I'm trying to upgrade my DT3's lighting system to 12V so that I can run the headlight off of the battery and have a brighter output. This solves a couple of problems that I know could be solved in other ways, namely the bulb blowing could be fixed via 6V regulator or installing a new 12V Halogen headlight. However, I'd like to have brighter LEDs in my headlight and taillight because I'm mostly riding after work: it's getting harder and harder to make it back in time before sunset.

I've been perusing the forums for some solutions about headlight LED conversions and I'm thinking the best solution so far has been presented here:
However, I'm feeling a little wary of this because of . In brief, he states that LEDs in holders/reflectors designed for halogens will lead to poor lighting patterns and brightness, and may increase blinding of other drivers, simply because of the way LEDs emit planar light, rather than from a single focal point like halogen bulbs. One question then is have people successfully and consistently driven in the dark with the type of conversion I linked above?

So this feels sacreligious 've been considering in light [ ]of the Daniel Stern article is buying a fully LED headlight, with reflectors and LEDs integrated in the bucket. The best option I've found so far have been! I think they'll look kind of silly and I'm worried about them not fitting in the holder, but I'm more worried about killing myself in the dark. So I'm wondering if anyone has ever tried this or done it successfully, and am requesting any thoughts from those wiser than me.

Best, 
Lou
 

The site isn't letting me post links, unfortunately. The forum post I was considering copying is called "Headlight conversion '72 CT 2", the Daniel Stern article is called, "Thinking of converting your halogen headlamps to HID or LED?", and the Harley-style LED Headlights are called "5.75 LED Headlight High Low Beam for Harley Sportster XL 883 1200 Dyna", or some similar thing.

You can't post pics/links until you have a dozen posts, it's to stop spammers and scammers. Hopefully someone in here can provide guidance.

Here we go.

Headlight conversion '72 CT 2 - Vintage Enduro Discussions

I'm not sure if you realize that Yamaha and other manufacturers used a "balanced" electrical system to keep the voltage in range before regulators were available.


What is the wattage of the Harley LED?  Are you planning on running a "constant loss" system where you hook up the new headlight to a 12v battery that runs dead eventually or are you relying on the engine keeping a 12v battery charged?  
 

Ah okay, that makes sense! Thanks for letting me know about the spam checkpoints. Also thanks for posting that link Leal. I'm realising now that their conversion was all 6V, and my hopes were falsely raised. 

About the 'balanced' electrical system: no, I've not heard that term before – what does it mean?

But yes, basically my plan is to hook up the stator to a new 12V battery and run all lights off of it, including the headlight. I'm hoping to find a bulb with low enough wattage that doesn't put too much strain on the battery so that it can be charged as I run the bike in high revs. I've heard of doing this with some success (I would cite my sources but still can't post links lol sorry), but am definitely aware that I might have to use the Rex's speedshop 12V coil conversion kit. 

This is maybe starting to feel like a fool's

A challenge is the system is designed to balance the output of the magneto power with the load to keep voltage in check.  

There is basically three sets of lighting/charging coils. The key switches the stator input to the rectifier depending on electrical load selected. One charges the battery in the daytime (lowest output). The second is used when the key is in "lights on" position and provides a little bit more power to the battery to keep it charged (but not overcharged) with the taillight on. 

The third coil powers the headlight with key in "lights on" position and is designed to match the wattage (power) of the headlight filament.  This wire (yellow) provides a lot more power than either of the wires that charge the battery.  

So the challenge is if you want to run a headlight off the battery, most of the power the magneto can produce (yellow wire) isn't connected to the battery through the rectifier.  

What several members used successfully years ago was to add a 12v Trail Tech AC regulator to the yellow wire and use a 12v H4 headlamp with a halogen bulb.  Yellow is AC so with an LED you might also need to add a rectifier to the yellow to "half wave" DC it.  Note that what they did was keep the battery circuit 6v and use a 12v headlight on the separate yellow wire (AC) circuit.

Here is a blurb from a Yamaha doc that says a couple words about the balanced system

Also, just FYI, a 12v headlight isn't automatically "brighter" than a 6v.  

The later monoshock models for example had MUCH better headlight output because they had good voltage regulators and Yamaha could put higher output lighting coils in the stator and not worry about the voltage going too high.  

I asked what the wattage of the LED (no answer) was because the stock stator puts out just about 35 watts max on the yellow to match the 35w headlight bulb used.  If the new LED is only 25 watts, it will be nice and bright because you have 35 watts available...  (and you'd probably want to use a voltage regulator along with a rectifier on the yellow)

If you connect up a 100 watt bulb and only have 35 watts of power, it's going to be dim as heck.  WORSE than stock.  

If it was me, I'd go with the VAPE system and you'll have PLENTY of power to run a regular 12v headlight (cheap) or almost any headlight you want.  The cost of the VAPE can't be much more than the cost of those very expensive Harley LED headlights.

Thank you for the very thorough explanation, that demystified a lot of things that have been confusing me. Sorry I didn't include the wattage of the Harley headlight; they range a lot depending on which one you're looking at, but most I've seen start at 35 W and go up to 100 W which is obviously way too much. 

One thing I started thinking about when reading through your explanation is: could I hook up the yellow wire to the battery with a voltage regulator between the coil and battery? The voltage regulator would prevent over charging of the battery, and giving the battery more power would prevent it dying from too much draw from more powerful lights.

I think VAPE is making more and more sense though, you're right. 

Keep in mind the power from the stator is "AC" and a battery is "DC".  So you'd have to "rectify" the voltage on the yellow wire before connecting it to the battery.  

One thing I've thought of trying, but never have, is using a cheap modern 12v regulator/rectifier combination on the green nighttime and yellow wires coming out of the stator and connecting the regulator output to a 12v battery.  I'm not sure if you'd have to float the grounds on the lighting coils or not.