Any EEs Here? School me on Relays?

[xsephirot]

Led's are funny little devices. Each single led has 2 major parameters, forward voltage and max forward current.The forward voltage is fixed and cannot be changed, the current on the other hand can be varied up to the max permissible and thats how the brigthness is controlled. If you have a 10watt led that runs on 10volts we can quickly calculate that in order to emit 10watts of power(most of it being light) we need 1 amp of current. power=voltage*current. therefore you need to limit the current with a resistor to 1 amp or your little led will fry.now if your led drops 10volts and your battery is lets say 12 volts you have 2 volts left over that will be dropped across the resistor you are using to limit the current.(this is a series circuit) To select the proper size resistor you use the formula voltage(volts)=current(amps)*resistance(ohms). to solve for resistance divide 2 volts  by 1 amp= 2ohms. You also need to calculate the power rating of your resistor ( or it too will fry), power = voltage*current, p=2*1= 2watts. resistor needed= 2 ohms 2 watts.
If your led light bulb that you want to install is rated for 12volt use, it shouldn't work when you try to dim it by cutting its voltage by any means.

One way to make an led emit more light than its rated is to send a large current through it but for a very small amount of time. If our previous led has a max current rating of 1 amp (thats continuous) and we decide to send 5 amps through it but for a very short period of time we can get 5 times the power. the problem is that you will only get a quick flash of light. yes you guessed it, why don't we do that alot and really fast. if you pulse that led faster than 30 times per second it will appear as a continuous light source to the human eye. That is how those intelligent controllers work.

in order to decide what size wire to use you need to know how much current it will carry. for a 14 guage wire you can run about 20 amps through a 15 foot length.
 

scara, thank you for that quick 101! That helped me quite a bit. These are the LED's I'm hoping to run on my bike: http://www.visionxusa.com/LED-Optimus_Series/c1_247/index.html

It is plug and play if I choose to use their harness and it's handlebar mount. I am hoping to use my own handlebar mount which is why I'm all confused. Apparently it has a built in dimmer board with a special wire that needs to be connected to a dimmer relay.

I was told I could hook up the relay power source to my factory h4. Therefore when I switch the ignition to on, the dimmer relay would be powered on and draw 50% power. When I flip the lights to high beam the dimmer would be off and draw should be 100% but since the h4 would also be off then I would lose the forward voltage? (if i learned this right). The question is where would I connect the constant power source in relation to the dimmer relay?

Am I talking in circles or did I lose myself and everyone?

[Bill in OKC]

There is a PDF wiring diagram at the bottom of the page.  It looks reasonable to me.  Pretty much every manufacturer will have recommendations on how to use their device.  Tech notes etc.  I would look into getting more info on how the prime drive unit works - it could just be a high/low or on/off thing to change the light from high to low and that would make it easy..

[scaramanga]

the relay shown in the wiring diagram only applies power to the unit and light is on at max. lets call this the power relay.
it looks like you'll have to buy this option also
http://www.visionxusa.com/Accessories-Dimmer/c14_215/index.html
this unit we will call the dimmer relay/unit. you should send them a note for more info on this unit so you could possibly use your own switch instead of theirs.

[xsephirot]

There is a PDF wiring diagram at the bottom of the page.  It looks reasonable to me.  Pretty much every manufacturer will have recommendations on how to use their device.  Tech notes etc.  I would look into getting more info on how the prime drive unit works - it could just be a high/low or on/off thing to change the light from high to low and that would make it easy..

Yeah I saw that, but it doesn't show how the wiring works with the relay dimmer

the relay shown in the wiring diagram only applies power to the unit and light is on at max. lets call this the power relay.
it looks like you'll have to buy this option also
http://www.visionxusa.com/Accessories-Dimmer/c14_215/index.html
this unit we will call the dimmer relay/unit. you should send them a note for more info on this unit so you could possibly use your own switch instead of theirs.

I was thinking of using this switch instead http://www.lights.skenedesign.com/IQ_175.shtml.

However the dealer for the manufacturer says it would not work. I'm not sure why. I've been tossing and turning thinking of this in bed all of last night.

[tuxicle]

I was thinking of using this switch instead http://www.lights.skenedesign.com/IQ_175.shtml.

However the dealer for the manufacturer says it would not work. I'm not sure why. I've been tossing and turning thinking of this in bed all of last night.

The IQ-175 looks like it's designed for incandescent headlamps. It will do Pulse width modulation (that was referenced in scaramanga's post above. The LED lights you're planning to use will likely have an LED driver circuit embedded inside. This is how it can run properly from such a wide range of voltages (spec sheet says 11-32V). This driver circuit will not "play nice" with the PWM signal that the IQ-175 puts out.

Your best bet would be to get the dimmer accessory from visionx and either get more info from them on how to use your own switch, or tear it apart and use its guts hooked up to the lo/hi beam switch on the duc.

A side note: those visionx lights are rated for "off road use," so I wonder how it'll fare on the streets. You may end up blinding oncoming traffic.

Yep, I'm an EE

[tuxicle]

One more thing: since these LED lights will draw less power than the standard halogens (especially when dimmed) you may want to consider upgrading the duc's regulator. The stock ones on the older ducs are notorious for overheating even under normal conditions, this would be accelerated with a lighter load from the electrical system.

[xsephirot]

The IQ-175 looks like it's designed for incandescent headlamps. It will do Pulse width modulation (that was referenced in scaramanga's post above. The LED lights you're planning to use will likely have an LED driver circuit embedded inside. This is how it can run properly from such a wide range of voltages (spec sheet says 11-32V). This driver circuit will not "play nice" with the PWM signal that the IQ-175 puts out.

Your best bet would be to get the dimmer accessory from visionx and either get more info from them on how to use your own switch, or tear it apart and use its guts hooked up to the lo/hi beam switch on the duc.

A side note: those visionx lights are rated for "off road use," so I wonder how it'll fare on the streets. You may end up blinding oncoming traffic.

Yep, I'm an EE

Thanks for that explanation Jim! Yeah I want the dimmer option so I can use it on the road haha.

One more thing: since these LED lights will draw less power than the standard halogens (especially when dimmed) you may want to consider upgrading the duc's regulator. The stock ones on the older ducs are notorious for overheating even under normal conditions, this would be accelerated with a lighter load from the electrical system.

Yup, already upgraded mine's to a MOSFET regulator last year... ironically after I got stranded on an interstate when the old one overheated.

[Bill in OKC]

Yeah I saw that, but it doesn't show how the wiring works with the relay dimmer

There is not any relay dimmer.  Just a relay to supply power to the headlight.  The headlight will come on when you turn the key on - you probably will not have the on/off switch shown in the schematic.  The additional prime drive box will dim the headlight and it is plug and play.  It looks kind of large and clunky so you might have to extend some cables to hide it somewhere.  The dimmer control is on that additional box so if you want to use the factory high/low switch you will need to do some wiring surgery to replace the standard dimmer switch with your stock handlebar switch.

I was thinking of using this switch instead http://www.lights.skenedesign.com/IQ_175.shtml.

However the dealer for the manufacturer says it would not work. I'm not sure why. I've been tossing and turning thinking of this in bed all of last night.

Yes that does look like it is for a standard bulb instead of an LED.  The standard bulb would be dimmed by varying the voltage applied while the LED is dimmed by varying the duty cycle (on/off time) ie PWM.

The hardest part if you go this route will be extending the cable to the dimmer box so you can hide it and splicing your high/low beam switch in to replace the switch on the dimmer box.

[scaramanga]

One more thing: since these LED lights will draw less power than the standard halogens (especially when dimmed) you may want to consider upgrading the duc's regulator. The stock ones on the older ducs are notorious for overheating even under normal conditions, this would be accelerated with a lighter load from the electrical system.

Sorry but i don't understand this. if your load is lighter (no pun intended, get it headlight....lighter  ) how would the regulator work harder.
Lighter load = less current the regulator needs to supply hence it will be happier.

[Bill in OKC]

I guess the power being generated has to go somewhere.

Another thing since you *probably* do not have the headlight on/off switch -and- the LED drawing less power you probably do not need the power relay in the schematic either.  But I would never advise doing something different than the manufacturer suggests...

[Speeddog]

Sorry but i don't understand this. if your load is lighter (no pun intended, get it headlight....lighter  ) how would the regulator work harder.
Lighter load = less current the regulator needs to supply hence it will be happier.

Seems counter-intuitive, but what tuxicle said is correct.

One of the jobs of the regulator-rectifier is to dispose of excess electrical power as heat.
Because the alternator is running 'full throttle' at all times, the R-R is dumping a lot of power even when rpm is only moderately high.
Higher power draw headlight eases the load on the R-R.

[Howie]

Sorry but i don't understand this. if your load is lighter (no pun intended, get it headlight....lighter  ) how would the regulator work harder.
Lighter load = less current the regulator needs to supply hence it will be happier.

If the alternator was is like the type used in cars or some touring motorcycles (field winding rather than a permanent magnet rotor) where the regulator controls output by field current) you would be correct.  In the case of our Ducatis and most motorcycles tuxicle and Speeddog are correct, excess current turns to heat.  Too much heat makes smoke, and we all remember what happens when the smoke gets out:

ELECTRICAL THEORY BY JOSEPH LUCAS

Positive ground depends on proper circuit functioning, which is the
transmission of negative ions by retention of the visible spectral
manifestation known as "smoke".

Smoke is the thing that makes electrical circuits work. We know this to be
true because every time one lets the smoke out of an electrical circuit, it
stops working. This can be verified repeatedly through empirical testing.

For example, if one places a copper bar across the terminals of a battery,
prodigious quantities of smoke are liberated and the battery shortly ceases
to function. In addition, if one observes smoke escaping from an electrical
component such as a Lucas voltage regulator, it will also be observed that
the component no longer functions. The logic is elementary and inescapable!

The function of the wiring harness is to conduct the smoke from one device
to another. When the wiring springs a leak and lets all the smoke out of the
system, nothing works afterward.

Starter motors were considered unsuitable for British motorcycles for some
time largely because they consumed large quantities of smoke, requiring very unsightly large wires.

It has been reported that Lucas electrical components are possibly more
prone to electrical leakage than their Bosch, Japanese or American
counterparts. Experts point out that this is because Lucas is British, and
all things British leak. British engines leak oil, British shock absorbers,
hydraulic forks and disk brake systems leak fluid, British tires leak air
and British Intelligence leaks national defense secrets.

Therefore, it follows that British electrical systems must leak smoke. Once
again, the logic is clear and inescapable.

In conclusion, the basic concept of transmission of electrical energy in the
form of smoke provides a logical explanation of the mysteries of electrical
components - especially British units manufactured by Joseph Lucas, Ltd.

[ducpainter]

If the alternator was is like the type used in cars or some touring motorcycles (field winding rather than a permanent magnet rotor) where the regulator controls output by field current) you would be correct.  In the case of our Ducatis and most motorcycles tuxicle and Speeddog are correct, excess current turns to heat.  Too much heat makes smoke, and we all remember what happens when the smoke gets out:

ELECTRICAL THEORY BY JOSEPH LUCAS

Positive ground depends on proper circuit functioning, which is the
transmission of negative ions by retention of the visible spectral
manifestation known as "smoke".

Smoke is the thing that makes electrical circuits work. We know this to be
true because every time one lets the smoke out of an electrical circuit, it
stops working. This can be verified repeatedly through empirical testing.

For example, if one places a copper bar across the terminals of a battery,
prodigious quantities of smoke are liberated and the battery shortly ceases
to function. In addition, if one observes smoke escaping from an electrical
component such as a Lucas voltage regulator, it will also be observed that
the component no longer functions. The logic is elementary and inescapable!

The function of the wiring harness is to conduct the smoke from one device
to another. When the wiring springs a leak and lets all the smoke out of the
system, nothing works afterward.

Starter motors were considered unsuitable for British motorcycles for some
time largely because they consumed large quantities of smoke, requiring very unsightly large wires.

It has been reported that Lucas electrical components are possibly more
prone to electrical leakage than their Bosch, Japanese or American
counterparts. Experts point out that this is because Lucas is British, and
all things British leak. British engines leak oil, British shock absorbers,
hydraulic forks and disk brake systems leak fluid, British tires leak air
and British Intelligence leaks national defense secrets.

Therefore, it follows that British electrical systems must leak smoke. Once
again, the logic is clear and inescapable.

In conclusion, the basic concept of transmission of electrical energy in the
form of smoke provides a logical explanation of the mysteries of electrical
components - especially British units manufactured by Joseph Lucas, Ltd.

Classic...

[scaramanga]

so ducati =


not ducati=

[xsephirot]

Slightly off topic but does anyone know how our monster's H4 works?

When we flip from low beam to high beam, does the the low beam power get shut off? Be alot easier if I could wire the dimmer relay power to the h4 low beam and the switch power directly to the high beam h4 instead of having to find a constant power source like the rear plate lights.