Putting two drop in CREE's in a Scooter

[jasonck08]

Ok, to start off, I have a Yamaha 125cc Scooter. The headlights are 35W's each at full power aka with the bights flipped on. Normally the lights are quite dim and run directly of the alternator. I tried switching to some better lights a while back, but they didn't make it any brighter. When you accelerate on the scooter the lights are a little brighter than when its idling, and the regular lights will not work unless the engine is on. You can use the bights when the engine is off, because it goes directly to the battery.

So now that I got that out of the way... it's time for my question. I was thinking about connecting two 3W Cree LED's with regulated boards that accept (3x18v). If for example when my scooter idles the lights take 6v's each if I installed the cree would the brightness be the same as when I idle and accelerate assuming the voltage changes to 12v's. Would the regulator board be able to handle this rapid increase and decrease in voltage. I own a DX VB-16 light and it is probably brighter or just as bright as both headlights with the bights flipped on. That's 3W's vs 70W's!

So what would happen if I were to put in two drop in modules in my scooter? Ones from DX for example. Would it work? Would I have to do anything other than making the lights fit the reflector and wiring them up?

Thanks,

-Jason

 

[Flummo]

I have a similar project now, A Derbi Senda 50cc (moped) with a single 12V 45/40W BA20D headlight. Dim at idle but lights up good at "driving rpm".

Original lamp was 35/35W - horrible! Okay, not bad for a moped, but not good enough dark nights either. Quickly replaced with a 45/40W, got a small improvement.

Started measuring voltage drop in the wiring, and found out that 1,2V disappeared between the alternator and the lamp. Not really a suprise with tiny 0,5mm2 wires and the current going through the ignition switch, the handlebar light switches, and a large number of ridiculusly small connectors.
I put a new thicker wire straight from the alternator to a relay and then to the lamp, and there was a pretty big diffrence in light output.

That is where I am today. I just ordered three Seoul P4 cold white, a 700mA driver, some diffrent optics and stuff that I intend to make a small auxillary light out of. It will be powered from the battery.
Assuming that the 45W bulb gives about 600lm and that at best 50% of that ends up on the road, I think 3*150lm from the leds will make a pretty big diffrence.

 

[jasonck08]

My single SSC emitter think its like 3 watts in my DX VB-16 flashlight is brighter than both my 35W's on high. Thats just sad. I hate the yellowish light, I want a bright white light. With the brights off I can hardly see the road light up at all. It's really sad.

So Flummo are you connecting the P4's directly to the battery with the 700mA driver?

Does anyone else care to chime in that knows anything about mods like this. I know very little. Please advise.

 

[Flummo]

That is the plan, yes, if it works good remains to be seen. So far it is a experiment, needs some testing before I even can decide if it is worth building something out of it.

I REALLY think you should check what voltage your lamps get, and what comes out of your alternator. Sounds like your lamps get a couple of volts less than they should, and that kills alot of light. Don't get me wrong, extra light from "auxillary leds" or something like that is a good idea - but I prefer to make sure that the original parts really work as they are supposed to first.

 

[Everett]

I think you would get some voltage spikes that would exceed 18V, and probably much more rapid fluctuations than the driver would like. It would probably work, but you could make it easier on the driver and LED by adding in decently large smoothing capacitors right next to the drivers.

 

[jasonck08]

My multimeter battery is dead right now, but I'll get a new one and go test what kind of voltage the alternator is giving the headlights at idle, when reving the engine, and with the bights flipped on.

Now with these CREE regulator boards, does it make it so the light is putting out the same lumens @ 5v for example and at 15v? Most regulator boards on DX are good from 3v-15v some to 18v. But for added perfection I might do as you said Everett add some sort of smoothing capacitor, although I have no clue what size / type to get. I do know stores that sell every capacitor / resistor imaginable.

I would kind of be surprised if there would be any voltage spikes north of 13V's. As when riding at a good sped (50mph for example) the regular headlights running directly off the alternator are 1/2 as bright as when I flip on the bights (with the bights the lights run directly off the battery, and the battery doesn't get above 13v) My guess would be at idle it would be around 3-6v and when riding the alternator would be giving 6-9v. Because the lights are dimmer than with the bights @ 13v I know the alternator is putting out far less than that...

 

[Flummo]

Headlights, lights, bights... You are making an excellent attempt at making me confused! :thinking: Could we please get some clarification about what's what and how everything gets driven?

At the battery, with a good battery and everything working as it should, you probably have a voltage ripple somewhere around 1-2V. But, having great experience with Murphys law, I never design things so they only work if everything else is in perfect working order!
The AC part of the system is regulated in a PWM like fashion, if the alternator gives 24V under some circumstances and you want 12V the regulator will let 24V be on for 50% of the time, and then it will shortcircuit the alternator to 0V the rest of the time.

That is absolutely fine for lightbulbs, electronics is another story unfortuneately. If the battery gets disconnected (blown fuse, broken wires...) the battery part of the electric system will see the same voltage variations as the AC part of the system. Peaks at maybe 30-50V would be normal.

I will use a driver that can take 40V, and I will connect a capacitor to smooth out the variations a bit. Not foolproof, but unless the headlight breaks or is turned off the generator is too weak to produce any dangerous voltages.

 

[jasonck08]

I'm sure that the lights are connected through something that regulates the volteage. But it is clear to me that they are not getting anywhere near 12v's. I'll take my multimeter and test tomorrow and find out for sure. These peeks of 30-50V on my little Yamaha 125cc scooter seem impossible.

 

[jasonck08]

I tested my scooters alternator. At idle the headlights get 3.8-4V when I'm driving or reving up the engine it doesn't go past 6.1 or 6.2V's.

I could just use a couple of These Cree 3v-18v drop in's

What would you recommend? Also the lights had three wires attached a positive, negative and a green wire that I'm not sure what it is for.

 

[Flummo]

I suggest repairing whatever isn't working first! You are loosing alot of voltage somewhere, and that is, worst case scenario, a very real fire hazard! Something is wrong on your bike, an adding (probably illegal?) auxillary lights isn't the solution for that. That may be the way to go when the original stuff is working at it's best and still isn't quite up for the job...

Good to know: Many digital multimeters don't give a accurate reading for AC voltage on bikes, as the way the regulator works "confuses" them. But based on my experience, it should not be more than about 2V away from the real voltage in a 12V system, and your reading is way off for just being that. TRMS digital multimeters and analogue meters is not affected and should always give accurate readings.

Did you measure what voltage comes out of the alternator (usually the yellow wire), and what you have at the regulator (probably yellow here too, depending on how the system is made and supposed do work)? Did you measure voltage drop between the lamps negative connection and ground? If not, start out with those things, and I think we can give you some help about what the problem is. Schematics for the wiring would be great help too!

A picture of the lamps/wires might give a clue what the third wire is for.


About the Cree drop in I would be concerned about the beam pattern. From the look of it, I dont think it will throw very far. For my project I ordered some diffrent optics around 10-25 degrees to see what I like the best.

 

[jasonck08]

Just to let you know, I'm in Taiwan. There are several people with the same scooter, and the headlights are also very dim. Plenty of people here have very bright aftermarket headlights. So I don't think its really illegal. I'll post a pic later, but I don't think there is anything wrong with my scooter.

 

[Meduza]

dahhh... just remove the original headlights and replace it with 7pcs of those modules for a good light ^_^