Alt. conversion on H

DTK · Apr 22, 2013

Can I disregard the field resistor on the light switch and use
the starter side of the starter switch to excite the alt.? I am
using a mini alt. w /1 plug in connector and 1 hot post. Thanks
DTK.

mkirsch · Apr 22, 2013

The excite wire needs to be on a switch, otherwise it will run the battery down when the tractor isn't running.

I just run a wire from the + side of the coil up to a big diode, then on to the excite terminal in the alternator. Then the ignition switch also excites the alternator.

Sounds like you might have a magneto.

If you take power off the starter side of the starter switch, you will have to hold down the starter button, while the engine is running, until the alternator excites. Not good for the starter, in my mind.

I don't think there's any way around this, but to run a separate wire and switch to excite the alternator.

DTK · Apr 22, 2013

You are pretty sharp, I should have said its a magneto ign.
Should I leave the field resistor term. Unused ? Would the
momentary contact from the starter switch be enough to excite
the alt.? Thanks DTK

teddy52food · Apr 22, 2013

Simple & easist is to put a switch in the block where there is oil pressure. When the pressure comes up it closes the switch to excite the alt automatically.

Jon Hagen · Apr 22, 2013

Connecting the excite wire to the starter will not work well. The thing is that excite power to the alternator needs to be applied until the alternator is up to speed and charging. Their is that gap between when the engine starts, where you relkease the starter, and the time untill the alternator is up to speed and charging. Add to that,the Alternator excite terminal must not be connected to ground while charging. Having the excite wire connected to the starter windings would be a very good ground and would destroy the diode trio or regulator in the alternator very quickly.

Your best way to excite the alternator on a magneto equipped tractor is to use a normally open two terminal oil pressure switch in an engine oil gallery. Connect a 10 amp fuse to battery power and run it through the oil pressure switch to the alt excite terminal. When the engine runs and has oil pressure, the switch closes and excites the alternator. When the engine stops, it disconnects power to the alternator excite circuit. The 1980 chevrolet 6 cyl pickup engines used such a switch to power the electric choke .

DTK · Apr 22, 2013

Thanks for your help guys I"ll use an oil press. switch to excite the alt. DTK

charlieu · Apr 22, 2013

Here is a picture of an oil pressure switch that I use to excite the alternator when the tractor is equiped with a magento. I like putting the oil pressure switch in the oil line, up under the hood out of sight.

mkirsch · Apr 22, 2013

I like the oil pressure switch idea. Mentally noted for the next time this subject comes up.

John M · Apr 22, 2013

Make sure its a Normally Open OP switch. I cant think of the one I use, my parts guy always knows which one to get me.

Alt. conversion on H

DTK

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mkirsch

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DTK

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teddy52food

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Jon Hagen

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DTK

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charlieu

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mkirsch

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John M

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