it and the 12250 resistance will drop, thus tending to off set the current fall resulting from the hot coil winding resistance increase. This is an additional current stabilizing effect, above and [u:7cf3e1bcfb]beyond a simple fixed value ballast resistor. [/u:7cf3e1bcfb]
An additional benefit of the temperature dependent 12250, come on a cold winter day when trying to start a cold soaked engine with a cold (reduced capacity) battery. The 12250 resistance will be very low (about 0.3 Ohms or less) which helps maintain a proper coil current even under the severe conditions. Perhaps a battery at only 4.5 volts (instead of 6v) when loaded by the hard working starter trying to rotate parts with honey/thick freezing temperature oil. 4.5/(0.3 + 0.5) Ohms = 5.6 amperes coil current. So, maybe it will still fire off and make a happy camper!

Now my 'rant': [b:7cf3e1bcfb]Both [/b:7cf3e1bcfb]fixed resistor & temperature dependent (12250) resistors are in fact [b:7cf3e1bcfb]current stabilizing ballast resistors. [/b:7cf3e1bcfb] Clearly the 12250 has additional benefit illustrated above. Many posters have the habit of indicating the a fixed resistor is [u:7cf3e1bcfb]not[/u:7cf3e1bcfb] a ballast resistor while a Ford 12250 resistor [u:7cf3e1bcfb]is[/u:7cf3e1bcfb] a ballast resistor. To repeat, [b:7cf3e1bcfb]Both [/b:7cf3e1bcfb]fixed resistor & temperature dependent (12250) resistors are in fact coil current stabilizing ballast resistors. If one wishes to differentiate between temperature dependent ballast resistors and fixed ballast resistors, then that is good. I prefer to do that by referencing the Ford 12250 part number vs a simple add on fixed resistor.

Good night, Merry Christmas & Happy New Year to all.

Thanks for the lesson, but still don't know if he is talking about fixed resistor or the original OEM ballast resistor that get hot.
Think I will still use the terms fixed and ballast resistors.
e said ballast resistor. "Loose" terminology, which encompasses both resistor types. Had he said "my 12250 resistor", then you would KNOW.
 

i will forever use the term u used to differentiate them once.

there are OEM resistors, and there are ceramic blobs :)
 
(quoted from post at 09:42:39 12/16/17)
i will forever use the term u used to differentiate them once.

there are OEM resistors, and there are ceramic blobs :)

That works for me too!! :D
 

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