Wiring DC headlight? Do I need a regulator?

[XR200oldguy]

I plan on wiring my DC led headlight using a bridge rectifier to convert AC to DC using VegasRomaniacs instructions. Do I need a regulator if I’m using the rectifier? Where would the best place be to wire the switch in? Here’s his schematic:

[Chuck.]

I recommend using a regulator/rectifier, and I don't think you need the diode since the rect uses diodes. The motorcycle electrical system has a lot of electrical noise because of the ignition and the cap acts as a filter to help the reg to work better.  A 10,000ufd 50volt  cap is all you need.

Any Honda rect/reg will work, or an aftermarket unit.  You didn't say what year XR200, early ones used an internally grounded stator (blue wire out) and later ones have a floating ground (pink and yellow wires out). Some of the XRs use a 4 wire AC regulator that look like a DC rectifier. 

[Red NT]

https://www.cyclopsadventuresports.com/Rectifier-for-LED-Light-Module_p_85.html

[XR200oldguy]

I have a 50amp bridge rectifier from eBay and a 50v 10,000 cap. I have the later model stator. I think I’ll be good if that’s all I need. I need to make sure the connections are water proof. I ride in mud and all weather. So I just need to round one stator wire and run the other to the rectifier?

[Chuck.]

The late stator has pink and yellow wires that you connect to the AC inputs of the rectifier. Their connections in the Honda wiring harness is a short jumper that shorts the stator windings.

[XR200oldguy]

I got it all installed and ran for about 20 minutes with the light on then the capacitor blew out! It was wired per the diagram so any thoughts as to what happened? Do I really need that capacitor?

[Chuck.]

Did the rect provide regulation? Was it a chinese cap?

[XR200oldguy]

The cap was made by topcon which is Chinese. I removed the cap and the light still ran fine but I will see if the rectifier is actually putting out DC current when I get home tonight

[MCRIPPPer]

you need a regulator. i have seen motorcycle stators put out 70vAC and high rpm without a regulator. if you put a rectifier on you will get dc but it still might get up to 50-60vdc and blow out your electrical. get a reg/rec assembly or get an ac regulator and use your rectifier if you want. if you just want to run a headlight you don't need a rectifier, but then you cant use a capacitor. you also want to use a "full bridge rectifier". just using a diode will cause more flicker than just running it on AC. 

Edited July 6, 2018 by MCRIPPPer

[XR200oldguy]

Ahh, that makes sense. I’ll get the all in one regulator/rectifier. Thanks for the help!

[chadzu]

You will still need a cap or a battery to keep everything happy.

[XR200oldguy]

I thought the cap was just to stop any flickering?

[MCRIPPPer]

the usual reason for a battery is to be street legal and so the lights don't dim as much when the brake light or turn signals come on. a motorcycle works totally different form a car, where you really need the battery to stabilize the alternator output. 

[Chuck.]

The cap stops more than flickering. The ignition system shares ground with the light system and creates a lot of electrical noise that causes the regulator to over react.  Using a good battery, or a capacitor, on the DC side filters out the noise so the regulator can function properly. The symptom of poor regulation is the headlight dimming as engine speed increases.