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Old 10-03-17, 10:14 AM   #1
Shifty1962
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Default Best type of Ignition coil/ballast to use

Hi all.
My Amanco has a weak magneto so is currently running using a coil and battery lash up. The previous owner however was no electrician and it all seems a bit Heath Robinson. In fact it started smoking so needs some attention.

I have a selection of fluorescent light ballasts (god knows why I kept them all these years) and was hoping somebody could tell me which type and/or rating would be best. I have some 75w 100w and 150w ballasts.

I am going to build the coil and motorbike battery into an old ammo box painted the same as the engine so it looks more presentable until I sort the magneto out.

Thanks Steve
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Old 10-03-17, 10:44 AM   #2
nickh
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If it's heating up to the point of smoking your battery isn't going to last very long!

I'm no Amanco expert, but I recall that there is a spring on the ignitor which should be moved when running on battery and coil. That done, the points will only close shortly before the ignitor trips enormously reducing the duty cycle, hence battery consumption and heating.

As for types of ballast coil, I have never found one which didn't produce a healthy flash when tickled across a battery but those old heavy ones about 6" long must be more robust.

NHH

Last edited by nickh; 10-03-17 at 10:49 AM.
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Old 10-03-17, 12:35 PM   #3
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Quote:
Originally Posted by nickh View Post
If it's heating up to the point of smoking your battery isn't going to last very long!

I'm no Amanco expert, but I recall that there is a spring on the ignitor which should be moved when running on battery and coil. That done, the points will only close shortly before the ignitor trips enormously reducing the duty cycle, hence battery consumption and heating.

As for types of ballast coil, I have never found one which didn't produce a healthy flash when tickled across a battery but those old heavy ones about 6" long must be more robust.

NHH
It started to smoke because the twisted wire connections with no fuse fitted shorted out in the biscuit tin that he had used. The battery and ballast were loose in the tin with nothing insulated properly.

The igniter spring is in the correct position holding the contacts normally open and when I metered the existing coil it draws about 1/2 amp when triggered.

I'm going to have a play and try each ballast to see which gives the healthiest spark. I'm guessing I don't want a full on arc welder type spark or the igniter contacts wont last long.

The idea of the ammo box was not only for aesthetic reasons but to also cool the ballast if needed by acting as a heat sink. I would only expect it to get warm after extended running but I have not had the engine running for more than 20 minutes and did not think of the coil getting hot.

This is all new to me and I'm enjoying the challenge.
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Old 10-03-17, 12:55 PM   #4
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Quote:
Originally Posted by Shifty1962 View Post
(snip) It started to smoke because the twisted wire connections with no fuse fitted shorted out in the biscuit tin that he had used.
Sorry, I misunderstood - thought ballast was getting hot in use!

NHH
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Old 10-03-17, 03:18 PM   #5
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Quote:
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Sorry, I misunderstood - thought ballast was getting hot in use!

NHH
No worries I should have been more clear. I knew what I meant but forgot only I could see what had happened.

Last edited by Shifty1962; 10-03-17 at 06:55 PM.
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Old 11-03-17, 03:08 PM   #6
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So after some experimenting and some semi scientific measuring with my multi meter I have decided to use a 75 watt ballast as my spark coil.

Using the meter in series with the ballast and connecting directly to the battery terminals the 75w draws 0.45A, the 100w draws 1.12A, and the 150w a huge 1.81A at 12volts.

I used two four inch nails as the spark gap touching one nail point to the flat head of the other and observed the spark as they were pulled apart. I only got one jolt and it made my eyes light up I can tell you

There was no apparent difference in the intensity of the spark between the six ballasts I tested so it makes sense to use the one that draws the least current. I have two of each type and the readings were pretty consistent for like rated ballasts.

The above is just my findings while playing for half an hour so it is by no means conclusive. I hope it is of interest and possibly of use to somebody.
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Old 11-03-17, 03:19 PM   #7
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Definitely of interest - I've never tried anything that scientific so thanks.

NHH
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