9 replies to this topic

[minimalal]

i have a 1989 mini mayfair 998cc, bogo standard
mini garage recommened i got myself a new coil, so i just did and its got a ballast resistor, now i have no idea what this is and or wether i need it?? can someone just explain what it is and its function and do i need it?? i know nothing about electrics
any help appreciated cheers
alex

[dklawson]

There are a lot of threads on this topic that you can locate using the search function at the top of the page. There is a lot of reading available that will elaborate on the subject.

Succinctly, a ballast ignition system uses a couple of additional components to insure that the engine gets a hotter spark while cranking on the starter motor. In a "standard" ignition system the coil (+) terminal receives 12V power via a white wire from the ignition switch. Power leaving the coil on the (-) terminal goes to the distributor. When you crank the engine on the starter, the system voltage drops and the spark has reduced energy (it is "colder"). To compensate for this, a different coil is used on ballast ignition systems. The ballast coil has lower resistance to generate "hotter" sparks. However, if the ballast coil was used all the time, the additional current flowing through it would allow the points and other ignition components to burn up quickly. So, a simple control scheme is used, wire comes from the ignition switch to the coil (+) terminal through a ballast resistor which lowers the voltage and restricts current flow. A second wire (yellow/white) on the coil (+) terminal goes to the starter solenoid. When you crank the engine on the starter, the white/yellow wire bypasses the ballast resistor and delivers full system voltage to the coil so it runs "hotter". When you release the ignition key, the white/yellow wire is disconnected at the solenoid and power for the coil is supplied through the ballast resistor.

So that is what a ballast resistor is... an element to restrict current flow and lower the coil operating voltage during normal engine running. Whether you need a ballast coil or not depends on the year of your car AND what changes previous owners may have made. If you have a white/yellow wire on coil (+), look at the color of the OTHER wire there. If it is "pink" or white/pink, you need a ballast coil, but you do NOT need the external resistor. The pink wire IS a resistive element... the pink wire is a ballast resistor built into the wiring harness. If you only have a white wire on coil (+) and there is no evidence of a pink or white/yellow wire... you need a standard coil, not a ballast coil.

Finally, why did the garage tell you you needed a new coil. Coils seldom go bad. What symptoms was your car experiencing that they determined a new coil would fix it?

[Cooperman]

I once had to fix a Mini 30 on which the 'pink' resistance wire had melted and taken half the wiring loom in the engine bay with it. What a nasty and expensive job that was for the owner. Now I change those 9v coils for 12v, remove the 'pink' wire and replace it with a white one. It doesn't seem to have any effect on the starting or running, but it removes the risk of loom 'melt-down'.

[Cooperman]

If you want to keep the 'pink' wire, best to separate it from the loom and run it on its own, then if/when it melts-down it won't cause such carnage to the main loom.

[dklawson]

Most other manufactures actually fitted a resistor, but not rover they used a piece of restive wire. Which is fine when there new, but once they get a little corrosion on them it increases the resistance & thats why the melt the insulation and half your harness.

Rover is not the entity that made the decision about the resistance wire. It was common on BL cars. However, I agree that the pink wire seems like a strange way of providing the ballast resistance.

I'd like to add a footnote to the above about making the wire change suggested. If you run a "regular" wire to the coil (+) terminal, it should be "white" to agree with the "standard" color codes. If you run a regular wire to coil (+) it is 100% necessary to put the correct (standard) coil in place OR fit an external ballast resistor to your existing ballast resistor. You must not fit a regular wire directly to the (+) terminal of a ballast coil. Doing so will allow way too much current to flow and that will cause the points and condenser to fail prematurely. Also, if you don't use a heavy gauge supply wire... your new wire may melt.

The ballast ignition system is not complicated and DOES make starting easier, particularly in cold weather. Eliminate it if you wish but it was installed for your convenience.

[Cooperman]

Well, it's been really cold here for the last week and both of my Minis started fine today after not being started for a few weeks after putting the charger on them for 1/2 an hour each. Both have 12 v coils and original points-type ignition with much higher than normal CR's.

[dklawson]

The main reason car manufacturers changed over to ballast ignition systems, was cost and only cost.
With a ballast system they can use cheaper wire.

That is not correct. The spark plug wires are the same for either ignition type. The low-tension wire "type" is the same for both systems (excluding the pink wire). There are more wires in the ballast ignition system and ballast systems use a more expensive starter solenoid.

Cost was not the reason the ballast system was implemented. Ballast systems have more components and the total system cost is higher. Ballast ignition systems were used only for the purpose of making engines easier to start.

EDIT:
For a brief overview of ballast ignitions, see the link below (about 1/2 way down the page).
http://www.burtonpow...on_systems.aspx

[dklawson]

I'm sorry you had a bad experience with a ballast ignition system.

However, the only way too much current can flow through the low tension wiring in either ignition system (when the proper components are used) is if the coil end of the circuit forms a dead short to earth (since the ignition system is not fused). A ballast ignition system is not more likely to burn up wiring and it certainly does not cost less than a standard ignition system. I do agree that with more components in a ballast ignition system there are more parts that can fail.

[sheepy89]

Most other manufactures actually fitted a resistor, but not rover they used a piece of restive wire. Which is fine when there new, but once they get a little corrosion on them it increases the resistance & thats why the melt the insulation and half your harness.

Rover is not the entity that made the decision about the resistance wire. It was common on BL cars. However, I agree that the pink wire seems like a strange way of providing the ballast resistance.

I'd like to add a footnote to the above about making the wire change suggested. If you run a "regular" wire to the coil (+) terminal, it should be "white" to agree with the "standard" color codes. If you run a regular wire to coil (+) it is 100% necessary to put the correct (standard) coil in place OR fit an external ballast resistor to your existing ballast resistor. You must not fit a regular wire directly to the (+) terminal of a ballast coil. Doing so will allow way too much current to flow and that will cause the points and condenser to fail prematurely. Also, if you don't use a heavy gauge supply wire... your new wire may melt.

The ballast ignition system is not complicated and DOES make starting easier, particularly in cold weather. Eliminate it if you wish but it was installed for your convenience.

what would u class as a heavy guage supply wire?

cheers sean

[dklawson]

My experience with Lucas ballast ignitions is with MG-Midgets and Triumph cars. They used the same basic Lucas wiring scheme as Minis of the period. The main difference being that many of the Triumphs used an external ballast resistor instead of the pink resistor wire. Many GM and Ford products of the 1970s also had ballast ignition systems. They of course were not Lucas wired but they were nearly identical to the Triumph wiring with an external ballast resistor. The Canadians continued to import Minis to North America in the 1970s and they had ballast ignitions but I have not worked on one of those... in spite of the number of them that ended up "down here".