LED Light causes Warning Light

[Oldrider51]

Recently purchased a 2016 R1200 RS and it has a warning light on for the license plate light being out (verified by GS-911). This replaces the 5w incandescent light that was original to the bike, previous owner at this time cannot find or threw away the original unit. Question is: can't this warning light be made to go out by adding a resistor either in parallel or series with the LED light such that the system sees the same current draw or resistance and if so how does one calculate the resistor size needed? Thanks.

[dirtrider]

Recently purchased a 2016 R1200 RS and it has a warning light on for the license plate light being out (verified by GS-911). This replaces the 5w incandescent light that was original to the bike, previous owner at this time cannot find or threw away the original unit. Question is: can't this warning light be made to go out by adding a resistor either in parallel or series with the LED light such that the system sees the same current draw or resistance and if so how does one calculate the resistor size needed? Thanks.

 

Morning 041100S

 

You will need to install the resistor in parallel (across the (+) (-) wires to increase the current draw.

 

Now on figuring the resistance? THAT is somewhat difficult as you don't know what your LED array now draws. Even figuring the (working) resistance of a 5 watt incandescent bulb is not easy as the cold resistance across the filament is different than the hot resistance.

 

A 5 watt standard license plate bulb is probably around 3-4 ohms cold & maybe just under 30 ohms using ohms law.

 

Resistors are cheap so buy a few (maybe a 10 ohm, 20 ohm, & 30 ohm --1/2 10 watt resistors). Start with the 30 ohm & if no workie try the 20 ohm, then if still no workie try the 10 ohm.

 

Careful on how & where you mount the resistor as a 10 ohm can get pretty warm in operation.

 

 

 

 

 

[Oldrider51]

Okay, dirtrider. Thanks for the info. The location is under the rear portion of the seat. Will try before I close everything up to see how warm it gets. A learning question, so why a X ohm 1/2 watt resistor, instead of a X ohm - 5 watt?

[dirtrider]

Okay, dirtrider. Thanks for the info. The location is under the rear portion of the seat. Will try before I close everything up to see how warm it gets. A learning question, so why a X ohm 1/2 watt resistor, instead of a X ohm - 5 watt?

 

Morning 041100S

 

Good question?

 

A 5 watt resistor would be larger & dissipate more heat, so yes you should probably use at least a 5 watt.

 

Actually the more I think about it you might want to go with a 10 watt+ resistor as it will better radiate the heat & the 10 watt will probably have heat dissipation fins on it.

 

 

 

[AZgman]

You need one of these: Resistor

Edited August 22, 2018 by AZgman

[Oldrider51]

Dirtrider & AZgman,

 

Had a 27 ohm resistor that I tried when connected in parallel with the Puig LED license plate light (new one with all LEDs working) and the warning light does not come on. The resistor does get pretty hot quickly. I did not know the wattage rating of the unit, the colors are Red, Violet, Black, then Gold. I read this as a 27 ohm with a 5% tolerance, but no watt rating. The resistor mentioned by AZgman seems to be more for LED turn signals, but will it work on the LED license plate light it is rated at 6 ohms, 50 watts? AZgman, have you used it with this light? Thanks again for the replies.

[dirtrider]

Dirtrider & AZgman,

 

Had a 27 ohm resistor that I tried when connected in parallel with the Puig LED license plate light (new one with all LEDs working) and the warning light does not come on. The resistor does get pretty hot quickly. I did not know the wattage rating of the unit, the colors are Red, Violet, Black, then Gold. I read this as a 27 ohm with a 5% tolerance, but no watt rating. The resistor mentioned by AZgman seems to be more for LED turn signals, but will it work on the LED license plate light it is rated at 6 ohms, 50 watts? AZgman, have you used it with this light? Thanks again for the replies.

 

Afternoon 041100S

 

A 27 ohm resistor should be pretty close (use the highest ohm that will keep the warning light off).

 

A smaller carbon type resistor WILL get pretty darn hot (reason I modified my posting above).

 

You should probably try to find a 30 watt aluminum-finned-body resistor like AZgman posted a picture to as those are better at dissipating the heat & most have mounting ears. (might need to go at to higher wattage even as high as 50 to 100 watt to find one though).

 

Just put___ 30 ohm power resistor ___ into E-Bay, pick one that is aluminum & finned (they are pretty cheap)

 

What is the diameter & length of the resistor that you used as that can probably tell us what the wattage rating it is (or close anyhow).

 

 

 

 

 

[Oldrider51]

The trial resistor is about 7.5 mm in diameter & 24.25 mm in length. It seems to get pretty hot but it may not be that bad. Will be interested to hear what you think the trial one is rated for.

 

Went to the SuperBrightLed website that AZgman referenced and talked with them about the problem. The recommended their 25 ohm x 25 watt resistor for this problem with the LED License plate light. It is a finned aluminum one. I am going to try it.

[dirtrider]

The trial resistor is about 7.5 mm in diameter & 24.25 mm in length. It seems to get pretty hot but it may not be that bad. Will be interested to hear what you think the trial one is rated for.

 

Went to the SuperBrightLed website that AZgman referenced and talked with them about the problem. The recommended their 25 ohm x 25 watt resistor for this problem with the LED License plate light. It is a finned aluminum one. I am going to try it.

 

Afternoon 041100S

 

I have some 2 watt resistors that are pretty close to your measurements, about the same dimeter but slightly shorter.

 

[Oldrider51]

Thanks, dirtrider. It probably about this wattage as it got hot pretty quickly, like in 30 seconds or less and was continuing to get hot. These were for a different light that did not operate continuously. I hope the resistor from SuperBrightLed will do the job.

[AZgman]

P = V2/R so, 144/27 = 5.34 Watts But, let's use 14v instead of 12 since the voltage does vary a bit... 196/27 = 7.26 Watts and then you should also add a safety factor, so I would suggest at least a 10 Watt rating.

Edited August 22, 2018 by AZgman

[AndyS]

041100S, What is your motive for having an LED tail light?

Edited August 22, 2018 by AndyS

[Oldrider51]

Thanks, AZgman.

 

AndyS, purchased the bike used and the LED license plate light came with the Fender eliminator kit from Puig that the previous owner installed. He knew that the warning light was on, but did nothing to correct the problem and he pitched all the original parts, NOT SMART!.