Coils and Ballast Resistors (Declassified)

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From: Terry Thompson Subject: Re: Coils and Ballast Resistors Date: Wed, 21 Jan 2004 19:40:04 -0800

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That article by masters confuses a lot of people (me
included at one time). It is absolutely correct, but
the terminology and way it is written is confusing if
you're not following the train of thought. So lets
break it down:

WHAT IS A COIL?
A coil is basically a storage unit for energy.
Electrons build-up in the windings via power supplied
by the secondaries. When the circuit is completed by
breaker points OR by the electronic ignition, the
primary winding charge is released in a momentary
discharge that has built-up over those micro-seconds.
This is how you get 40k volts from a 12v source.
When the points or electronic ignition opens the
circuit, the process repeats.

NOT ALL COILS ARE MADE THE SAME
There are two major types of coils: Ballast coils and
non-ballast coils. Here's the tricky part. You might
think a ballast coil means it HAS a ballast..that
would be incorrect. Simply put:
A ballast coil REQUIRES a ballast resistor.
A non-ballast coil is designed to NOT use a ballast
resistor.

You following me so far? If not. Re-read the above
until it makes perfect sense.

WHAT IS THE DIFFERENCE?
A non-ballast coil has an internal resistance built
into it's windings, so that as voltage increases,
voltage capacity drops off. (This is a lucas sport
coil which Dan is describing requires the bypass).

Conversely A ballast coil (remember, this is the coil
which requires a ballast resistor), does not have this
internal resistance built into its windings. Whatever
you pump into this thing will be multiplied like a
transformer. So, if the coil is designed to receive 6v
via a voltage drop from a ballast resistor, and you
start pumping 12v into it, at high RPMS, instead of
getting 40k volts, you will get 80k+ volts.

Now, I don't know which Mallory coil you have. I know
there is a chrome coil for electronic ignitions and
another one for points ignitions. I happen to have the
Mallory breaker points ignition type (model 29217) on
my car and it is a ballast coil. And states very
clearly in the instructions DO NOT REMOVE THE BALLAST
RESISTOR. IF THE VEHICLE DOES NOT HAVE A BALLAST
RESISTOR, INSTALL MALLORY PART #700 (a ballast
resistor)

SUMMARY
If you decide to by-pass the ballast resistor on a
ballast coil regardless of directions, YOU WILL:
1) Increase the voltage to as much as 80k volts at
high rpms!
2) Possibly destroy your coil
3) Burn out your condensor every time your tac hits
~4000 rpm
4) lasty but not leastly, go through breaker points
like a fat man through a box of jelly donuts.

Conversely, if you run a ballast resistor after
installing a non-ballast coil, very little will change
at low rpms. But at your higher rpms, the voltage will
decrease dramatically and you will most likely have a
very weak spark.

-Terry

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Since we are free to express our opinions here, *I* thought the article was a misleading crock of rhubarb fertilizer!!! That's nothing at all like we were taught at Spartan School of Aeronautics in the late 60's and early 70's. I don't know HOW those aircraft engines work with todays modern coils "... storing electrons..." and "...spark occuring when the points close".

This must be a test to see if electrical stuff really does operate on smoke, 'cause when you let it out, it quits!!!!

But pay no mind to my opinion.... long as you're happy with your own. duey

But wrong.
The high voltage spark occurs when the points OPEN.
You could say that the coil stores up the moving electrons and when the points OPEN they all bunch up together and jump across your sparkies to get home.

Roger in Michigan

The ignition coil is an "Electro-Magnetic-Field" device. When the points close, the surge of DC thru the primary winding developes a HUGE magnetic field that envelopes and surrounds the secondary winding. When the points open, the extreamly FAST COLLAPSE of the magnetic field induces a HIGH VOLTAGE spike in the secondary to sparkle yer sparkies.

About the only thing this "self-appointed expert" author got even semi-correct is there are some ignition coils designed for use with ballast resistors and some ignition coils designed for use without ballast resistors. And eather can be used with and without external resistance with varying degrees of success.

ALL COILS have inherent internal resistance, depending upon the type and size and length of wire used for the windings.

Ballast resistors are resistors made with specialized conductors that automatically change resistance with heat/time. Thats what makes them ballast resistors.

The N-Tractor's squarecan frontmount ignition coil's "infamous ballast resistor" has lowered resistance when COLD for HOTTER SPARKIES for eazier starting. As it heats up, it increases resistance until it stabilizes at about 1.4 ohms in about 2 minutes, even if outside temperature is below ZERO. This characteristic also compensates for reduced battery voltage due to lower chemical action at low temperatures.

BTW, florescent lights have AC ballasts for eazier starting and longer life.

HTH..... .....perfesser Dell, EE