Ignition coil nightmare

[V Mad]

So what is being proposed is that ..
you start with 12volts. You put in a resistor to drop it to 6 volts then you put in a bypass to return it to 12volts because 6 volts isnt quite enough for some conditions and thats considered a boost...... Well if you like think of it as wages. I take some of yours away.... then give it you back later and call it a bonus..... Happy Christmas!!

OK, I will try a different tack. Let's talk about a current boost instead.

The ballast system uses a 1.5 ohm ballast resistor, and a 1.5 ohm coil. add them together makes 3 ohms. The current then is 12/3=4 amps (ohms law).

The non-ballast system uses a 3 ohm coil. Current is 12/3-4 amps.

So, both systems use the same current when running. But now try starting the car. On a day when brass monkeys have a big problem, Stag owners might be getting only 9 volts when cranking their engine.

So on the non-ballasted system you get 9/3=3 amps through their coil. Thats a drop of 25% in coil current, which equates to 46% less spark energy just when you could do with a boost in current.

FEAR NOT! Along comes a brass monkey and says, I have had a bad day too, but at leat I can fix your bad day. Here, fit this ballast coil and resistor you silly man. So he fits the ballast, and finds that when the cranking his ballast is bypassed so full 9 volts is now connected to his 1.5 ohm coil. Being good at schoolboy maths he knows that 9/1.5=6 amps.

The monkey says now you have boosted your coil current by 50% which is a 125% boost in spark energy. No wonder your stag started first turn. Now, help me go look for me balls.

[HersnotHis]

They struggled to fit in 1 battery let alone 2, also what is the difference between 6 doubling to 12 as 12 doubling to 24 I personally think that spiderman would have made a c**p electrician, but he would have been great at designing the web Thank God R&D were not intellectuals otherwise simpletons like me would not have been able to fix them.

But its a 12V battery in both cases! The statement would be OK if the Stag was fitted with a 6V battery. I agree Spideman ain't no electrician - just my point!

[V Mad]

I,m lost , how does the boost work , does that mean the coil get more than 12v . The boost I thought was changing intermittent between the normal 9 v up to 12v . The ballast only serves to lower power not increase .
Having such a crucial part of the ignition system right down under the car amongst the road water salt .
My starter instructions also mentions the choice of doing away with the ballast as its so much more efficient than a normal starter . Like I said we all have different set ups so it's horses for courses .
I do listen Chris and am learning all the time and realise you are very clever with electrics I just find it hard to understand some logic when the alternatives seem so much easier .
Edd

Edd, in our various efforts to explain how/why the ballast system works to give a boost in ignition energy when it is needed, do you understand it now?

The coils in each system are different. The ballast coil is rated at 6 volt. The unballasted coil is rated at 12 volts.

Once started, both ballasted and unballasted coils are getting the same 'power' because they both get their full voltage on normal running. But the ballasted coil gets double its rated voltage under starting conditions.

So that is the boost we are talking about.

[edd]

Edd, in our various efforts to explain how/why the ballast system works to give a boost in ignition energy when it is needed, do you understand it now?

The coils in each system are different. The ballast coil is rated at 6 volt. The unballasted coil is rated at 12 volts.

Once started, both ballasted and unballasted coils are getting the same 'power' because they both get their full voltage on normal running. But the ballasted coil gets double its rated voltage under starting conditions.

So that is the boost we are talking about.

I'm getting there Chris I would love to see if my starter actually takes as much power away as it's a high torque .At present I have a few electrical gremlins so if I ever get cold start issues I know where to look .
Edd

[HersnotHis]

So that is the boost we are talking about.

OK but it ain't a boost! A normally operating 6V coil which is normally receiving a reduced voltage from a 12V base system by use of a ballast is temporarily restored to the normal operating voltage of the car .. a restoration so no boost!

IMHO a crazy design feature particularly as aforesaid concurrent electronics could have been used to deliver 24 V temporarily to a 12 Volt coil - that would have been a boost!

[DJT]

OK but it ain't a boost! A normally operating 6V coil which is normally receiving a reduced voltage from a 12V base system by use of a ballast is temporarily restored to the normal operating voltage of the car .. a restoration so no boost!

IMHO a crazy design feature particularly as aforesaid concurrent electronics could have been used to deliver 24 V temporarily to a 12 Volt coil - that would have been a boost!

One man's Boost is another man's Snickers.

Whatever, the system has been working fine for over 40 years and usually only fails because someone, through ignorance or because he thought he knew better, messed with it by using a 12v coil or double ballast. Leave it as designed and it works perfectly.

[Staggard]

One man's Boost is another man's Snickers.

Whatever, the system has been working fine for over 40 years and usually only fails because someone, through ignorance or because he thought he knew better, messed with it by using a 12v coil or double ballast. Leave it as designed and it works perfectly.

There were plenty of manufactures around at the time using the same system (not only Stags)and as I recall they worked fine as well, and then came along Spiderman

[edd]

Many Triumph owners opt to replace their standard coil with the Lucas Sport coil, to get a hotter spark. Often, though, they neglect to bypass the ballast resistor, used on some of the later models. Failure to do this will negate the benefit of using the hotter coil, as the Sport coil is designed to be used without a ballast resistor. What is the difference between the two types of coils?

Basically, a non-ballast coil is designed to produce full spark output with 12 volts on the input (+ terminal). A ballast coil is designed to produce the same spark output, but with only 6 to 9 volts on the input.

With a non-ballast coil, the input to the coil is the same, 12 volts, whether the engine is running, or being cranked by the starter motor. With a ballast coil, the starter relay1*by-passes the ballast resister when the starter motor is spinning the engine, and applies the full 12 volts to the coil. Since the coil is designed to provide full spark with reduced voltage, the application of the full 12 volts produces a much hotter spark, which is an aid in starting. After the engine starts, and the starter motor is off, the coil voltage is dropped to the lower voltage, and the coil output is the same as for a non-ballast coil. The reason the ballast type coil is not run at the full 12 volts, for a hotter spark, is to prevent damage to both the coil and the points.
Hope this helps . Sometimes it hard to grasp things and get a full understanding as certain words can be taken or misunderstood .
I found this explanation on the net it's basically the same as what's been said but may help some trying to understand .

[V Mad]

Edd, regarding the why and the hows of the ballasted ginition system I think we are now singing from the same hymn sheet! I do think its important that owners dont discard, out of ignormance or misunderstanding, something that was put there for a good reason.

Regarding what to fit with electronic igniton systems, this also needs some clarification for a few reasons. One is that not all electronic systems are the same. Another is the confusion caused by companies that sell various ignition parts, but dont really understand the technicalities of them. You have to remember that they are basically retailers, not engineers. Also, some retailers like to use superlatives such as high power, high energy etc to make the product sound better when it is difficult to see that this is in fact the case. Another confusion arises because the retailers do not necessarily know each model or marque, so the application data may not be adequate or correct for the Stag.

To answer your question about what is different about the sports coils, or gold coil etc etc, this is where you have to be discriminate and check the specs for coil resistance. I would avoid any coil that boasts a hotter spark, higher voltage, or some similar superlative. I have yet to see any data on such a product which makes any sense, and so you are probably paying more for something that brings no benefit. The most important thing about a coil is that it is of the correct type, and of good quality.

The most common electronic ignition systems operate in a similar manner to points in as much as the coil is switched on for a fixed angle which is called the dwell, and these systems are designed to work with a points type coil. This means that the coil is switched on for much longer time at low revs, so to avoid excessive current, the coil, or in the case of the stag, coil plus ballast must have around 3 ohms total resistance.

However, there are more advanced electronic ignition systems that have a variable dwell, and these are designed to work with special low resistance (impedance) coils. These coils are often called electronic type coils. They allow a very fast charge to get more energy into the coil at high revs, and are especially beneficial on multi cylinder engines of 8 cyls and higher. But beware: dont fit these special coils to the simple fixed dwell ignition because they will overheat and will soon fail.

[Staggard]

Many Triumph owners opt to replace their standard coil with the Lucas Sport coil, to get a hotter spark. Often, though, they neglect to bypass the ballast resistor, used on some of the later models. Failure to do this will negate the benefit of using the hotter coil, as the Sport coil is designed to be used without a ballast resistor. What is the difference between the two types of coils?

Basically, a non-ballast coil is designed to produce full spark output with 12 volts on the input (+ terminal). A ballast coil is designed to produce the same spark output, but with only 6 to 9 volts on the input.

With a non-ballast coil, the input to the coil is the same, 12 volts, whether the engine is running, or being cranked by the starter motor. With a ballast coil, the starter relay1*by-passes the ballast resister when the starter motor is spinning the engine, and applies the full 12 volts to the coil. Since the coil is designed to provide full spark with reduced voltage, the application of the full 12 volts produces a much hotter spark, which is an aid in starting. After the engine starts, and the starter motor is off, the coil voltage is dropped to the lower voltage, and the coil output is the same as for a non-ballast coil. The reason the ballast type coil is not run at the full 12 volts, for a hotter spark, is to prevent damage to both the coil and the points.
Hope this helps . Sometimes it hard to grasp things and get a full understanding as certain words can be taken or misunderstood .
I found this explanation on the net it's basically the same as what's been said but may help some trying to understand .

Ignition Coil Sports Type DLB110

£14.02 INC VAT Lucas Sports Coil 6Volt for use with a ballast resister or ballast wire as generally found on Mk2 Cars. These sports coils when used with Sports Electronic ignition, like for example Lumenition Performance Magnetic as opposed to standard Lumenition Optronic systems, can be asked to produce higher high tension voltage than standard. They will produce up to 40,000 Volts. To achieve this the spark plug gap is opened to 40K This can improve performance Normal coil output is 25,000 volts. The ignition leads sold on this site can handle up to 30,000 Volts. If you wish to use the full 40,000 then it is wiser to invest in some ignition leads suitable for purpose. We are also advised that it is likely the Rotor Arm and Distributor cap will need replacing more frequently when used with extra wide Spark plug gaps. NOTE Why a 6 volt coil in a 12 volt car? With the points closed, current will flow as follows: battery to ign switch to ballast resistor to coil to points and finally to ground. With an assumed charging voltage of 14 volts at the battery, we can measure voltage drops of about 8 volts across the ballast and 6 volts across the coil. THIS MAKES THE COIL OPERATE ON 6 VOLTS WHICH INDICATES THAT IT IS A SIX-VOLT COIL. But why have a Ballast resistor? To stop points or Electronic seeing too much voltage and burning out. However it is "by passed" by direct supply from the starter solenoid during engine start meaning a full 12 volts is applied to the coil increasing the spark voltage for quicker fire up. Lucas 6volt sports coil sold by LD parts

[stag157.7]

Ignition Coil Sports Type DLB110

£14.02 INC VAT Lucas Sports Coil 6Volt for use with a ballast resister or ballast wire as generally found on Mk2 Cars. These sports coils when used with Sports Electronic ignition, like for example Lumenition Performance Magnetic as opposed to standard Lumenition Optronic systems, can be asked to produce higher high tension voltage than standard. They will produce up to 40,000 Volts. To achieve this the spark plug gap is opened to 40K This can improve performance Normal coil output is 25,000 volts. The ignition leads sold on this site can handle up to 30,000 Volts. If you wish to use the full 40,000 then it is wiser to invest in some ignition leads suitable for purpose. We are also advised that it is likely the Rotor Arm and Distributor cap will need replacing more frequently when used with extra wide Spark plug gaps. NOTE Why a 6 volt coil in a 12 volt car? With the points closed, current will flow as follows: battery to ign switch to ballast resistor to coil to points and finally to ground. With an assumed charging voltage of 14 volts at the battery, we can measure voltage drops of about 8 volts across the ballast and 6 volts across the coil. THIS MAKES THE COIL OPERATE ON 6 VOLTS WHICH INDICATES THAT IT IS A SIX-VOLT COIL. But why have a Ballast resistor? To stop points or Electronic seeing too much voltage and burning out. However it is "by passed" by direct supply from the starter solenoid during engine start meaning a full 12 volts is applied to the coil increasing the spark voltage for quicker fire up. Lucas 6volt sports coil sold by LD parts

or fit cdi ignition and not worry about coil voltage
Duck
Alan

[V Mad]

Some relevant points there. Regarding the Lucas DLB110, if the claims are true that the output voltage is increased, that may not be a good thing. It does not necessarily translate to more spark energy, and the higher voltage may cause problems with tHT tracking. You can uprate the leads, but the rotor arm and dissy cap is old school and may not take the additional stress without breaking down. Getting a good spark is all about first charging the coil with sufficient current. That is easy at low revs, but as revs go up there is less time available to charge/discharge it. A higher voltage coil would have more inductance, which means a longer charge time, so it would be worse at the higher revs.

Incidentally, the Lucas website lists the DLB102 and DLB105 coils for the Stag, but has no information, that I can find, about the products, not even a description. These days it seems that Lucas is just another purchased brand name.

The CDI ignition that Alan mentions is a completely different system that doesnt require charging of the coil with current. It uses a capacitor to charge, and then dumps the voltage into the coil. So the coil works as a transformer rather than an inductor. They are not popular in the UK, but the Americans seem to like them. I built my own CDI system in 1968, and fitted it to my GT Cortina.

[KOY 23]

A lot of Mercs are cdi, there is a badge on the back to prove it.

[pagan]

A lot of Mercs are cdi, there is a badge on the back to prove it.

And air conditioned too..

It's tagged "Kompressor"

[Mike Stevens]

then dumps the voltage into the coil.

Strictly speaking Chris, it dumps the charge or energy into the coil, but that is being really picky!

I remember making those back in the early 70's. 400V DC from a 4 uF capacitor connected across the coil via a thyristor. You kept your fingers out of that box for sure!

Cheers,
Mike.