Spark plug tech question?

[JustJason]

Re: Spark plug tech question?

I understand that the block is just a path in the circuit. Just a hunk of metal conductor... it doesn't matter if it a pig iron big block, or an aluminum kicker, if there are good connections then voltage drop will be minimal across the block.

What I was getting at was were voltage begins and ends, and where current begins and ends.

As far as I know, and am I by no means an electrical engineer or electrician. (although yes I do have a diploma in marine technology, and eletrical sytems were part of that diploma). That voltage starts and ends at the battery. It doesn't really matter if you feel it starts at the + or - terminal. It matters more that there is a complete loop. In a battery, voltage is the potential difference between the positive and negative terminals... and thats it. Was ben franklin truely wrong... or was he correct? Are electrons negatively charged? Or are they positively charged? True we have many electrical "laws", ohms, watts, etc. But when it comes down to it we have Electron theory and Conventional theory. We do not have Electron or Convential Law.

So that takes care of voltage. Current on the other hand comes from the positive terminal of a battery, where there is a surplus of electrons, and stops at the load in the circuit. At the load current is converted into work/power plus heat because of every loads resistance. If there was no resistance then obviously it would be a short.

That being said. The potential difference remains the same (not accounting for the load drop) across the circuit.

If current traveled throught he block backwards, then everything would have to be diode isolated, which it is not. The only reason putting an amp clamp on either + or - shows the same is because the amp clamp is measuring the magnetic field the wire itself is making, under load, and converting that field strength into a number in amps. It's not actually measuring amps directly.

Buy into whatever theory you choose. If you design circuit boards all day long i'm sure you buy into 1 theory more than another. All I know is what works in boats dudes.

 

[aborgman]

Re: Spark plug tech question?

So in a negative ground system. Where as the block is often a common grounding point, after whatever load in whatever circuit. Your saying current is flowing through the block (even being after the load)???

Absolutely. It has to.

The only way for current to flow is for there to be a completed circuit. In a completed circuit, current will flow through all components of the circuit.

In a standard car motor situation at startup for example:

Key turn trips the solenoid, which shorts the positive cable to the starter motor. Electrons in that situation flow

Battery neg. terminal -> battery neg. cable -> car body/engine block/etc. -> starter motor windings -> batter pos. cable -> Battery pos. terminal.

--
aborgman

 

[aborgman]

Re: Spark plug tech question?

I understand that the block is just a path in the circuit. Just a hunk of metal conductor... it doesn't matter if it a pig iron big block, or an aluminum kicker, if there are good connections then voltage drop will be minimal across the block.

Correct.

What I was getting at was were voltage begins and ends, and where current begins and ends.

Voltage and current don't "begin" and "end".

Voltage is merely the measure of electrical potential difference. It can be measured anywhere, requires no load, etc.

Current is the rate of flow of electric charge.

As far as I know, and am I by no means an electrical engineer or electrician. (although yes I do have a diploma in marine technology, and eletrical sytems were part of that diploma). That voltage starts and ends at the battery.

No... A voltage is created (by chemical reaction) between the two battery terminals.

It doesn't really matter if you feel it starts at the + or - terminal.

It does if you care about the physics of the flow of electricity.

Current flows from positive to negative - but that has no basis in physical reality. That is just a convenient definition chosen by people because they liked it. You could re-define it in the opposite way and it would have zero effect on the underlying mathematics or physics.

Electrons - which are a real thing, not a made up human concept like "current" flow from negative to positive. In a system made of normal resistance and wires - the only thing that moves are electrons... and therefore the only physical flow is that of electrons from negative to positive.

... now throw an airgap in there (or an ionized solution) - and for the segment where the airgap/ionized solution/plasma is located - and you'll see movement in BOTH directions.

Run electricity through a salt water solution and electrons will be moving from negative to positive at the same time positive ions in the solution are moving from positive to negative.

If you want to get really confused - start looking at semiconductors and movement by holes/electrons. You'll find that the mobility difference of the two has a strong effect on the switching speed of transistors.

Are electrons negatively charged?

By definition they are negatively charged - which means they are repelled by other negative charge sources (like the negative battery terminal) and attracted to positive sources (like the positive battery terminal).

But when it comes down to it we have Electron theory and Conventional theory.

Not really. What you're referring to as "conventional theory" isn't theory. It's pragmatic systems used for working with electricity.

Current on the other hand comes from the positive terminal of a battery, where there is a surplus of electrons

No - current comes from electricity flowing through a circuit. A battery doesn't put out "current". It sinks/source current through a load.

...and the surplus of electrons on a battery are at the negative terminal, not the positive. They flow the opposite way as "current" by definition.

and stops at the load in the circuit.

No - current is the same at the source of the circuit as it is at the sink.

Consider the following:

Battery positive terminal -> ammeter1 -> load -> ammeter2 -> battery negative terminal.

The current will be identical at ammeter1 and ammeter2. The current doesn't stop. Every bit of current entering a current loop exits it - no matter how much work it does.

At the load current is converted into work/power plus heat because of every loads resistance. If there was no resistance then obviously it would be a short.

Current isn't converted to heat. Energy is.

Assume the following circuit:

Battery positive terminal -> ammeter1 -> load -> ammeter2 -> battery negative terminal.

What is total voltage drop? 12 volts. Doesn't matter whether the load is .1 ohm, or infinite. The voltage drop in total is always 12 volts - up to the point that the battery can't supply enough current and either internally faults or its output voltage drops.

What is the current at ammeter1? Depends on the load resistance. Assume the load is 120 ohms.

V=I*R. I = V/R. I = 12/120 = .1 amps

What is the current at ammeter2? Exactly the same .1 amps.

If current traveled throught he block backwards, then everything would have to be diode isolated, which it is not.

Current doesn't exist outside the human mind. Current isn't a thing. Current is the change in a thing. Current really has no physical underpinning with regards to direction. It's purely a definition.

If humans had decided that negative velocity = forward, and positive velocity = backward - it wouldn't be any more right or wrong than the current definition. It's just an artificial frame of reference.

The only reason putting an amp clamp on either + or - shows the same is because the amp clamp is measuring the magnetic field the wire itself is making, under load, and converting that field strength into a number in amps. It's not actually measuring amps directly.

Even an in line ammeter doesn't measure amps directly. It measure the voltage drops across an extremely high , precision resistance and uses Ohms law to give a measurement for current.

Clamp on ammeters measure the magnetic field flux strength generated by running an electrical field through a wire.

The reason a clamp on ammeter measures the same whether on the positive or negative line is because the current is the same (just the opposite direction) through both lines.

Buy into whatever theory you choose. If you design circuit boards all day long i'm sure you buy into 1 theory more than another. All I know is what works in boats dudes.

I've designed everything from microprocessors (Pentium 4), to ultra-high current/ultra-low voltage precision resistance measurement systems, to home electrical systems.

Current flows from positive to negative - but it's just an artificial human construct. Actual physical electrons flow from negative to positive...

...and really, really, really slowly at that. In a copper wire signals travel at around 77% of the speed of light. Actual electron flow moves at about 2 mph though.

--
aborgman

 

[Tacklewasher]

Re: Spark plug tech question?

 

[bruceb58]

Re: Spark plug tech question?

The only reason putting an amp clamp on either + or - shows the same is because the amp clamp is measuring the magnetic field the wire itself is making, under load, and converting that field strength into a number in amps. It's not actually measuring amps directly.

All I know is what works in boats dudes.

Why do we even bother?

 

[ThumbPkr]

Re: Spark plug tech question?

I agree,I quit posting a long time ago.Ron G

 

[schematic]

Re: Spark plug tech question?

OK I'll bite....
These are the facts.

-The direction of electron flow across a plug can be in either direction pending on the ignition system design.
-It is very easy to prove the direction with a lead pencil.
-The center electrode and ground electrode will wear differently according to the direction of current flow.
-It takes more required voltage to jump the plug gap if the current flow direction is from the ground electrode to the center electrode. Thats why most old ignition designs are positive ground
-A positive ground wiring system as in many European systems has proven to have less electrical failures than negative ground systems. (easy to prove)
-The ignition system is a separate circuit from the equipments cranking charging system and its polarity is not determined by the battery ground designation. It is determined by effeciency in olden day as ignition systems back then were barely adequate to jump the gap, or convenience with newer systems as with newer designs, voltage is in abundance.

 

[Tim Frank]

Re: Spark plug tech question?

OK I'll bite....
These are the facts.

-The direction of electron flow across a plug can be in either direction pending on the ignition system design.
-It is very easy to prove the direction with a lead pencil.
-The center electrode and ground electrode will wear differently according to the direction of current flow.
-It takes more required voltage to jump the plug gap if the current flow direction is from the ground electrode to the center electrode. Thats why most old ignition designs are positive ground
-A positive ground wiring system as in many European systems has proven to have less electrical failures than negative ground systems. (easy to prove)
-The ignition system is a separate circuit from the equipments cranking charging system and its polarity is not determined by the battery ground designation. It is determined by effeciency in olden day as ignition systems back then were barely adequate to jump the gap, or convenience with newer systems as with newer designs, voltage is in abundance.

Your first three self-proclaimed "facts" are essentially correct, your last three are mostly wrong.....and number 6 contradicts 4&5.
And anyone who has spent hours under the hood of a European car with electrics by Lucas or early Bosch have already hurt themselves laughing at #5.

Most people in this post have tried to use the rules for a simple constant flow circuit to explain a high-voltage momentary discharge circuit....that doesn't work.

If you park 2 vehicles beside each other and run one lead of a test light to the positive battery terminal on vehicle 1, and the second to the neg batt terminal of vehicle 1 it obviously lights....run that second lead to the negative terminal of vehicle 2 and it doesn't.
Reasons are obvious.

Now extend a spark plug lead from vehicle number 1 and connect to a plug on vehicle 2.....it will fire quite happily.....even though the vehicles do not have a common ground.

All that is happening is that you have a large built-up electrical potential difference that discharges across the plug gap...both directions...and verrrry quickly. Then it's done until the next time.
The term "potential difference" is more appropriate here than "voltage".
Thinking in terms of Ohms Law, and series or parallel circuits is going to send you down the wrong path.
The "body of the car, and back to the coil" are red herrings
If you put a twelve foot HT lead on the coil output and held it against ....well say... your spouse or significant other, I wouldn't try explaining that he/she wasn't part of the "circuit" so shouldn't have felt a thing.

The discharge (spark) is simply the system returning to as close to zero potential difference as possible and the direction is almost irrelevant. Much more like scuffing your feet on a carpet in a room with dry air and then touching a brass doorknob. No wires, no series circuit, but there is a pretty good "zzzapppp".

The spark plug electrodes do, however, have polarity, which does not directly influence the direction of spark discharge (it is actually related to the coil polarity and can be derived from the right-hand rule as someone suggested) but does affect the wear-properties/longevity of the specific electrode.
Most often, the centre electrode is negatively charged, but in some ignition systems, and especially "waste spark" systems, 1/2 the plugs have negative-charged centre core, the other half are positive-charged centre core.
Protons are attracted to the negatively charged electrode, electrons to the positive. Ford has, in some models, used two different plugs in the same engine.
The fact that protons have significant mass compared to electrons means that the proton collisions at the negative electrode cause more wear than do electrons at the positive electrode and that accounts for the typical wear.

 

[v1_0]

Re: Spark plug tech question?

Allright, I did some detailed research on this topic, and must admit that I was incorrect with some of my assertions.

I had said "I assert that the copper core will have the same resistance going one way or the other, just as a wire would have."

This is not true in the context of a working spark plug - there is another principle at work here. Electrons flow easier from hot to cold. Since the center electrode of the spark plug is hotter than the body, it takes 15% less voltage to flow from center electrode to the 'body'.

Therefore, a spark plug with a negative electrode and a positive 'body' will provide less resistance than a spark plug that has reversed polarity.

I also found out that what we are referring to as "negative grounding" in the car's electrical system is in reference to how the battery and electrical system hooks up. This does apply to how the coil itself hooks into the car's electrical system, but the spark plug is different.

The polarity of the spark plug is determined by how the coil is hooked up to it, not where the car's battery is grounded.

This means that the spark plug can have a negative electrode regardless of how the battery is grounded - it is the coil design that determines this. The key is that voltage (and subsequent current) is relative.

 

[schematic]

Re: Spark plug tech question?

V1_0
You are on track....

Hi Tim
You must not confuse facts with opinions....I have given you the facts.
Now I will explain...

First off, positive ground is superior for a starting, charging and acc. systems. Freightliner did a study with several identical trucks. Half with + grnd. the other half with -grnd. After several hundred thousand miles, the truck were compared for failures. The + grnd units has way fewer switch and connector failures. Think of it this way...which post on the battery corrodes? The positive post and the wires connected to it attract free electrons from the atmosphere. These incomming electrons drag otherimpurities in the air with them. We refer to this as corrosion. If we connect the frame to the positive post, the corrosion will gather on the frame rather than the system wiring. Thus less electrical failures. (yes European units may experience electrical failures due to poor electronic components, but not from the ground choice)

If you park 2 vehicles beside each other and run one lead of a test light to the positive battery terminal on vehicle 1, and the second to the neg batt terminal of vehicle 1 it obviously lights....run that second lead to the negative terminal of vehicle 2 and it doesn't.
Reasons are obvious.

I'm sorry Tim, but neither connection will lite the testlite because you do not have a completed circuit.

Now extend a spark plug lead from vehicle number 1 and connect to a plug on vehicle 2.....it will fire quite happily.....even though the vehicles do not have a common ground.

Ah but they do have a common ground as far as the ignition is concerned. The air around the vehicles and the tires touching the dirt....

If you put a twelve foot HT lead on the coil output and held it against ....well say... your spouse or significant other, I wouldn't try explaining that he/she wasn't part of the "circuit" so shouldn't have felt a thing.

Ah but she is part of the circuit if she gets the shock. The current will pass through her body, along the ground and through the air back to the vehicle...

Ford has, in some models, used two different plugs in the same engine.

As I said, some manufactures have a positive potential at the center electrode. This is done because it is easier and cheaper for their design to do so as in a waste spark system. Since the most "conventional" spark plugs only have Platinum on the center electrode for wear purposes, ford designed a plug with platinum on the ground electrode for the reverse polarity the waste spark system provides.

and number 6 contradicts 4&5.

See V1_0 comments

Sorry to stomp on you Tim, but I've been do this for a living for 35 years...

 

[v1_0]

Re: Spark plug tech question?

These incomming electrons drag otherimpurities in the air with them. We refer to this as corrosion. If we connect the frame to the positive post, the corrosion will gather on the frame rather than the system wiring. Thus less electrical failures.

Wouldn't this now cause the frame to rot out faster? Especially in areas where they use salt on the roads in the winter?

 

[v1_0]

Re: Spark plug tech question?

Allright, I did some detailed research on this topic, and must admit that I was incorrect with some of my assertions.

I had said "I assert that the copper core will have the same resistance going one way or the other, just as a wire would have."

This is not true in the context of a working sparkplug - there is another principle at work here. Electrons flow easier from hot to cold. Since the center electrode of the sparkplug is hotter than the body, it takes 15% less voltage to flow from center electrode to the 'body'.

Therefore, a sparkplug with a negative electrode and a postivively charged 'body' will provide less resistance than a sparkplug that has reversed polarity.

I also found out that what we are referring to as "negative grounding" in the car's electrical system is in reference to how the battery and electrical system hooks up. This does apply to how the coil itself hooks into the car's electrical system, but the spark plug is different.

The polarity of the spark plug is determined by how the coil is hooked up to it, not where the car's battery is grounded.

This means that the spark plug can have a negative electrode regardless of how the battery is grounded - it is the coil design that determines this.

 

[schematic]

Re: Spark plug tech question?

Wouldn't this now cause the frame to rot out faster? Especially in areas where they use salt on the roads in the winter?

You are right V1_0
In equipment that uses +grnd. the frame are painted well. The electrical system still benefits, but your frame disintegrates....

 

[puddle jumper]

Re: Spark plug tech question?

V1_0
You are on track....

Hi Tim
You must not confuse facts with opinions....I have given you the facts.
Now I will explain...

First off, positive ground is superior for a starting, charging and acc. systems. Freightliner did a study with several identical trucks. Half with + grnd. the other half with -grnd. After several hundred thousand miles, the truck were compared for failures. The + grnd units has way fewer switch and connector failures. Think of it this way...which post on the battery corrodes? The positive post and the wires connected to it attract free electrons from the atmosphere. These incomming electrons drag otherimpurities in the air with them. We refer to this as corrosion. If we connect the frame to the positive post, the corrosion will gather on the frame rather than the system wiring. Thus less electrical failures.



The reason this is easier on the components that are being operated because you switching on the ground side( weather its a positive or negative ground).Japanese auto been do it for a long time.

Think of it like a stream that you have a dam( your switch) and a water wheel( your component). If you open the dam and the water flows down to the water wheel with an impact. Now put that same water wheel up stream of the dam and open the dam. The water wheel just starts turning. This same predicable applies to electrical components and gives you longer life to the components.