Super Simple Controller For Motorcycle LED Lights

For automobiles, especially motorcycles, auxiliary lighting that augments the headlights can be quite useful, particularly when you need to drive/ride through foggy conditions and poorly lit or unlit roads and dirt tracks. Most primary lighting on vehicles still relies on tungsten filament lamps which have very poor efficiency. The availability of cheap, high-efficiency LED modules helps add additional lighting to the vehicle without adding a lot of burden on the electrical supply. If you want to add brightness control, you need to either buy a dimmer module, or roll your own. [PatH] from WhiskeyTangoHotel choose the latter route, and built a super simple LED controller for his KLR650 bike.

He chose a commonly available 18 W light bar module containing six 3 W LEDs. He then decided to build a microcontroller based dimmer to offer 33%, 50% and 100% intensities. And since more code wasn’t going to cost him anything extra, he added breathing and strobe modes. The hardware is as barebones as possible, consisting of an Arduino Nano, linear regulator, power MOSFET and control switch, with a few discretes thrown in. The handlebar mounted control switch is a generic motorcycle accessory that has two push buttons (horn, headlight) and a slide switch (turn indicators). One cycles through the various brightness modes on the pushbutton, while the slide switch activates the Strobe function. A status indicator LED is wired up to the Nano and installed on the handlebar control switch. It provides coded flashes to indicate the selected mode.

It’s a pity that the “breathing” effect is covered under a patent, at least for the next couple of years, so be careful if you plan to use that mode while on the road. And the Strobe mode — please don’t use it — like, Ever. It’s possible to induce a seizure which won’t be nice for everyone involved. Unless you are in a dire emergency and need to attract someone’s attention for help.

32 thoughts on “Super Simple Controller For Motorcycle LED Lights

  1. You can use any patent you like for anything you build yourself. Patents cover only commercial use. So you won’t be able to run a kickstarter or a webshop with modules with that effect. Patent clerks don’t roam the highways either, so you won’t be pulled over and shot. Funny variable vehicle lightning could be illegal for other reasons like impersonating a squad car or motorcycle.

    1. Forget impersonation, these lights are illegal for road use at all unless they have a DOT stamp, which I highly doubt those do.

      These are likely to just be another set of blindingly bright, poorly aim-able lights that are becoming all too common on today’s roads.

      1. Nope. State laws control what goes on a vehicle, not federal.

        The federal DOT lighting requirements regulate interstate commerce, what can be sold, not what an individual can put on their vehicle.

        It’s only an issue if a state makes a law requiring DOT compliant lighting. I can’t say about other states, but Florida does not. Its lighting requireme ts for vehicles are based on performance (visible from XX yards, etc. and color selection, not Federal standards.

  2. Rather than giving weird advice about patents (your laws may vary), the author should suggest reading up on laws, codes and standards designed to ensure things run smoothly (i.e. prevent ignorants from endangering (blinding) other people). Brighter isn’t necessarily better. But that already starts with adjusting your bicycle lights.

        1. So Dell must be paying Aple royalties then as my new laptop this year has a brething light. Come to think of it the last one did too.

          The world is a shitty place when crap like this is getting patented and is seen as important.

    1. a very long long time ago in a place far far away from here I added a similar effect to a debug-led on a motor controller board I made for a client. The LED was only visible during service and it could display error codes by blinking in various patterns, when all was OK, it would do the breath effect (or actually I called it a heartbeat pattern), this way the engineer could see that power was on and all was OK.
      Anyway, why the … can this kind of blinking in certain rythms be (and other nonsense) be patented, what is the world coming to?

  3. WhiskeyTangoHotel Great job. As a biker for 50 years I BELIEVE in bright lights. My problem is current draw from the charging system. Is there any way to sustain 14.8 volt @ 3000 rpm charge while running things like aftermarket lights? I’ve learned a lot about a 3phase AC stator to MOSFET voltage rectifier to DCV, but don’t understand how to balance/boost the current to compensate for the draw of extra lights. Can a VR be adjustable?

    1. The rig draws a little less than an amp at 100% (full) bright. Less, of course, in the other modes. I have a voltmeter attached to the KLR (see: and it’s has no problem staying above 14VDC and the KLR is not know for it’s superior charging system. ;) Bottom line, the rig doesn’t pull very hard on the bike’s sytem.

    2. I agree. I’ve only been riding for 15 years (since I was 15 myself) but it’s always been on old beat-up bikes from the seventies. Charging systems have come a long way since then. Most of the old bikes have aftermarket stator windings and rotors available which considerably boost their charging capability. Combine that with a decent, modern reg/rectifier and beef up the charging system’s wiring gauges, and you can run just about anything. And it’s a good excuse to get inside a crankcase and get it all renovated and sealed up again along the way.

      That said these modern LED lights sip current compared to the old bright-ass halogens. You’d be surprised, even a ’72 airhead’s tired genny will drive enough super-bright LEDs to make a mod blush.

  4. I added the same lights to my Honda Deauville. Used a pair of relays and a dimmer circuit. Relay 1 taps the rear brake light (always on) and routes the power through the dimmer then the NO of relay 2. The dimmer is on minimum brightness as a day running light. Relay 2 is wired to the high beam wire and bypasses the dimmer entirely. Hi/Lo on the stock switches!

  5. What’s the use of strobe mode on vehicle lights? I think that mode is pretty useless and irritating even on flashlights, on vehicles it can be even dangerous, especially if it’s not separated from other modes by some more complicated switch combination.

  6. There is a federal standard that allows high/low beam switching at a less than 7Hz speed for daytime use only. However I have only seen this on incandescent lights. I wonder what it looks like with LED’s, much faster response than a filament.

    I have encountered a big-ass pickup more than once (have pix) that has a long bar like this light maybe 4 to 5 times as many lights mounted on his grille in use day and night. No way. There is not yet it seems a way to have tight focus and elevation cutoff headlights that that would pass DOT standards as well as a state trouper wanting to find something wrong if they are clusters of individual LED’s. Virtually all of this aftermarket LED stuff is not DOT. Aux lights are permitted but don’t forget what auxiliary means.

    1. Yes. Most (but not all) LEDs can be brightness controlled with PWM. The exception is if the PWM is feeding a voltage regulator or similar to cut, for example; a 12VDC or even an AC power that is driving some control circuit inside an LED module.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.