# L.E.D. Resistor Help

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• 01-09-2019, 02:52 PM
jr44
L.E.D. Resistor Help
I have 2017 R1200R

Recently installed a Puig fender eliminator kit that also has a L.E.D. license plate light replacement.
Everything works and looks great. However, the new L.E.D. light is tripping my dash warning light for bulb malfunction.

Since the L.E.D. is not canbus I believe I need a resistor to match the previous bulbs load, voltage, etc.

Does anyone have any experience and/or fixed this issue? I do not know how to determine wich resistor I need to install. Puig has been no help.

• 01-09-2019, 03:42 PM
20774
Welcome to the forum! There are a couple of threads in the Similar Threads pane at the bottom of the screen that seem to touch on the issue. Good reading while you wait for more current answers.
• 01-09-2019, 09:04 PM
gloucesterman
It's All Math
Hi,
Using Ohm's law where current (amps) = voltage divided by resistance, you only need two of the values to figure out the 3rd. Once you have all three values multiply current (amps) times volts to get watts. Again if you know two of the values you can calculate the third. Calculate your original load, using the formula's figure out how much resistance is needed to equal the original load than calculate the wattage of the resistor needed.
Later,
Norm
• 01-09-2019, 10:42 PM
Omega Man
Welcome to the forum!
I did some looking around and any cures past purchasing a whole aftermarket specific LP light ended up either not working or only working a short time.
I guess to [I]really[/I] attempt to get this to work, you would have to get a few LEDs and some lab grade resistors and make up a perfect match.
OM
• 01-11-2019, 09:08 PM
jr44
[QUOTE=gloucesterman;1152900]Hi,
Using Ohm's law where current (amps) = voltage divided by resistance, you only need two of the values to figure out the 3rd. Once you have all three values multiply current (amps) times volts to get watts. Again if you know two of the values you can calculate the third. Calculate your original load, using the formula's figure out how much resistance is needed to equal the original load than calculate the wattage of the resistor needed.
Later,
Norm[/QUOTE]

Thank you for your the info!
The original bulb and wire, I'm unable to locate and test for the above values.
Far as I can tell from the bulb itself from online, is 5watts-12 Volts.
Is this enough to go on?
• 01-11-2019, 09:51 PM
gloucesterman
Yes
Hi,
Yes, 5 watts at 12 volts using Watt's law and basic algebra will give you .42 amps draw per bulb which you can now plug into Ohm's law to get the resistance of each bulb, 5.04 ohms.
Later,
Norm
PS
Watt’s law - 5 watts = amps X 12
Algebra – amps = 5 / 12 or .42 amps per bulb
Ohm’s law .42 amp = 12/resistance
Algebra – resistance = 12 x .42 or 5.04 ohms per bulb
• 01-12-2019, 01:49 PM
azgman
Correction: R=V/I so 28.8 Ohms for the resistor. Or, P=V2/R so R=V2/P 144/5=28.8 ohms
• 01-12-2019, 02:48 PM
Omega Man
From the Department of Keeping it Simple-

[url]https://www.electricalsafetyfirst.org.uk/watts-to-amps-calculator/[/url]

OM
• 01-12-2019, 06:29 PM
gator
Close however keep in mind the resistor must be placed in Parallel. so this changes some values.
Gator
• 01-12-2019, 07:09 PM
azgman
[QUOTE=Omega Man;1153150]From the Department of Keeping it Simple-

[url]https://www.electricalsafetyfirst.org.uk/watts-to-amps-calculator/[/url]

OM[/QUOTE]

What, we can't do simple math anymore?! ;)

Now if you want to get picky, there may be a more complex impedance at play here so you would need to look at inductance and capacitance too. Then there is the fact that the voltage varies from about 12.6 to 14 as load changes on the bikes electrical system, and then of course, the phase of the moon has to be considered...
• 01-12-2019, 09:00 PM
PGlaves
[QUOTE=sharsman;1152860]I have 2017 R1200R

Recently installed a Puig fender eliminator kit that also has a L.E.D. license plate light replacement.
Everything works and looks great. However, the new L.E.D. light is tripping my dash warning light for bulb malfunction.

Since the L.E.D. is not canbus I believe I need a resistor to match the previous bulbs load, voltage, etc.

Does anyone have any experience and/or fixed this issue? I do not know how to determine wich resistor I need to install. Puig has been no help.

If Puig can't supply a light that works and is compatible with your bike I would send their junk back to them. We shouldn't need to buy stuff and then find work-arounds for their crap not working.
• 01-12-2019, 10:02 PM
gloucesterman
????
Hi,
azgman your confusing me, ohm law is I = V/R, that’s a formula, so when you move a value from one side of the equal sign to the other the function that took place on the original side is reversed, ie was multiplication, now division, was addition now subtraction???? The same with Watt's law W = I x V. So when I plug in his values to Omega Man’s link it comes up .42 amps draw per bulb. And resistance per bulb is 5.04 ohms. His resistor will be based on the difference between the stock bulb and the new LED's. Also Gator using these formula's the fact that it is being wired in parallel which is needed will not change the values??? The bike is spec'ed at 12 volts so that is what all of the electrical spec's are based on. Inductance and capacitance, yeah let's keep it simple!!!
Later,
Norm
• 01-12-2019, 10:35 PM
azgman
[QUOTE=gloucesterman;1153199]Hi,
azgman your confusing me, ohm law is I = V/R, that’s a formula, so when you move a value from one side of the equal sign to the other the function that took place on the original side is reversed, ie was multiplication, now division, was addition now subtraction???? The same with Watt's law W = I x V. So when I plug in his values to Omega Man’s link it comes up .42 amps draw per bulb. And resistance per bulb is 5.04 ohms. His resistor will be based on the difference between the stock bulb and the new LED's. Also Gator using these formula's the fact that it is being wired in parallel which is needed will not change the values??? The bike is spec'ed at 12 volts so that is what all of the electrical spec's are based on. Inductance and capacitance, yeah let's keep it simple!!!
Later,
Norm[/QUOTE]

I = V/R, to find R, multiply both side by R this gives I * R = V * R / R. R/R = 1 so I * R = V. Next divide both sides by I, so I/I = 1 and gives R = V/I. To prove this, take the equation I = V/R If V=12 and R=5.04 Ohms then I = 12/5.04 = 2.38 Amps, not .42 Amps. 12/28.8 = .416 Amps
• 01-12-2019, 10:45 PM
rick601
[QUOTE=PGlaves;1153193]If Puig can't supply a light that works and is compatible with your bike I would send their junk back to them. We shouldn't need to buy stuff and then find work-arounds for their crap not working.[/QUOTE]

^^^this^^^
Unless, of course, the description (not the fine print) indicated something else was needed...AND they told you what it was. I'm becoming a "find a good dealer and build a good relationship with them" kinda guy; to the point where they might even advise me on aftermarket ideas that they may not sell (in exchange for your ((my)) willingness to pay the briksandmortar premium.