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Flashing the field w/magneto-no battery

Electrical issues
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Flashing the field w/magneto-no battery


Post by DJ » Sat Jul 03, 2004 8:03 pm

Is it necessary? and if so, how? The absence of the battery seems like a problem. I would not dare to try it when the bike is running. Any thoughts? Weez? Anybody?

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Re: Flashing the field w/magneto-no battery


Post by Jack_Hester » Sat Jul 03, 2004 10:21 pm

DJ -

Interesting thought. If no battery, makes you wonder how it is staying polarized. Hopefully, residual magnetism will keep it polarized and generating. Without the battery, I don't know how you can depend on it, though. I'm sure someone has figured a solution to make sure that it always generates.


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Re: Flashing the field w/magneto-no battery


Post by Cotten » Sun Jul 04, 2004 3:22 am

Dammgood question!

In all my years, I have only my own batteryless project for experience, ... and I only trusted to luck to polarize with a battery on the ground beside the bike.
Thanks to a blue-hair who took me out on another scoot, this project has been in cold storage without a good test of its electrics,....but I shall need to know what's proper,...soon.... I hope.


Re: Flashing the field w/magneto-no battery


Post by DJ » Sun Jul 04, 2004 12:05 pm

I had planned on running a battery, (12volt system), but got to thinking I might like the dim lights at low idle.......it screams VINTAGE.....or magneto custom at the very least. And I'm sure a quart of beer would sit right down in the hole. Maybe a 40 0z....(solo seat) ;D
The other alternative to a no battery setup with a mag is one of those capacitor battery eliminator doo-hickies, that gives you constant light and I'm wondering if that wouldn't hold the polarity of the gen,.....it seems there should be some mention of flashing the field in the capacitor installation instructions...(but I'm not holding my breath on that one).
On the way home from the garage earlier, I also had the idea of simply using a battery with suitable gauge leads w/clips to flash as Cotten mentioned.
The Mag/No battery setup is used all the time, and there must be a failsafe way.


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Re: Flashing the field w/magneto-no battery


Post by kell » Sun Jul 04, 2004 7:47 pm

"Battery eliminator" = ripoff
-- that is a capactor they will charge you 20 or 30 bucks for that you can get for a fraction of the price from an electronics supply house. Or free, desoldered off old junk circuit boards. I peeled the label off a White Bros. "battery eliminator" and it is merely a 4900 uF 50 V capacitor. If you can find a capacitor with at least a few thousand microfarads (uF) and rated for thirty volts or more it's gonna work.
As for flashing the field you don't need a big heavy battery just to flick a spark at the generator field for a split second. I bet you could just carry a little 9 volt battery when out riding. In case.


Re: Flashing the field w/magneto-no battery


Post by DJ » Mon Jul 05, 2004 12:33 pm


Man, I've gotta believe everything you say about electrics....
I've seen your bike!
Thanks for the specs on the capacitor. White Bros. just has a colored can or label on it and they figure they can charge for their clever idea. I might give the discount item a try.
The 9 volt battery would seem to definitely work on a 12v generator, because a 12v would have spikes and dips in that range in the first place, but I figure I'll zap it once with a 12v charger at low amps in the shop, and hope for the best. And I think Jack hit it on the head about residual magnetism keeping the polarity from then on in the generator/regulator circut. It's only if anything gets disconnected and reconnected after that...it would have to be done again.
One of these days I'm going auto advance with a battery, but for now I've got to work with what I've got and can get. I'm just planning....brainstorming....while disassembling and detailing everthing down to the lock washers and spacers on this '60 while the engine, trans and wiring is in the frame. I've got two weeks vacation and she's getting ready to go back together.

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