Do the coils get hot

[BwanaDik]

This happens on any engine with ignition points (you guys know what they are) where you turn the ignition on but don't start the engine. Happens to my '67 BSA and my Datsun 2000 until I changed it to SS ignition. I did this to my Dad's Chevy when I was a kid and you couldn't touch the coil after about 5 minutes it was so hot. Does it happen on engines with solid state ignitions? I've not been brave enough to try it on the Feejer (or various BMW bikes and cars) as it could be an expensive mistake. I'm thinking of the procedures of loading and checking a PCIII. The ignition is on to power the PCIII but the engine is not necessarily running.

On a similar note, will it trash the solid state ignition if you run the engine with one spark plug unplugged and the plug lead not grounded in any way? I've seen the warning in several service manuals and so always put in a spare plug (for example, when doing a throttle body sync off idle) and ground it whenever I run the engine without all the plugs installed/connected. Or when doing a compression check, remove the plugs from the head and plug them all back into the leads and be sure they are grounded?

 

[ionbeam]

:nerdsmiley: Warning: This contains very low FJR content. Reading the following may result in sudden and spontaneous sleep. Take caution not to allow your head to fall forward which may result in head injuries. If you are in a location where snoring might be embarrassing or inappropriate you should not read this.

The reason that coils get hot is because 12 volts is applied to a completed circuit inside the coil, causing current to flow all the time. Counter intuitively, the coil outputs high voltage when current stops flowing! This is called a Kettering Ignition System. The ignition coil is made of a low voltage primary coil winding, an iron core and a secondary high voltage coil winding. The current flow through the coil is turned on and off by either a point set or a power device in an electronic ignition system.

As current flows through the primary side of the low voltage coil it creates a magnetic field which becomes ‘concentrated’ by the iron core of the coil. When current stops flowing through the primary side of the coil the magnetic field created by the primary low voltage winding collapses. The magnetic lines of flux cut across the iron core and induce a step-up voltage in the secondary high voltage coil. The coil is wound so that there is a ratio of wire turns between the primary and secondary windings. For round numbers, a ratio of 1:400 means that for every one turn of wire on the low voltage coil, there will be 400 turns of wire on the high voltage secondary. Ten volts on the primary winding would cause 4,000 volts to be generated on the secondary windings.

The energy of the spark is mostly related to the amount of current flowing in the primary low voltage windings. The FJR coils have a resistance of 1.5 to 2 ohms, so with the key on but the engine not running there can be 6 amps (70 watts) flowing through the coil – HOT! The secondary winding is 12,000 to 18,000 ohms. The resistance is so high because the wire is much finer and there is so much more wire length (that ratio thingie).

In the old breaker point ignition systems a small cam was added to the top of the distributor shaft. The points were spring loaded electrical switches. The points remained closed until the tip of the distributor cam forced the points apart. This broke the circuit, causing the primary field to collapse and generated the high voltage spike on the output tower of the coil. This system was fraught with weakness.

An electronic igniting system has the same basic Kettering Ignition System functions of opening the primary circuit to induce a high voltage output. In place of a cam on the distributor shaft that opens the points, an electronic ignition system uses a low voltage (12 volts) on/off signal that is timed and generated by a computer to open and close the circuit. In place of the mechanical point set the electronic ignition system uses a form of a power transistor (FET) to do the switching.

There are different types of electronic system designs, some are more robust than others. The system designers may anticipate that the spark plugs are always plugged in when the ignition system is running so they design one way. The ignition system for most motorcycles actually fires two spark plugs with one coil so the designing engineers use a different ignition system that typically is tolerant of a plug wire being open because there should be at least one spark plug completing the high voltage circuit. When the coil fires the high voltage output there is some ‘ringing’ as magnetic fields and voltages bounce back and forth between the primary and secondary windings. What happens on the output of the coil gets reflected back to the primary side of the coil so the electronic ignition needs to be tough enough to snub the reflected power. If there are no spark plugs connected on the high voltage secondary side of the coil the energy wants to go someplace, and if it goes back into the electronic ignition circuit ugly things happen very fast.

(Punches were pulled, this is not complete and some 'artistic' license taken to make the text more meaningful to the general reading audience)

 

[sonicspeed]

:sleepysmileyanim: :sleepysmileyanim: :sleepysmileyanim:

 

[charismaticmegafauna]

(Punches were pulled, this is not complete and some 'artistic' license taken to make the text more meaningful to the general reading audience)

Oh, but it was still good....

And some 'name dropping' (Kettering) -- you could'a put a "Tesla" or two in there, also.....

Tell us again/more about 'magnetic lines of flux' -- and what really is a 'magnetic field'?

And..., how about 'dual-point' ignitions.... j/k (on all of the above)

Thanks for the 'tech-chat', seriously.

 

[BwanaDik]

:nerdsmiley: Warning: This contains very low FJR content. Reading the following may result in sudden and spontaneous sleep. Take caution not to allow your head to fall forward which may result in head injuries. If you are in a location where snoring might be embarrassing or inappropriate you should not read this.
The reason that coils get hot is because 12 volts is applied to a completed circuit inside the coil, causing current to flow all the time. Counter intuitively, the coil outputs high voltage when current stops flowing! This is called a Kettering Ignition System. The ignition coil is made of a low voltage primary coil winding, an iron core and a secondary high voltage coil winding. The current flow through the coil is turned on and off by either a point set or a power device in an electronic ignition system.

As current flows through the primary side of the low voltage coil it creates a magnetic field which becomes ‘concentrated’ by the iron core of the coil. When current stops flowing through the primary side of the coil the magnetic field created by the primary low voltage winding collapses. The magnetic lines of flux cut across the iron core and induce a step-up voltage in the secondary high voltage coil. The coil is wound so that there is a ratio of wire turns between the primary and secondary windings. For round numbers, a ratio of 1:400 means that for every one turn of wire on the low voltage coil, there will be 400 turns of wire on the high voltage secondary. Ten volts on the primary winding would cause 4,000 volts to be generated on the secondary windings.

The energy of the spark is mostly related to the amount of current flowing in the primary low voltage windings. The FJR coils have a resistance of 1.5 to 2 ohms, so with the key on but the engine not running there can be 6 amps (70 watts) flowing through the coil – HOT! The secondary winding is 12,000 to 18,000 ohms. The resistance is so high because the wire is much finer and there is so much more wire length (that ratio thingie).

In the old breaker point ignition systems a small cam was added to the top of the distributor shaft. The points were spring loaded electrical switches. The points remained closed until the tip of the distributor cam forced the points apart. This broke the circuit, causing the primary field to collapse and generated the high voltage spike on the output tower of the coil. This system was fraught with weakness.

An electronic igniting system has the same basic Kettering Ignition System functions of opening the primary circuit to induce a high voltage output. In place of a cam on the distributor shaft that opens the points, an electronic ignition system uses a low voltage (12 volts) on/off signal that is timed and generated by a computer to open and close the circuit. In place of the mechanical point set the electronic ignition system uses a form of a power transistor (FET) to do the switching.

Obviously your Regular Day Job is that of A Consultant

Too bad you don't know the answer either

 

[ionbeam]

Too bad you don't know the answer either

The only part of your questions that I didn't directly answer was the one about compression checking and grounding the plugs. You don't need to put plugs in the caps and ground the plugs, leave the caps open.

What part(s) of your questions do you think I missed?

 

[rushes]

Too bad you don't know the answer either

The only part of your questions that I didn't directly answer was the one about compression checking and grounding the plugs. You don't need to put plugs in the caps and ground the plugs, leave the caps open.

What part(s) of your questions do you think I missed?

I'm just guessing but I think it's kinda like he asked the time and you told him how a clock works? :blink:

I think he was just wondering if the coils get hot, Ignition on, engine not running on a FJR.

Maybe.... :dntknw:

 

[Constant Mesh]

You can easily switch off the power to the ignition coils by engaging the "Engine Stop Switch" on the right handlebar. This switch powers the coils from the ignition switched DC bus. The ECU switches/controls the return side of the coils.

Don't know how an open-circuited spark plug circuit would affect the ECU switching circuits? But it's very likely the ECU has extensive voltage suppression protection and will not be adversely affected by anything happening at the coils.

 

[ionbeam]

The difference between workmanship and craftsmanship is that workmanship is good enough, craftsmanship is better than it has to be. Not every job (answer) needs craftsmanship. I should have given BwanaDik a workmanship answer.

Workmanship answer:

Yes.

No.

No.

Less filling, tastes great!

 

[BwanaDik]

I'm just guessing but I think it's kinda like he asked the time and you told him how a clock works? :blink:

I think he was just wondering if the coils get hot, Ignition on, engine not running on a FJR.

Maybe.... :dntknw:

Bingo! You are correct Sir!

 

[rushes]

Bingo! You are correct Sir!

Glad I could help! :thumbsup:

 

[BwanaDik]

Ok, this general question should have been in specific reference to Power Commander III installation and set up. After reading a whole lot of the Forum info about PCIII's (did the "search" thing), I think the procedure is to have the PCIII installed correctly, me sitting next to the bike with my laptop on my knees, wireless connection going so I can access Wally's smoothness map, and downloading the new program into the PCIII. According to the Powercommander FAQ:

"The message "Power Commander not found" comes up on my interface. What does that mean?

The software is not communicating with the Power commander,. Make sure that the ignition switch is on, the kill switch is in position, and the USB cable is firmly connected to both the Power commander and the computer. Make sure that the unit is staying powered up (gree light will be lit on the face of the unit) and the your cable is connected. The USB cable needs to "snap" into place. Applying ample pressure is sometimes required."

I guess a good question here is "Which position?" Maybe Constant Mesh has the answer, if I put the kill switch into the "off" position, this will turn off the power to the coils but will the PCIII still be powered up?

The FAQ infers that the ignition is on and the kill switch is in the "run" position. So while I'm messing about with the PCIII programing, the ignition is on and there's power going to the coils.

So my question is: Will the coils overheat or damage themselves with the ignition on while I'm taking the time to make adjustments/downloads to the PCIII? Or is part of the procedure to do as CM suggests and put the kill switch in the "off" position with the ignition on? Will there still be power to PCIII?

With the advances in ignitions and electrics in general, I could see the designers upgrading the coils of modern motorcycles to not cook themselves like the ones did in the Points era.

 

[ionbeam]

no

 

[BwanaDik]

Outstanding! Thanks.

Of course that begs the question: Why don't they get hot, given that the in both cases generating a field around the center core then colapsing that field is what makes the spark? For the points system, there is a constant current going thru the points, around the coil, and back to the battery. Much like an induction heater. On the solid state system, the breaking of the current to the coil happens with an FET (?) on the low voltage side. There is some fixed amount of time required for the coil to generate the field after it's energised (points close), forget what's it's called, but that time was well within the time of the points being closed in the old systems. How does it work with the solid state stuff, now knowing that the coils don't get hot? Low current draw compared with the old systems?

 

[rushes]

Outstanding! Thanks.
Of course that begs the question: Why don't they get hot, given that the in both cases generating a field around the center core then colapsing that field is what makes the spark? For the points system, there is a constant current going thru the points, around the coil, and back to the battery. Much like an induction heater. On the solid state system, the breaking of the current to the coil happens with an FET (?) on the low voltage side. There is some fixed amount of time required for the coil to generate the field after it's energised (points close), forget what's it's called, but that time was well within the time of the points being closed in the old systems. How does it work with the solid state stuff, now knowing that the coils don't get hot? Low current draw compared with the old systems?

Now yur wantin' him to 'splain thangs?

He's gonna think yur messin' with him....

 

[DonRed7]

What an awesome place,... :yahoo:

Reading this topic start/to here released a weeks worth of work stress.

Thanks Dik

Cheers

-Don

 

[BwanaDik]

"Bwana" to my friends

"Mr. Dik" to everybody else

(Glad it's not Friday)

 

[gr8eyes]

I'm not sure but I think Ion answered your second set of questions in his first explanation.

 

[ionbeam]

I mistook Mr. ****'s Dik's 220 words over the course of 2 paragraphs of questions as real interest in the subject because it covered several ignition systems, with history, stated he had done some background reading, and listed actual testing situations. I missed the fact that all he wanted was a Y or a N without superfluous details.

I offered up information so that Dik could draw his own conclusions or see areas to research further. In the future when I choose to reply to questions I will always remember this thread. I understand the difference between how the clock works and simply stating the time. If someone wants a simple answer, ask a simple question or face the clock works.