battery ignition vs. alternator ignition

[rtpassini]

is the difference between a battery ignition and an alternator ignition is the stator?
obviously cars use alternators. so they would be alternator ignitions? and things like motorcycles and outboards that have a stator, are battery ignition?

 

[Silvertip]

Re: battery ignition vs. alternator ignition

You are wrong on both examples. Ignition systems that require a battery do not have stators -- they have distributors just like your car -- or at least like your car used to. Stators on an outboard are located under the flywheel. Magnets in the flywheel passing over the stator poles generates the electricity need for the engine ignition system. The battery is used only to run the starter and any accessories on the boat. When it is mentioned that an outboard has an alternator, it is not generally a separate alternator like you find in a car. It is also part of the stator. The output of those stator windings feeds a rectifier that feeds a voltage regulator (usually) which charges the battery. Hope that clarifies things for you. Your bike will have a magneto ignition and there is no such thing as an alternator ignition.

 

[rtpassini]

Re: battery ignition vs. alternator ignition

You are wrong on both examples. Ignition systems that require a battery do not have stators -- they have distributors just like your car -- or at least like your car used to. Stators on an outboard are located under the flywheel. Magnets in the flywheel passing over the stator poles generates the electricity need for the engine ignition system. The battery is used only to run the starter and any accessories on the boat. When it is mentioned that an outboard has an alternator, it is not generally a separate alternator like you find in a car. It is also part of the stator. The output of those stator windings feeds a rectifier that feeds a voltage regulator (usually) which charges the battery. Hope that clarifies things for you. Your bike will have a magneto ignition and there is no such thing as an alternator ignition.

i knew most of that. (at least with the stator, having replaced a few of them)
the reason i ask, is because the CDI instructions vary between ignition types
http://www.cdielectronics.com/Portals/0/installsheet/414-2770.pdf

i was told that i have a battery ignition. but i was wondering how you can tell the difference.

 

[Chris1956]

Re: battery ignition vs. alternator ignition

Silvertip, While what you have stated about battery-driven ignitions having distributors is correct, that was a design decision, based upon cost, not physics. Merc built their battery-driven cdi ignition systems with a distributor and a single switchbox. They could have easily built a battery driven CDI system with seperate coils, triggers and switchboxes, and not used a distributor. Also, on the battery-driven CDI systems, Merc used a stator and a rectifier to change the battery. Battery charging was completely seperate from the ignition, however, the source of the battery charging voltage and current came from the stator under the flywheel and the flywheel's permanent magnets.

The newer Outboard ignition systems use a combo stator that supplies voltage to run the ignition system switchboxes or power packs, as well as charge the batteries via rectifier or voltage regulator. At least one outboard that I know of has an external automotive-like belt driven alternator, but the vast majority use stators for both purposes. Also, my '98 150HP Johnny uses battery voltage to supplement the stator voltage to the powerpacks during starter cranking. After the motor starts. only the stator powers the ignition system.

 

[Silvertip]

Re: battery ignition vs. alternator ignition

You can certainly have a battery ignition and still have a stator, but in the case of the stator, it is likely used to only charge the battery -- it would not have anything to do with the ignition since it would be powered from the battery. The stator in this case replaces a separate alternator. The key in this discussion is that if the engine will not run without a battery, you have a battery ignition. If a battery is not required for the engine to run, then you have a magneto ignition. CDI merely means that the ignition system is a capacitor discharge design and those can be used on any engine whether the ignition system is battery or magneto driven. One thing you DO NOT want to do is disconnect the battery from a running engine as that will likely fry the rectifier and possibly damage the CDI unit if the engine is a battery ignition type. To tell whether you have a battery or magneto ignition, you would need to understand the wiring of your engine but one clue would be as follows:
If the CDI unit has +12V (probably a red wire) that is active only when the key is on, that would indicate a battery ignition. A CDI box for a magneto system would have a number of wires exiting from under the flywheel and then to the box but there would be no +12 feed to that box since it is the stator that provides the power it needs.

 

[F_R]

Re: battery ignition vs. alternator ignition

rtpassini, have we confused you yet?
Assuming you have a Johnson or Evinrude, with CD (capacitor discharge) ignition, there are two general types:

Battery CD. The electricity to power it comes from the boat battery. An alternator is used to recharge the battery, but has nothing to do with the ignition system. A battery CD system has one spark coil and a distributor to direct the spark to the proper cylinder. The distributor may be under the flywheel or it may be timing-belt driven.

Mag CD, probably what you are referring to as alternator ignition. This type is powered by special coils on the alternator stator, instead of the boat battery. There will be a separate spark coil for each cylinder and no distributor. The boat battery has nothing to do with the ignition system on this type. It will run with a totally dead battery by hand starting it.

So.o.o.o., the quick and easy answer to your question is does it have a distributor cap, or does it have separate coils? That will tell the story.