Basic Coil Tech Question ?

Here is a question that needs a definitive answer.
Does a coil "Know " or "Care" what the battery voltage is ??

 

The amount of voltage going in will have an effect on the voltage going out. This can also affect the coil internally, depending on the internal primary resistance and if it has a resistor built inside. Point ignition and electronic ignition coils have different primary and secondary resistances.

Flatman

 

He said it best. Same reason they tell us to run 10ga. wire to an HEI.

 

I have always used twelve volt coils on my six volt stuff. No difference. It only works with the old cylindrical coils, I think. No internal resistors. The external resistor makes it the proper voltage.

I only have twelve and six volt stuff, so I can't say it works for other voltages. I've also never used a six volt coil in a twelve volt application. It just happens to be easier to find the twelve volt coils around here.

 

That's interesting, because my 12V coils stop firing at 9V and the car quits.

 

Good question !
***uming a coil is a properly wound ,and a fairly late design coil the answer is no. It doesnt know or care what the voltage is, however the system does. Mainly the contacts or ignition control (module) to turn coil on and off.

Example :

A 6 volt car with a ignition coil using a internal resistance of 1.5 amps would have ,using ohms law 4 amps of current thru the contacts.
The same car adding a 12 volt battery and a 1.5 ohm coil would have 8 amps going thru the contacts. It would run but have a very short life of the contact points.

The fix would be to add a extra primary resistor of 1.5 ohms. Then the 12 volt car would have a total primary resistance of 3.0 ohms ( 1.5 plus 1.5) and then the contacts would see 4 amps of current again.
Its actually somewhat more complex than this with the coil using magnetic induction, secoundary resistance factors and condensors etc. But for this discussion this will work.

 

What is the affect of using a 6 volt coil on a 12 volt system?. I have always wanted to know that answer.I have yet to see it, so here is your chance.