LED Headlight on 250 narrowcase "AC" bike.

[JimF]

I will try to make this story as short as possible.

I drew inspiration from this photograph to try and eliminate the headlight bucket.

DucatiF4.jpg

However, I am required by law to run with a headlight, day or night.

My headlight bucket contained only the headlamp, some wiring and an inacurate speedometer whose needle oscillated 5 to 10 mph either side of whatever speed it was trying to convey to me.

I could conceivably place a small-ish headlight in the triple tree if I used a LED unit of some kind.

LEDs use DC, I have an AC bike.

Ignoring all the drama regarding which rectifier/regulator to use, which winding to use, etc., I took a used Podtronics 1P (single phase 12-volt) that cost me $35 and installed it across the two alternator wires that are on the same coil and not internally grounded.

posdtronics 1P.JPG

The other grounded alternator winding still runs the ignition as 6-volts AC, and I am NOT running the brake light bulb in series with the coil.

The Podtronics needs a battery or a capacitor to develop output, so I added a big electrolytic cap similar to this:

big cap.jpg

I used a 58,000uF 15 WVDC capacitor only because that's what I had laying around.

The Podtronics lit up with 14.5 volts regulated DC.

My thanks go to Dew-Cat-e Bob for advice along the way...

Considering I am on one winding (one-half) of a 40 watt alternator, let's assume I have 20 watts on that one winding. In a perfect loss-less world I can figure that my 12-volts DC can only deliver about 1.5 amps (12 times 1.5 equals 18 watts.)

I had a 90mm Hella Projector low-beam lamp that I bought long ago to put in a race fairing I never bought for a project I never undertook.

hella1.jpg

The problem is the Hella is intended to hold a 12-volt H9 65-watt lamp, and with only 20-watts of power at my disposable that would never fly.

The second problem is the Hella unit is long with the projector and bulb socket attached together. The unit as supplied, even if I had 65-watts available, would extend out as far or further than the original headlight bucket and look twice as ugly and out of place.

hella2.jpg

I took off the socket which is the everything rearward of the black plastic in the photo.

One of the cool things about the Hella unit is a real glass optically ground magnifier mounted behind the lens.

hella3.jpg

I took my Hella 90mm apart by removing the bulb socket assembly.

I added one of my own triple Luxeon Rebel emitters fitted with white LEDs behind the optical glass.

BA15DHP.jpg

I mounted this up in place of the headlight bucket and as far recessed between the fork tubes as I could.

led1.jpg

From another angle:

led2..jpg

Here is the LED headlight operating in full daylight, which to my way of thinking is the litmus test:

led3..jpg

And another view:

led4..jpg

The engine is at idle RPM, but the light intensity is the same regardless of engine RPM.


Also I use the same LED but in red for the taillight.

The LEDs consume just 6-watts each so I am at about two thirds of my power budget.

I am thinking I could add a 12-volt DC GPS to the bike now!

Anyway, let me summarize:

The LED headlight is not legal as it is not DOT approved.

Where I live and ride headlamp use is mandatory, daytime too.

But consider this;

1) My legal 25-watt beam being powered by the 20-watt winding was nowhere near as bright as the LED.

2) My legal 25-watt beam would dim to 'firefly' mode when I came to a stop at night in the dark. I imagine the brake light did too. If a car approached from any direction at night I had to rev the engine in the hopes of bringing up the lighting so as to be noticed while I sat there in the dark.

3) I would 'overdrive' the 25 watt headlamp' beam somewhere between 30 and 40 mph. That is to say at that speed I was covering far more ground than the beam could safely illuminate ahead of me.

4) This non-legal setup gives me brighter street lighting at night than the legal lamp it replaces.

5) This setup makes me more visible at all times of the day to oncoming traffic.

6) This setup does not "dim" at idle in the darkness making me less vulnerable to being run over in the dark at a stoplight or stop sign.


So what I have opted for is increased safety in the form of brighter, consistent and not DOT approved over dangerously under-lit and DOT approved .


One of the reasons I incorporated the Hella H9 as the basic housing is that the DOT/SAE markings will tend to give the set-up an air of legal compliance should ever it be examined by a law enforcement agent. I could have and considered using just my LED assembly with no lens whatsoever as it would take up less space and be far less conspicuous, but any traffic stop would put me in serious jeopardy for incurring an additional ticket for not having a legal headlight on the bike as it would be quite obvious.


Without being able to leave the scene of the traffic infraction with an operational street legal headlight I could be stranded as I may have to leave the bike and arrange for a trailer home.


Only someone that understands the electro-mechanical aspects of incandescent and halogen lighting might realize that there is absolutely no bulb socket mounted behind and extending rearward from the lens of the assembly.

DUC_AT_NIGHT1.jpg

This photo was taken at twilight. I took photos at full darkness but they simply look like spots of light against a black backdrop.
Here again, the engine RPM is at idle, but as I mentioned before there is no difference between idle and redline as far as the LED brightness is concerned.

DUC_AT_NIGHT2.jpg

Twilight again...

DUC_AT_NIGHT3.jpg

This is the running light at twilight. Of the three Luxeon Rebels only one is lit. When the brake is applied two more Luxeon Rebels come on for a total of three.


Jim

[Nick]

Nice bike!

[wcorey]

How does the amount of light it provides compare to a typical modern headlight?
Permanent high beam? Does it have a projection pattern like a standard type headlight or just project out in a cone?
A picture of it from behind shining on a wall would give some idea of what it looks like from the riders perspective.

[JimF]

I would say the LED is comparable to a 25-watt incandescent. I have the LED pointed up too high, but I do most of my driving in the daytime and I would prefer being seen by cars (shining the light more toward other driver's eyes) than being concerned about lighting the road ahead of me at night.

I did put a collimator lens on the LED light as I do for taillights. It makes the intensely bright light even brighter, but in a narrower beam. I might have done without the collimator lens for the headlight given that the Hella has that integral glass optical lens, but I am not sure what I would have gained and lost. Here again, if I had an abundance of time I could have played with both configurations, but any results posted would have been merely personal observations.

I could have made the LED work as a high/low beam as there are three emitters and in dual-filament brake light usage the LED toggles between one emitter lit (running light) and three emitters lit (braking.) Doing the same thing with the LED headlight seemed useless as just one emitter lit could be less than effective at being noticed by a car and would be very useless at night to light the road.

In the end though, just like the stock 25-watt incandescent is in my opinion useless as the motorcycle quickly overruns the beam, so too does the motorcycle at moderate speed overrun the LED beam. I wouldn't want to drive on a dark country road, but it's passable on urban streets lit with streetlights.

One benefit though is the old headlight and taillight would diminish to a very low glow at stoplights and stop signs as the engine RPMs settled into an idle. The LED headlight and taillight stay bright even at idle, making me more visible when stopped at night.

I will try to get a shot of the light on a wall at night.

[narrow_monza]

Very nice! Thanks for sharing.

[narrow_monza]

Hi Jim,

Is it possible to use such approach with both of the stator coils have one end grounded at the core?

Thanks

-Adrian

[JimF]

If I understand your question correctly, then no. The Podtronics wants to see an AC supply on two wires whose opposite ends are switching polarity.

One of my coils is grounded internally by the factory and only one of the coil wires comes out of the engine.

The other coil's two wire ends come out on two wires from my engine.

Those two wires from the coil that is not internally grounded are what I use to feed the two inputs (single phase) 12-volt Podtronics and make 12-volt DC voltage. It is that voltage that I use to power the lighting. Once again keep in mind that each coil winding is roughly 20 watts, so that's your entire budget for running any 12-volt loads. Putting a 50-watt headlight on is not going to work.

It's still possible to buy 6-volt 25-watt incandescent headlights, but to my knowledge no one ever made a 12-volt 25-watt headlight so that puts you in a tough spot.

I think Podtronics makes a 6-volt single phase rectifier/regulator. I could have used that and then run a 6-volt 25-watt headlight but I would have to question why I would want to bother converting to DC when the headlight doesn't care if the power is AC or DC. One reason to convert to DC might be to run with a battery which could run the headlight at low engine RPMs, but that means there would have to be enough power being generated at operating RPMs to run the headlight plus a little more to charge the battery.

I am surprised that both your coils are internally grounded. Only two wires come out of the engine pigtail?


Jim

[narrow_monza]

I am surprised that both your coils are internally grounded. Only two wires come out of the engine pigtail?
Jim

I'm surprised too. See photos below

stator.JPG

[JimF]

I wonder if that one coil lead with the giant blob of solder on it wasn't originally attached to an outgoing wire...


Dew-Cat-tea Bob could tell us.


Mind you, eventually one end of both coils get connected to ground on an AC bike eventually, but the reason for not grounding both coils inside the engine relates to having to share the ignition circuit winding with the brake light. It's unclear to me how this bike ran/runs a headlight (25 watts typical) and a brake light (15 watts typical) along with an ignition circuit.


Jim

[narrow_monza]

I wonder if that one coil lead with the giant blob of solder on it wasn't originally attached to an outgoing wire...

I agree, it looks like it was grounded right at that solder point.

Dew-Cat-tea Bob could tell us.

That would be great.

Mind you, eventually one end of both coils get connected to ground on an AC bike eventually, but the reason for not grounding both coils inside the engine relates to having to share the ignition circuit winding with the brake light. It's unclear to me how this bike ran/runs a headlight (25 watts typical) and a brake light (15 watts typical) along with an ignition circuit.

I see your point but suppose we don't want the brake light included in the ignition circuit, couldn't I just dedicate one magneto coil to the ignition and the other to all lights and horn (with both coils sharing the chassis ground at the stator)? Would that work or am I missing something?

Thanks

-Adrian