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Discussion Starter · #1 ·
Okay, so the good news: the stock relay in the USA bikes will not hyperflash if you connect the OEM euro LED turn signals in place of the incandescents.

Cool!

The bad news: the euro LEDs run at 5-9V, not 12V. If you look really carefully you can see the voltage rating on the blinker lens.

Oh to be sure: they'll light at 12V, and blink at the normal rate.

For about 30 seconds.

Then they'll stop blinking.

For good.

Here's an alternative: light eight $20 bills on fire. The amount of light output will be the same.

Soooo the LED relay and 25W resistors I bought will be returned, and I'll be going in search of a 12V -> 7V constant voltage converter (the remaining working blinkers did not light reliably at 5V on my variable power supply. 7V seemed good).

And Rugged Roads gets more of my money.

Happy to be of service here! :nerd:
 

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Discussion Starter · #2 ·
The irony is that in this comment I surmised that the LEDs might run at a different voltage. Unfortunately the service manual does not give voltage specs for the LEDs (the specs just say "LED").

I should have inspected the LED blinkers first but I got excited, damnit!
 

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That's a bummer. Does the LED relay output 7V? Maybe that's where the conversion happens?
 

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Discussion Starter · #6 · (Edited)
Does the LED relay output 7V? Maybe that's where the conversion happens?
It must, because the wiring diagram show the 13-pin relay getting power directly from the clock turn fuse and sending it directly to the blinkers.

To be clear, I don't know exactly what voltage is output since it doesn't appear to be in the specs. The blinker lens is embossed "5V-9V", but I could not get the blinkers to light at 5V on my benchtop power supply.

I have ordered some step-down ("buck") voltage regulators that can handle 800mA (the maximum for a 4W light at 5V, though I'll run higher voltage so closer to 500mA) easily. Will do a burn in test and let you know how it goes.

Still enjoying being the guinea pig...
 

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Uh, will it be helpful to check the voltage with a multimeter first before having to burn anything...$ or otherwise? Just wondering.
 

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Discussion Starter · #8 ·
Okay, so here's an update.

Item the first: DO NOT RUN THE OEM LED FLASHERS AT 9V.

They may say 5V-9V on the lens, but that's crap. They won't light at 5V, and at 9V (or indeed 8.7V) they will rapidly heat up and burn out. (If you are keeping score at home, that is 3 down, 1 to go.)

Before upping the voltage I ran a 20m burn-in test at 7V. That worked fine, with some warming but nothing alarming. Then I upped the voltage to 8.7V and fried another LED. I connected the last LED (in for a penny, in for £59.93) and tried it at 8V. It seemed to heat up fairly quickly so I shut it down, then lowered the voltage to 7.4V and tried again. After 3m at that voltage the external temp was 170ºF (ambient is 75ºF), so again I shut it down. Once the remaining blinker has cooled, I'll try it at 7.2V. I am shooting for no more than 30º above ambient.

As an aside, these little voltage regulators I am using are great. I'm feeding them 14.4V and they drop it dead accurately to whatever I set. Repeatability is within 0.01V. No significant heating, and filtering caps to avoid startup/shutdown transients. About 3.5cm x 1.5cm. Pretty good deal for $2 each!
 

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Discussion Starter · #9 · (Edited)
BTW does anyone know what voltage the incandescent running lights are fed? Obviously ~12V is the turn signal voltage but the running lights are a lower voltage so they run dimmer.

Answer: 3.5V

I figured out I could test this myself by removing the bulb, which is easy as you don't need to remove the turn signal, just the lens.

However, 3.5V is much too low to run the LED blinker (especially after the 0.6V drop in the voltage regulator), which means ... no running lights when connecting the Honda LEDs to the stock US incandescent relay. I could design a circuit that would work but it would require connection to a constant 12V source. It's probably not worth the extra effort (heck, many of you may reasonably ask why I've taken it this far).

Since I already have large LED fogs on the crash bars that I run all the time, I'm not super concerned about losing the running lights.
 

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I have to wonder what Honda's reasoning was with creating two completely different signal systems with vastly different wiring looms and control boxes.

Honda is known for interchangeability and manufacturing standards. Seems to me like someone decided to get extra fancy and they couldn't get the incandescents to work on the lower voltage/amperage.


Sorry you ended up killing those expensive lights. Maybe you can retrofit the board with 12V led's and resistors to run the US voltages.
 

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Discussion Starter · #11 ·
I have to wonder what Honda's reasoning was with creating two completely different signal systems with vastly different wiring looms and control boxes.
Yeah, I agree it is weird. But it's also true that LED and incandescent circuits are designed very differently -- as I am demonstrating with my misadventures.

So having done more research on LEDs I think I understand better what is going on. I was assuming that the expensive LED assemblies had their own drivers built in, but they obviously don't. The LEDs are expecting an external constant-current driver, which will limit the voltage once a certain current draw is reached in order to avoid thermal runaway, where the LEDs draw more and more current as they heat up. This is obviously what was happening to the signals when I fed them higher voltages.

I have concluded that at 7V the LEDs are bright enough as turn signals and will not overheat, especially given the 50% (flashing) duty cycle and limited run times. (Also, the power draw at 7V is only about 1.6W, is well below the 4W stamped on the lens, though I have learned not to trust the lens stamp.) So I will be connecting the flasher positive wire to my buck regulator set to 7V.

However, from this other post I learned the the front turn signals on US bikes actually have a third conductor, which I am almost positive is the 3.5V supply for the running lights. To this conductor I will add a boost regulator that will bring the 3.5V up to around 6V, which gives an adequate brightness for daytime running lights. I'll do another burn in test to confirm that the LEDs are still happy at this even lower voltage, but with the regulator in place I don't expect any problems. This will also let me avoid having to run a PWM generator to modulate the LED output at high frequency, the usual way of dimming an LED (and one that's necessary if you want to dim to very low levels).

Both the buck and boost regulators are very small so I should be able to heat shrink everything together into a compact package. I'll report in once the replacement lights arrive.
 

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New manual, tri color, AT owner here...


ablock, the effort is much appreciated. When get this sorted we'll all owe you. If you're ever riding through Mendocino County or the Mendocino National Forest and need any advice hit me up. Also have a cool cabin in the redwoods with a year round creek that you're welcome to stay at on your adventures. About 90 miles north of you. This goes for the rest of you reading too.
 

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If you want to try LED Indicators but dont want to zap your top quality ones whilst working out the wiring why not try some low cost LED indicators from Stafford Vehicle Components Ltd, £32 for a pair, not super good looking I agree but if you blow them no loss. Note they supply the resistors required for £16. So £48 in total.
http://www.s-v-c.co.uk/product/spear...cators--pair-/ They also have a slightly more modern type, a bit dearer. Plus they do an LED relay. I have not used these and am happy with my regular bulbs. If you explained your concerns I'm sure they could advise if their kit is suitable.

This article explains why a resistor is required too.
http://led.linear1.org/why-do-i-need...r-with-an-led/
 

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Yeah, I agree it is weird. But it's also true that LED and incandescent circuits are designed very differently -- as I am demonstrating with my misadventures.

So having done more research on LEDs I think I understand better what is going on. I was assuming that the expensive LED assemblies had their own drivers built in, but they obviously don't. The LEDs are expecting an external constant-current driver, which will limit the voltage once a certain current draw is reached in order to avoid thermal runaway, where the LEDs draw more and more current as they heat up. This is obviously what was happening to the signals when I fed them higher voltages.

I have concluded that at 7V the LEDs are bright enough as turn signals and will not overheat, especially given the 50% (flashing) duty cycle and limited run times. (Also, the power draw at 7V is only about 1.6W, is well below the 4W stamped on the lens, though I have learned not to trust the lens stamp.) So I will be connecting the flasher positive wire to my buck regulator set to 7V.

However, from this other post I learned the the front turn signals on US bikes actually have a third conductor, which I am almost positive is the 3.5V supply for the running lights. To this conductor I will add a boost regulator that will bring the 3.5V up to around 6V, which gives an adequate brightness for daytime running lights. I'll do another burn in test to confirm that the LEDs are still happy at this even lower voltage, but with the regulator in place I don't expect any problems. This will also let me avoid having to run a PWM generator to modulate the LED output at high frequency, the usual way of dimming an LED (and one that's necessary if you want to dim to very low levels).

Both the buck and boost regulators are very small so I should be able to heat shrink everything together into a compact package. I'll report in once the replacement lights arrive.

Have you confirmed the front lights are 3 wire?

If that's true and they provide the 3.5v as you suspect, why not use the 12v+ signal as the trigger to get the signals to flash using a small relay?

Assuming you use a bosch SPDT, you could pin 85/86 with the 12v signal feed and 30/87A as the NC circuit.

You could also use a MICRO version so as not to take up much room.




When the flashers execute, the relay will in turn pulse the DRL's in opposite sequence simulating a flasher.

Something to think about.

Anyways, thanks for all the work you've done. Giving me some serious ideas...
 

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Discussion Starter · #15 ·
If you want to try LED Indicators but dont want to zap your top quality ones whilst working out the wiring why not try some low cost LED indicators from Stafford Vehicle Components Ltd, £32 for a pair, not super good looking I agree but if you blow them no loss.
Because I don't know if the LEDs have the same forward voltage and max current as the OEM ones. I agree that experimenting on cheaper parts has a certain appeal... :laugh:
 

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Discussion Starter · #16 ·
Have you confirmed the front lights are 3 wire?

If that's true and they provide the 3.5v as you suspect, why not use the 12v+ signal as the trigger to get the signals to flash using a small relay?
I like that idea but it would not allow me to use a different brightness for the running lights and the flashers.

As it stands my plan is to buck (limit) the voltage on the 12V circuit and boost the voltage on the 3.5V circuit. The voltages I am using seem to be safe as far as excessive current is concerned. However, I might use a constant current buck converter on the 12V circuit for extra safety and to eke out the maximum brightness. The price is a bit higher ($8 vs $2).
 

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ablock, and others, keep up the good work! Your experimentation is much appreciated. I don't know if they are configured in the same way, have similar specs. etc, but there are lots of really cheap LED blinkers on ebay. I'm happy to Pay Pa some funds for a few sets to experiment with.
 

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Discussion Starter · #18 ·
Ha ha all you chaps thanking me for being the guinea pig, feel free to send over some Omaha Steaks, or Amazon gift cards, or a $20 bill taped to the back of a Miller Millermatic 212 Autoset MIG welder with Spoolmate 200 spool gun.
 

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Discussion Starter · #19 · (Edited)
Okay, just did a little more research with my non current-regulated power supply. I wanted to see how much current (and thus power) the LEDs pulled at various voltages. See the chart below for details.

At 6.5V the light is definitely quite visible (though I need to confirm in full daylight), so this seems like a good setting for the 3.5V boost regulator. I'm not worried about a constant current source here as the power (~1W) is way below the rated 4W.

As you can see, at around 7.2V you begin to exceed the LED's wattage rating, so it's too high for the flasher setting. Moreover, at these higher voltages you can readily see the thermal runaway on the ammeter: the current just keeps creeping up and up, +100mA every few seconds. However, around 7.0-7.1V / 0.4A gives a very bright light that is still within the safe power range and the current draw there seems pretty stable.

But this new data confirms that a constant current regulator on the buck side of the circuit is the right choice. I will likely set the CC output limit to ~500 mA.

More to come after the new regulators arrive on Friday...
 

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I like that idea but it would not allow me to use a different brightness for the running lights and the flashers.

As it stands my plan is to buck (limit) the voltage on the 12V circuit and boost the voltage on the 3.5V circuit. The voltages I am using seem to be safe as far as excessive current is concerned. However, I might use a constant current buck converter on the 12V circuit for extra safety and to eke out the maximum brightness. The price is a bit higher ($8 vs $2).
It absolutely would.

Remember, 30 can be used for the output with 86a and 87a as the inputs. Put a different voltage to each 86/87a and output to the 30 post and VIOLA!! As the relay is triggered (nc - no - nc - no - nc) your voltage changes and thus a turn signal is born.


So, if we think about it this way, you only need a voltage regulator for the 12V+ to drop this to 6.5V+ for use as the signal.

on the relay:

Trigger:
85: To + from bike signal
86: To - from bike signal (diode isolate 85/86 with N4001)

Feed:
87a: (NC) 3.5v+ from bike signal (DRL feed)
87: (NO) 6.5v+ from bike signal (regulated)
30: To + of factory LED winker
 
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