Vitesse said:

Yeah I am pretty sure with that dry twin coil wasted spark setup it does need a ballast resistor. I am sure I have read it somewhere. I will see if I can find out where, probably the fiat club uk forum.

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I think you're correct Tony. I read that there are some 126's in which part of the length of the cable that supplies the low tension to the coil is resistive in itself, which cleverly provides the voltage reduction.
The odd thing is that if you simply put a resistor in series with the supply, you lose part of the advantage of having a coil that works at less than 12v. That advantage being that when starting, especially from cold, the voltage drop caused by the starter still allows the low voltage coil to function well. So in a perfect situation, there should actually be a second supply to the coil which bypasses the resistor when actuating the starter.
Interesting info on the link.
http://webshop.fiat500126.com/katalog/artikelinfo/1707/twin-ignition-coil-_cornered
Smurf's coil has 12v stamped on it; as keeps cropping up with all the discussions about charging systems, it seems that the actual voltage running around in the car can be around 14v for most of the time and perhaps that is why the coil needs a resistor?
Where are all the experts when you need them???

Yeah if you type ballast resistor into the Fiat Club UK forum there are lots of post regarding it, apparently Brian Rylance wrote something up on it. All the posts seem to indicate that the one set that does need it is the dry wasted spark coil that has no distributor cap.

There are comments that suggest that the dry coil works better and starts better when the voltage is dropped to about 10V's, hence why Smurfs is stamped 12v which is probably the max. As you say if you have an alternator then your likely to be pumping out 14+V so you need a ballast rated at about 1.5Ω.

In fact I have just looked on the Axel Gerstl website to see how much a replacement coil is and guess what, even comes with a little picture on how to connect it up. Read the comments.

http://webshop.fiat500126.com/katalog/artikelinfo/1707/twin-ignition-coil-_cornered

Also don't buy the resistor from AG or Ricambio etc you can get them on eBay for £4!!!! http://www.ebay.co.uk/itm/261319911135

Hi there,

sorry if I'm teaching granny to suck eggs but ....
Ballast systems were introduced in the early 1970's to help cold starting.
A standard ignition coil is rated at 12V and has a low tension (contact breaker side) resistance of 3 ohms.
A Ballasted coil is rated at 6V and has a LT resistance of 1.5 ohms.
Under normal running conditions a ballast resistor of 1.5 ohms is connected in series with the coil so that the actual voltage at the coil is 6V ( the resistor produces a 6V voltage drop.
When you turn the ignition key to start, the Ballast resistor is effectively short circuited so the battery voltage is applied fully across the coil.
This means that in extreme cold conditions and with a less than perfect battery, the coil will still produce a healthy spark because it will have somewhere between 9 and 12v driving it. The coil will not be damaged because you normally only spin the motor over for a number of seconds when starting.
When you release the ignition key to the normal running position once the engine has fired, the ballast resistor is put back in series with the coil so it runs at it's normal 6V.
Your coil is marked 12V so it is not a ballast system, it looks like a lost spark coil. Ballast resistors are chunky ceramic resistors ( to handle the heat dissipation) about 40mm long and are normally positioned near the coil to lessen voltage drop in the system.
The resistive leads you are talking about are HT leads that use resistive cores to lesson interference.
Do you have a multimeter ?

Richard

That's the kind of expert I mean. All my bits of half-knowledge sorted out and my eggs pre-sucked for me.
Axel Gerstl, who supply these provide the following diagram and recommend the resistor to protect the coil. Not the true ballast system as Mattsdad describes but it looks like the whopper that I used to have in my 126 BIS. This was actually fitted in the front wheelwell and possibly kicked out quite a lot of heat.
http://webshop.fiat500126.com/katalog/artikelinfo/7659/series-resistor-for-twin-coil

Hi, I have a lost spark type ignition system on my 126 powered Gamine and my 126. Both coils look like a standard coil with 2 HIT leads coming from the top, I haven't seen any for sale but I found this which looks very much like your coil. I don't know if all coils this shape require the balance resistor or not as I have no experience of these. Is there another member reasonably close to loan you a coil to see if this solves your problem? Oops I didn't see Peter's post

Ralph

http://webshop.fiat500126.com/katalog/artikelinfo/1707/twin-ignition-coil-_cornered

fiat500 said:

That's the kind of expert I mean. All my bits of half-knowledge sorted out and my eggs pre-sucked for me.
Axel Gerstl, who supply these provide the following diagram and recommend the resistor to protect the coil. Not the true ballast system as Mattsdad describes but it looks like the whopper that I used to have in my 126 BIS. This was actually fitted in the front wheelwell and possibly kicked out quite a lot of heat.
http://webshop.fiat500126.com/katalog/artikelinfo/7659/series-resistor-for-twin-coil

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I understand what Mattsdad says but I don't think a true ballast setup as he describes was ever installed on a 126 but I may be wrong???

Maybe the term ballast is what is confusing the issue. From what I can see it's just a resistor that sits on the +VE from the ignition switch, so it is in series constantly and rated at 1.5Ω and would drop 14V's down just below 10V's.

It seems odd that Axel Gerstl would recommended it for a twin wasted spark coil if it isn't needed???? It maybe simply the case that due the fact it is dry that is can't handle as high a voltage as an oil filled one, therefore is more prone to overheating and burning itself out????

hi there I am quite new to the forum, I do not have a wasted spark system on my car but I am sure I have seen a ballast resistor fitted at the front of some of the cars I have looked at. May have been by the fuse block it was certainly in that compartment area. Not sure if this helps.

Hi there,

to check whether an ignition coil is ballasted or not, turn on the ignition and check the voltage at the positive terminal of the coil. If it reads 6V then power is being fed through a ballast resistor. If the key is turned to the start position, the voltage will rise to 12V to boost the coil at starting and will then drop back to 6V once the key is released back from starting to the normal running position.If there is 12V at the coil in the normal running position then it is on a direct feed from the battery. A ballast resistor is always next to the coil because the voltage is being dropped down to 6V to feed the coil and you do not want any further voltage drop to the coil because of a long wiring run.
Regarding the 14V - when cars first had batteries they were composed of 6 cells. A lead acid cell fully charged with a good electrolyte has a potential of 2.2V so the 6 cells in a battery gave it 13.2V. However this is a maximum voltage. To make calculations easier it was decided that a 10% voltage drop was considered an average figure so a "standard" figure of 12V was used to identify ratings. The 14V comes from the alternator since it needs to provide a 1 to 2V charging "head" above the battery to charge it.
I will send out a separate post to help identify the ignition problem as I have rambled on long enough on this one.
Richard

Hi folks,
thanks for all the info !
Some of which is flying over my head, however I think I got the gist of it, so I think the way to go is replace the coil and get the resistor, which I also saw in AG.

Is it strange that it has worked perfectly fine up until now ?

I don't have a multimeter but will try and pick one up , I will be back on to Richard about how to use it !

I presume it will be fine to fit the resistor beside the dry coil in the engine bay ?

Must have read these posts about 10 times today trying to get it into my thick skull !

Peter, Tony, Richard, Ralph etc
Appreciate your help.
Thank you
I will report back
Darryl

Newsflash !
Replaced coil and inserted spark plug testers.
Started almost immediately ! I have to say the little fella sounds different, in a good way !
Lights flashing in spark testers of course.

Went for a five minute spin.
The battery light would no go out on the dash, usually gone if you give a little rev.

Also, not sure if it is connected but usually when I turn the engine off the battery and oil light come back on and I have to just turn the key to start the engine again to turn them off. The guy I bought the car off said it had something to do with "electronic ignition" ?
Also if you did not do this it would drain the battery.
Now, when I turn it off the lights do not come on and obviously too early to see effect on battery.
Any ideas ?
I drive you lot nuts solving one thing only to dump something else out there !

So I have the resistor and I got a multimeter.

Richard I was hoping you could tell what to attach where to test the voltage on the coil, before going ahead and fitting the resistor.

Really, I cannot express how pleased I am that I got this far with your help ! I know it is probably stuff you guys do in your sleep.

I have included a photo which sums up my current euphoria !

dk500 said:

.

Is it strange that it has worked perfectly fine up until now ?

I don't have a multimeter but will try and pick one up , I will be back on to Richard about how to use it !

I presume it will be fine to fit the resistor beside the dry coil in the engine bay ?

Click to expand...

Just in case it still is working OK I would calmlygive it one last attempt. Charge the battery, check the points again including the timing, double check the all the wire connections and that the choke is operating fully.
Just try it two or three times to be certain.
I got this cheapo multimeter a few years ago and it has served me well. The continuity setting, which buzzes when there is a circuit allows me to set the points timing with the ignition turned off...it just lacks little crocodile clips which is annoying: http://www.toolstation.com/shop/p98689?table=no

Sticking the resistor at the coil end of the supply seems to make sense.

We'll need a little video of the engine once it's going again.

Good to hear you got her or him started again Darryl.

So on the other problem with the warning lights. How do you start the car, manually with the lever, key, push button?

Are you saying you turned the engine off and if you pulled the key out and walked away the warning lights would stay on? Then to cure it, you start the engine let it run then switch it off and the warning lights have gone out? The guy you bought if said it was down to electronic ignition, that you don't have?

You may have inadvertently fixed that issue, as Peter says battery probably needs a decent charge and hopefully that will cure the generator light problem but it's encouraging that it started well with a potentially not fully charged battery.

dk500 said:

The battery light would no go out on the dash, usually gone if you give a little rev.

Also, not sure if it is connected but usually when I turn the engine off the battery and oil light come back on and I have to just turn the key to start the engine again to turn them off.

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We share your euphoria in getting the little blue bullet to fire again. Did you mean that you fitted a new coil? Quick work in getting one if you did.

As for the light(s) on the dash, my initial thoughts are that the alternator circuits/diode are faulty and allowing the battery voltage to pass back to the ignition switch/lamp. Well out of my comfort zone but I'm sure the collective will work on it.

I would avoid running the car until you have the answer to resistor or no resistor? Also, for now, disconnect the negative terminal of the battery whilst you're not using the car to avoid damaging the new battery and possibly the coil.

Hi, glad to hear the wee car is up and running, hope the battery charging solves the ignition light problem, if not I'm sure there is someone here that will help to solve the problem.

Ralph

Hi
Just giving some answers from the last two posts and asking a few (alot) more :

I start the car with the key.

If I turn the engine off and remove key the dash lights stay on and the battery drains.
To cure it I just turn the key to start and off again - the dash lights go out.

Would the battery need a charge , it is only a week old ? Can I check the battery with the multimeter ?

I thought the generator light only indicated that there was sufficient charge being produced to recharge the battery as opposed to the current charge level of the battery ?

I did replace the coil.

I will try the multimeter on coil later, could you advise, red on meter to + on coil and black on meter to bodywork for earth ?

I will disconnect the battery.

Anyone with info on testing alternator ?

Thanks
Darryl

The answers that I feel reasonably competent on Darryl.
Your new battery might have take a bit of a hammering with all this and even when brand new isn't necessarily at optimum charge level. Ideally charge it out of the car or with the battery terminals removed to avoid damage to electronics.
The red charging light shows that the alternator or dynamo is not currently putting out sufficient current to charge the battery; it does not tell you anything about the state of the battery. On tickover with a dynamo it is likely to light up as it will whenever the engine is not running and the ignition is on.
Although you may actually have a faulty ignition switch, crossed or misconnected wires, bad earths or other faulty electrical components, the ignition light being on when you turn the key to "off" may mean that the battery is losing current in reverse back to the generator implying a fault with the cutout device.
Have you read the "sticky" on generator fault-finding by Mattsdad? I'm sure he will guide you through testing the ohms rating of the coil which I believe would be the guide as to the need or otherwise for the resistor.
I will try to think the fault-finding through on this one.:bang::bang::bang:

Hi Darryl,

I did a write up on basic fault finding which is in the sticky on the front of the classic posts - car electrics and fault finding simplified - which might shed light on how you trace faults.
Regarding your Ignition Warning Light(IWL) staying on when you turn the key to the OFF position and only going out when you turn it ON then OFF again points to a faulty Ignition Barrel/Switch.
The Ignition Switch completes the connection from the Alternator, through the IWL to the battery so when you first turn the key it lights up because it has 12V from the battery on one side and an earthed connection through the alternator windings on the other. Once the engine is up and running the output from the alternator reaches battery potential so the light goes out.
What I think is happening is that the first time you turn the key to off it doesn't move the the switch arm internally inside the barrel to fully disconnect the circuit. The next time you turn it, it moves it enough to make the disconnection (then again I could be totally wrong).
I have never in my 50 odd years of electrical engineering ever come across an ignition module giving the fault symptoms you describe. The ignition switch also disconnects the ignition circuit as well as the IWL.
I don't know why you need a resistor for the ignition coil feed if it is not a ballasted system - did the company you were buying it off explain it's purpose ?
I'd be interested to know what it's for as I usually work on 4 cylinder engines not twin cylinder lost spark jobbies
Richard

Hi Richard
I have printed out and actually bound your sticky, you are now a published author !
Actually just messaged Peter as I am trying to figure if I have dynamo or alternator!

Regarding the warning light staying on, this was the case prior to replacing coil , battery etc

This does not happen now, but the "battery" light is remaining on while driving, where usually it goes out once the car is revved or drive 3 or 4 meters.

Regarding the resistor. No information from the supplier and it is not fitted yet. I bought on the basis that I check the voltage at the coil while starting the engine as you recommended.

I did get a multimeter and was going ask you which probe goes where to get voltage at coil !
Is it correct to set ?
DC 20volts
Red probe to + on coil
Black probe to earth-car body

Apologies if my posts are a bit hit and miss !
Thanks
Darryl

MATTSDAD said:

I'd be interested to know what it's for as I usually work on 4 cylinder engines not twin cylinder lost spark jobbies
Richard

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Richard, regarding the purpose of the proposed resistor which I know was definitely fitted on the 126 BIS, there are various suggestions out there and none of them explain the why and wherefore to we non-electricians.
The Fiat 500 Club says that if the coil is specified at 1.5 ohms you need it, if 3.0 ohms you don't.
Some people say that its resistivity increases as is warms up, hence it is a very basic ballast system. The commonly stated value for it is 1.5 to1.7 ohms, which seems to follow at least mathematical logic to me.
So it might help clear things up if Darryl knew how to ascertain the rating for his new coil using the multimeter.
Regards, Peter

Hi,

if the resistor is 1.5 ohms then it is a ballast resistor to be used with a ballast coil.
The problem is that there are a couple of different types of ballast systems with different values for both the coil winding resistance and the ballast resistor.
They work as a matched pair to ensure that under normal running conditions the voltage drop across the ballast resistor presents the right operating voltage for the ballast coil.
To measure the primary resistance of the coil then take off the the connectors on the positive and negative terminals on the coil so there is nothing else connected. (take a digital photograph or make a drawing so you know which way round they were).
Set your multimeter to the 20 ohms resistance range and measure across the pos and neg terminals of the coil (polarity of the meter probes is not an issue when measuring across a coil).
If it measures 3 ohms or above then it is not a ballasted coil and should not need a resistor. If it measures 1.5 to 2 ohms then it is a ballasted coil and needs to have a ballast resistor in series when running to prevent it drawing too much current and overheating.
As I say I'm used to working on Lucas or Bosch systems so I can't say what they are for a 500 set up.
I converted my MGB from Ballasted to a non ballasted system where the ceramic ballast resistor was 1.5 ohms and the Lucas coil primary was 1.5 ohms.
I removed the ballast and fitted a 12V Lucas Sports Coil which had a primary of 3 ohms.
Richard
I'll write up a little paper on Ignition and Ballast over the next couple of days