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'Field excited' alternators - any available?

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I want to replace the OEM Lucas alternator on my '74 Commando MKIIa. Am considering the 3 phase SPARX kit. However before I move forward is anyone aware of a field excited alternator system that is available.

See here for a useful primer on many things electrical used on bikes and other toys. He describes in general terms what a "field excited alternator" is.

Also I welcome any experienced feedback on the 3 phase SPARX system including the best, most cost effective, place to purchase the SPARX.

Thanks,

Ron Wellman, Midland MI USA, rawellman1216@gmail.com, 989.600.8581

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The sparx 3 phase regulator will have a hissy fit and overcharge unless you fit resistor plugs so best avoided. Current Lucas alternators are rebadged Wassels are they bought the rights to the name. My advice is to instead of increasing the output drop the load with LED bulbs including H4 dipped.

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Previously john_holmes wrote:

The sparx 3 phase regulator will have a hissy fit and overcharge unless you fit resistor plugs so best avoided. Current Lucas alternators are rebadged Wassels are they bought the rights to the name. My advice is to instead of increasing the output drop the load with LED bulbs including H4 dipped.

Thanks John for the detail re: resistor plugs. I had heard that using the SPARX 3 required resistor plugs but now I know why.

It's a high wattage headlight that I would like to use, the original Lucas 45-50w bulb is anemic. I would like to use a quartz halogen. Considered an LED headlight but those bright enough and currently available are expensive and complicated with required heat sinks. Some even have cooling fans that would be needed to fit inside the headlamp housing.

I am additionally considering just replacing the OEM rectifier and zener diode system with a modern solid state rectifier with included voltage regulation. I have an inquiry in to Rick's Motorsports Electrics to see which of their products might be suitable.

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I have a Lucas single phase (RM21 I believe) on my Atlas. It quite happily powers a 60/55 QH headlight plus heated handlebar grips so I see no compelling reason to go 3 phase. The load from your coils is unlikely to be significantly more than from the heated grips so you should be fine. I did fit an LED stop/tail light for no better reason than it's nice and bright.

P.S. for some years my wife ran a Guzzi T3 with a field excited Bosch 3 phase generator. It was a bit prone to be unexcited and stop charging. Probably down to the spaghetti wiring.

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Considered an LED headlight but those bright enough and currently available are expensive and complicated with required heat sinks. Some even have cooling fans that would be needed to fit inside the headlamp housing.

I have one of these fan cooled LED's fitted to a 5 3/4" headlamp shell, its tight but its in there and working.

But there are alternatives that use stainless mesh for the cooling which are much easier to find space for.

http://www.aliexpress.com/item/2015-Milan-5000LM-fanless-40w-fish-tail-6000K-H4-led-best-for-motorcycle-head-lamp-light/32560348196.html

or

http://www.aliexpress.com/item/Lowest-Sales-Price-2x-H4-Hi-Low-Beam-CREE-COB-LED-8000LM-Set-White-Car-DRL/32558103725.html

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I have tried an LED BPF replacement headlight bulb - very bright, low current use, poor focus - not terribly useful at night.

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I'm with Gordon on these led bulbs. They don't give a very useful beam. By fitting two relays in the headlight circuit you can avoid the voltage drop to the headlight bulb that is caused by the feed passing through ignition switch, headlight switch and dip switch.

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I have heard that the quartz halogen bulbs get so hot that the silvered (chromed?) lining of the reflector will be degraded.

I am sure that someone with experience on this will let us know.

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Previously michael_sullivan wrote:

I have heard that the quartz halogen bulbs get so hot that the silvered (chromed?) lining of the reflector will be degraded.

I am sure that someone with experience on this will let us know.

Thanks for the heads up, a consideration I had not thought of. Let's see what others say.

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Previously Gordon Johnston wrote:

I have a Lucas single phase (RM21 I believe) on my Atlas. It quite happily powers a 60/55 QH headlight plus heated handlebar grips so I see no compelling reason to go 3 phase. The load from your coils is unlikely to be significantly more than from the heated grips so you should be fine. I did fit an LED stop/tail light for no better reason than it's nice and bright.

P.S. for some years my wife ran a Guzzi T3 with a field excited Bosch 3 phase generator. It was a bit prone to be unexcited and stop charging. Probably down to the spaghetti wiring.

I assume my alternator also is the RM21 Lucas as originally fitted.

Other members have reported that the Boyer Brandsen ignition consumes a lot of power. That surprises me as I believe it's a solid state device and the coils used are the same as those originally fitted. Coils are coils and their energy consumption should be independent of whatever is energizing and switching them off to produce the high voltage side.

The headlight bulbs in the attached photo are both marked 45/40w. The one on the right was in the bike when I bought it and is NOT adequately bright, I haven't tried the more rounded one on the left.That said I need to check the voltage actually supplied to the bulbs. May find that the dim bulb is due to low voltage and not just a low wattage bulb?

Attachments nortonheadlightbulbs-jpg
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The bulb on the left has the correct fittings for an H4 replacement. Stick one in and try it. I've used H4s for many years now and have had no problem with reflectors fading. Heat shouldn't be a major problem upping from 50/40 to 60/55 watts.

As you are no doubt aware, BFP and H4 bulbs do need different reflectors. One advantage of H4 bulbs is that every filling station has them on the shelf. Quite useful if a bulb dies when you are out.

One other alternative is to try a sealed beam unit, as used in old-style minis and black cabs.

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I don't think either of those two bulbs will fit an H4 reflector. The one on the right has the correct wiring plug but not the correct locating ring/fittings

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Boyer Bransden ignition does NOT consume significantly more electricity that std coil ignition. The early RITA AB5 does, it used twice what the ABII later ignition used. And of course the ABII uses almost the same as STD coil ignition.

If you must use an H4 and want best lights then it must be used with its designed reflector, just adding an H4 to any old reflector will still not give you best lights. IF there is a voltage drop due to poor switching and wiring then of course fit a couple relays which are switched from the original headlamp circuitry. But measure the voltage drop at the headlamp first on BOTH wires to the headlamp bulb.

Hi Gordon I like you doing my job on here.

AL Oz

 


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