# YZ426 / Busa / GSXR / R6 coil question

Wow we are definitely going down the electrical rabbit hole here Gray. You are making me dig back into info I have not looked up in years. To further present my case, the 'storage' term is acceptable and standardized. Please see the Federal-Mogul guide "All About Ignition Systems", page six, "Ignition Technology Terminology", "Energy Storage", for standardized instructional use of the term. http://beru.federalmogul.com/sites/default/files/ti_07_ignition_coils_gb_2013_lowres_0.pdf

Mathematically speaking- in physics you have the law of the conservation of energy (Joules). The stored energy in an ignition coil can indeed be measured in milli Joules and is a testable process, the result is referred to properly as 'stored energy' or the value E in expressed equations. If you go back to the old school days of designing ignition systems for race cars, being able to calculate this was critical in selecting the most optimal coils for a particular application.  This is still an extremely valuable electrical property and in use by all designers / manufacturers of ignition coils.

Here is a very good layout of a DIY test setup for determining coil energy storage values: http://dtec.net.au/Ignition%20Coil%20Energy%20Testing.htm

You can correctly and acceptably state that ignition coils store and discharge energy, even though they are based on the transfomer principal. With a typical inductive ignition coil,  12v is applied and as the primary coil current ramps up, energy is being stored. The energy stored is measurable by calculating:

E = (1/2) * L * I^2, where L is the inductance of the primary coil, and I is the current.

This math is exactly like formulas for energy on a charged capacitor, such as:

E = (1/2) * Capacitance * Voltage^2 - or - Kinetic energy of a moving mass: E = (1/2) * Mass * velocity^2

This is my basis for use of the specific term 'storage', albeit overly and purposefully informal in my initial post- but I never meant it in the sense of similar to a battery. More as my own casual way to express difference with a CDI coil from a Kettering coil, even though at the engineering level they are both operating on the exact same physics and principals.

- E.G. In my own low-level layman non-engineering terms, a CDI coil is only responsible for transferring and magnifying the energy to spark whereas a Kettering coil is responsible for building / storing the charge as well as transferring / magnifying it to spark.    Is that statement wrong from a purely electrical engineering standpoint ? Sure is, no argument there.  Is it ok to use in most non-engineering places casually as a way to simply decribe a difference in coil operation without getting into an engineering detailed discussion? it's been acceptable at least until now.. lol

I was going to say as well Gray- Your last post was nicely constructed and I enjoyed reading it, particularly your point on how one can incorrectly infer operation based on perceived time of events- Very true. My only continued exception is with dismissal of the term storage as it is correct and a recognized measurable property. On that we can always agree to disagree

... a CDI coil is only responsible for transferring and magnifying the energy to spark whereas a Kettering coil is responsible for building / storing the charge as well as transferring / magnifying it to spark.    Is that statement wrong from a purely electrical engineering standpoint ? Sure is...

Q: what is the input voltage applied to the primary on the Kettering coil?

A: ~12v

Q: what is the output of the Kettering secondary?

A: ~25,000v

Q: What is the electrical process by which this increase is achieved?

A: Inductance

Q: what is the input voltage applied to the primary on the CDI?

A: ~250v

Q: what is the output of the CDI secondary?

A: ~40,000v

Q: What is the electrical process by which this increase is achieved?

A: Inductance

Q: What's the difference?

A: None

"Storage" is still the wrong term, however often it's used or by whom, and can only avoid being misinterpreted if it's used in a sufficiently well detailed context.  When a capacitor or a battery is supplied with electrical energy, then disconnected and the circuit left open, that is "storage", analogous to pouring water into a cup.  It's a static and persistent condition, meaning that the charge will stay there over time absent any sort of outside maintenance.  You can measure what's stored, add to it, or get it back out whenever you're ready to.

Conversely, when you say that a magnetic field stores energy, that is a transient, dynamic condition, dependent on an outside force for maintenance, analogous to the energy "stored" in a compressed spring.  Yes, the energy is there, but as soon as the force that put it there is removed the energy is released and gone.  Thus, the energy "stored" in a magnetic field depends for its existence on the current flowing in the conductor.  Once the current is shut off, it last no longer than it takes to flow out into the circuit and vanish. There's a big difference.

Additionally, apart from disagreeing on the use of that term in describing the function of an inductive device, the other main problem I have with your analysis of the two systems is the suggestion that the coils in the two types of systems operate on different principals, or have a different task to perform.  They don't.  They are different because of the differences in the systems they operate within, but both do exactly the same thing in exactly the same way, the only difference being the input voltage and the stepping ratio.

Why does that matter if we aren't engineers? Because we're technicians, and we have to have an accurate technical understanding of what we work on, or we may make incorrect diagnoses of the problems we encounter.  Speaking from over 45 years of professional experience, the single biggest reason the average Joe can't find a competent mechanic to fix his car is because too many of them don't have a deep enough technical understanding of how the equipment they work on is supposed to function when it's working right to be able to accurately determine why it doesn't work.

With that, I will leave this one where it is.

Well I don't know what else to say Gray, I've given verified evidence of energy storage, ignition manufactuer training materials covering terminology, the testing process to measure storage, and the mathematical formula as the foundation. These are accepted, correct terms and methods. What I'm reading is you're essentially saying the entire rest of the physics and electrical engineering world is wrong, and you're right. That's cool man, you got a big sack and I can respect that. Plus you are the moderator here and well, the mod is always right.

Can we get back OT? I'm sure you and I could go at this till the cows come home- nothing like a technician and an engineer getting into a contentious debate on how something works, eh?

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