Electrical question re: LEDs

[willie]

I was planning on replacing the signals on my bike with 12 volt LED units. I unplugged the signal and plugged in the LED wires. I was surprised and disappointed that it won't flash. Can anyone explain why and what I have to do to make it work? I figure that the reduced current draw is the culprit. The LED unit draw is minimal. IF thats the reason will adding a resistor do the trick?
Thanks again.
Willie in TN

[TheCafeKid]

On alot of the LED signals you have to install a load balancer. Or someone was telling me about a flasher unit that doesnt look for load to flash. Dunno wich part is cheaper..

[davewallen]

For a resistor to work you would need it to be parallel to the LED, and it would need to be a pretty low value. I'm guessing a normal signal at 12 watts, which would be one amp at 12 V, which would be (oddly enough) a 12 ohm resistor. (of course, it's been 30 years since I did any electrical work) By the way, it would also need to be a 12 watt resistor - not your normal 1/8 watt types.

You would probably be better off using a flashing LED, though.

[drhach]

You don't necessarily need a load bablancer. Try using a solid-state flasher. Normally they are mechanical. Specifically, they rely on the heat created from the current to collapse a metal bar in the flasher unit. When the bar collapses from the heat, it touches a contact and closes the circuit. When it cools enough, it springs open and in turn opens the circuit back up. I may have the theory reversed but basically that is what normally happens. LEDs don't allow enough current to travel through the system to create the necessary heat. A solid state flasher just has a timed switch that opens and closes the circuit. Nothing mechanical. It should drive everything just fine.

[willie]

Thanks! I did a Google search for LED load balancers after reading the Kid's post and uncovered a post on another board that had exactly the info I needed including a schematic. Looks like a 10-12 ohm 10-12 watt resistor will do the trick and for not much $$ at all. Next step is to figure out how I can make several LED units flash sequentially. I've looked into available kits that might do the trick in that dept. Should be cool if I can make it all happen the way I hope.

[Steve]

Is your intent to add some cool-looking lights, or are you trying to reduce your electrical useage?

If you are trying to spare some electrons, adding a load resistor is going to put you right back where you were, as far as current consumption, so there is no gain.

If you don't mind spending about $10-15, just go to Auto Zone or whatever you have handy, and get an electronic flasher. As drhach mentioned, they have a timer inside, so they flash at the same rate, regardless of the load.

As far as the sequencing...you will need to do some electronics work there. There will be cascading timers involved, which are very possible, but making them small is the trick.


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[Redman]

If your intent in going to the LED lights is to reduced current draw, then adding the load balancer or the resistor will defeat that purpose by just drawing more current somewhere else.

Oh, Hi Willie.

[willie]

Understood, good buddy. My only intent was to modernize the appearance of the bags. Just trying to be a little different.
Willie in TN

[davewallen]

Thanks! I did a Google search for LED load balancers after reading the Kid's post and uncovered a post on another board that had exactly the info I needed including a schematic. Looks like a 10-12 ohm 10-12 watt resistor will do the trick and for not much $$ at all.

D^mn, I was right! (look of shock, as I pat self on back)

Can you give a link to that other site, in case this comes up again?

[willie]

http://www.jockeyjournal.com/forum/showthread.php?t=26078&highlight=LEDs

You'll see why I was so impressed.
Willie in TN

[bakalorz]

Is your intent to add some cool-looking lights, or are you trying to reduce your electrical useage?

If you are trying to spare some electrons, adding a load resistor is going to put you right back where you were, as far as current consumption, so there is no gain.

If you don't mind spending about $10-15, just go to Auto Zone or whatever you have handy, and get an electronic flasher. As drhach mentioned, they have a timer inside, so they flash at the same rate, regardless of the load.

As far as the sequencing...you will need to do some electronics work there. There will be cascading timers involved, which are very possible, but making them small is the trick.

What he said ... but timers etc is the old primitive way.
The right way to do it now is with a microprocessor.

ANY (and I litterally mean any) flash pattern or sequence you want, as many leds as you want doing whatever you want them to. And in a lot of ways actually easier than discrete timers and such.
Also much easier to make changes and adjust after its built.

And physically small if you want it to be.
The processor that controls it all is one chip, and pretty much the only other components you need is a mosfet and resistor for each output/led.

As far as LEDs go, I got some of the replacement 1156/7 bulbs, and none of them were really bright enough. What is good are the LED assemblys they make for trucks.
Like these http://cgi.ebay.com/ebaymotors/PIRAN...spagenameZWDVW

Those are pharking bright ...

I am going to replace all my tail and turn lights with LEDs, and earlier tonight was playing around with them, seeing what they looked like if you strobed them.

[Steve]

What he said ... but timers etc is the old primitive way.
The right way to do it now is with a microprocessor.

Yeah, you and I know that the microprocessor is just a fancy, updated timer (in this application), but I was just trying to keep it in easy-to-understand terms. 8-[

If you get down to it, the standard bi-metallic strip in a standard flasher is a type of timer, too, but has a duty cycle based on load. The microprocessor-controlled units are based on time, not load.

There is still an advantage to the bi-metallic flasher, though. When a turn signal is not working, you will know it, because they will not flash on that side. With an electronic unit, your indicator on the gauge panel will still flash, even if both signals (front and rear) are burned out.

All the more reason to do your T-CLOCK inspection before every ride. :shock:


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[Planecrazy]

There is still an advantage to the bi-metallic flasher, though. When a turn signal is not working, you will know it, because they will not flash on that side. With an electronic unit, your indicator on the gauge panel will still flash, even if both signals (front and rear) are burned out.

...Of course the flipside to this is that if you convert to LED's than the likelihood of a "bulb" failure is rather remote. After all, most modern LED's have a service life of 11 YEARS or so left on continuously! That's pretty darn reliable when you think about it.

Still, I agree with you that one should always do the "walkaround" before taking off into the wild blue yonder!

Regards,

[Steve]

... if you convert to LED's than the likelihood of a "bulb" failure is rather remote.

True enough, but "bulb" failure is not the only reason signals don't work. Evidently you have been lucky enough to not ever had any corroded connections. :shock:

Nah, I know better than that. 8-[


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[Planecrazy]

True enough, but "bulb" failure is not the only reason signals don't work. Evidently you have been lucky enough to not ever had any corroded connections. :shock:

Nah, I know better than that. 8-[


.

Hah!!! ... Yes, you do! ;-)

I've been pretty lucky overall, though ("knock on fake wood" - as he taps his own skull)!

Regards,