Same here.
LED resistor question
Melting Slicks
Joined: Oct 1999
Posts: 2,181
Likes: 421
From: Ponte Vedra Beach FL
And yeah, where is RC4G with his scientific analysis of the situation? I'd kinda like to know the the reason my ballasts get hot is because I have it wired wrong!
But my LED DRLs sure do look good and work good so far! 
Team Owner
Joined: Dec 2002
Posts: 32,074
Likes: 296
From: San Francisco CA
Yeah, they get hot, but so does your exhaust pipes and cat converter. Point is, precautions have been taken regarding those items, and some simple precautions should be taken with the DRL ballasts. As for how hot they get, they're too hot to touch, but I kinda doubt they would melt nosecone-area plastics or set fire to anything. But doubleback tape sure won't work, and it's better to be safe by acknowledging that they get "surprisingly hot". Thus, I chose to suspend them from a bit of wire and be done with it.
And yeah, where is RC4G with his scientific analysis of the situation? I'd kinda like to know the the reason my ballasts get hot is because I have it wired wrong! But my LED DRLs sure do look good and work good so far!
And yeah, where is RC4G with his scientific analysis of the situation? I'd kinda like to know the the reason my ballasts get hot is because I have it wired wrong!
But my LED DRLs sure do look good and work good so far! 
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
Nope, still here and nothing fried.
Did the detailed testing and documentation but had a bulb quality control issue with the all-white DRL's which required sending them back to Neal who responded that about 5% of the all-white DRL's are returned for the same issue and although he has been working with the manufacturer to resolve he does not an explanation why the bulbs fail. He has indicated that the switchbacks do not exhibit this same issue (possibly as they were designed for DRL use starting out and might utilize different internal resistors) but my goal was to eliminate the yellow running light so using switchbacks is not an option for me.
Unlike some folks here I have no problem admitting when I'm mistaken. My goal was to rely/validate my own personal results, plain and simple, and them share them accordingly. Just didn't think there was much point in posting results prior to getting a final completed configuration.
Did the detailed testing and documentation but had a bulb quality control issue with the all-white DRL's which required sending them back to Neal who responded that about 5% of the all-white DRL's are returned for the same issue and although he has been working with the manufacturer to resolve he does not an explanation why the bulbs fail. He has indicated that the switchbacks do not exhibit this same issue (possibly as they were designed for DRL use starting out and might utilize different internal resistors) but my goal was to eliminate the yellow running light so using switchbacks is not an option for me.
Unlike some folks here I have no problem admitting when I'm mistaken. My goal was to rely/validate my own personal results, plain and simple, and them share them accordingly. Just didn't think there was much point in posting results prior to getting a final completed configuration.
Last edited by RC4G; Feb 4, 2013 at 03:23 PM.
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Melting Slicks
Joined: Apr 2009
Posts: 2,431
Likes: 77
From: Lake Charles Louisiana
Ok so my plan is to install the resistors on the frame like the op posted pics of. But I will add a small but on both my self tapping screws under the resistor. So the resistor will be mounted but only contact point will be the two screws.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
Update:
OK, I believe I've come up with a solution to only send power to the 6ohm resistors when the turn signals are active (not during DRL) and have sourced the required parts.
I will be building a mock-up off the car to test the relays this weekend (hopefully) and will post the solution when I have it fully tested.
Basically the solution is a custom relay upstream of the resistors that closes the circuit based on a programmable delay. This will allows the 6 ohm resistors to provide load during the turn signal flash duration but will open the circuit (no longer feed power to the resistor) when the TS/DRL circuit stays on continuously for more than 1 second.
First generation will require a relay for each resistor but my source is working on a programmable delay relay with two independant triggers and output circuits.
I will be building a mock-up off the car to test the relays this weekend (hopefully) and will post the solution when I have it fully tested.
Basically the solution is a custom relay upstream of the resistors that closes the circuit based on a programmable delay. This will allows the 6 ohm resistors to provide load during the turn signal flash duration but will open the circuit (no longer feed power to the resistor) when the TS/DRL circuit stays on continuously for more than 1 second.
First generation will require a relay for each resistor but my source is working on a programmable delay relay with two independant triggers and output circuits.
Last edited by RC4G; Mar 5, 2013 at 05:12 PM.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
I had great success with 3M moulding tape for the resistors. It seemed to hold up very well to the heat.
Burning Brakes
Joined: Nov 2002
Posts: 807
Likes: 21
From: Los Altos CA
OK, I believe I've come up with a solution to only send power to the 6ohm resistors when the turn signals are active (not during DRL) and have sourced the required parts.
I will be building a mock-up off the car to test the relays this weekend (hopefully) and will post the solution when I have it fully tested.
Basically the solution is a custom relay upstream of the resistors that closes the circuit based on a programmable delay. This will allows the 6 ohm resistors to provide load during the turn signal flash duration but will open the circuit (no longer feed power to the resistor) when the TS/DRL circuit stays on continuously for more than 1 second.
First generation will require a relay for each resistor but my source is working on a programmable delay relay with two independant triggers and output circuits.
I will be building a mock-up off the car to test the relays this weekend (hopefully) and will post the solution when I have it fully tested.
Basically the solution is a custom relay upstream of the resistors that closes the circuit based on a programmable delay. This will allows the 6 ohm resistors to provide load during the turn signal flash duration but will open the circuit (no longer feed power to the resistor) when the TS/DRL circuit stays on continuously for more than 1 second.
First generation will require a relay for each resistor but my source is working on a programmable delay relay with two independant triggers and output circuits.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
Thanks for the input.
The relay I'm utilizing is programmable for both on and off delay of the circuit although in this application the on delay will be set to zero and the off delay will be set to 2 seconds.
The resistors are the same 6ohm/50watt aluminum cased resistors that all the LED light suppliers sell to eliminate rapid-flashing of turn signals when replacing filament bulbs with LED's. While 50 watts may seem like overkill rule-o-thumb sizing dictates that you size your resistor to twice your desire load.
The relay I'm utilizing is programmable for both on and off delay of the circuit although in this application the on delay will be set to zero and the off delay will be set to 2 seconds.
The resistors are the same 6ohm/50watt aluminum cased resistors that all the LED light suppliers sell to eliminate rapid-flashing of turn signals when replacing filament bulbs with LED's. While 50 watts may seem like overkill rule-o-thumb sizing dictates that you size your resistor to twice your desire load.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
UDATED 04/04: DRL resistor relay circuit mock-up successful
Successfully mocked up the circuit off the car just to make sure everything works as designed.
I've put a small red LED inline with the resistor so you can visually confirm when the resistor is receiving power from the relay.
The first 10 seconds shows the resistor LED flashing in unison with the turn signal bulb, showing that the resistor is receiving power and placing the additonal load on the circuit.
The 10-30 second section of the video show me flipping the toggle to light the turn signal circuit continuously as is the case during DRL mode. Notice that the resistor LED lights for approximately 2 seconds and then goes out each time I cycle power to the turn cignal circuit for more than 2 seconds in duration.
I've put a small red LED inline with the resistor so you can visually confirm when the resistor is receiving power from the relay.
The first 10 seconds shows the resistor LED flashing in unison with the turn signal bulb, showing that the resistor is receiving power and placing the additonal load on the circuit.
The 10-30 second section of the video show me flipping the toggle to light the turn signal circuit continuously as is the case during DRL mode. Notice that the resistor LED lights for approximately 2 seconds and then goes out each time I cycle power to the turn cignal circuit for more than 2 seconds in duration.
Last edited by RC4G; Apr 8, 2013 at 12:26 AM.
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas
Updated post #55 to show mock-up test with LED bulbs since a member questioned the validity of the previous test using an incandescent bulb.
Finally wired up the relay and resistors for installation on the car. The single black lead goes to chassis ground on the frame rails. The dual blue wire connection going to single connector will be connected to turn slignal circuit:
I have the parts list for bulb bases and socket housings so this circuit could be installed without splicing the B/W turn signal wire on the OEM bulb socket. I won't be installing them as I had already spliced the lead for the first LED installation (without the relay) and the vendor I used to get the 3157 bulb sockets sent me one 3156 socket by mistake when I ordered two 3157 sockets.
Finally wired up the relay and resistors for installation on the car. The single black lead goes to chassis ground on the frame rails. The dual blue wire connection going to single connector will be connected to turn slignal circuit:
I have the parts list for bulb bases and socket housings so this circuit could be installed without splicing the B/W turn signal wire on the OEM bulb socket. I won't be installing them as I had already spliced the lead for the first LED installation (without the relay) and the vendor I used to get the 3157 bulb sockets sent me one 3156 socket by mistake when I ordered two 3157 sockets.
Last edited by RC4G; Apr 7, 2013 at 11:28 PM.
Pro
Joined: Apr 2013
Posts: 700
Likes: 2
From: SC
The easiest way to confirm you are in DRL mode is when the front turn signals are on steady, and no other exterior lights are on.
Here are some pics of how I mounted my load resistors.
They have the typical integrated finned aluminum heat-sink and they are bolted to an additional heat-sink/mounting plate (pic 1) that has an air gap underneath to improve cooling (pic 2).
Then the load resistors/etc. are mounted to a canvas phenolic panel providing total isolation from the mounting surface of the car. (pic 3).
I know this is overkill, but I had the pieces/parts available and it makes for an easily-serviced install.
Here are some pics of how I mounted my load resistors.
They have the typical integrated finned aluminum heat-sink and they are bolted to an additional heat-sink/mounting plate (pic 1) that has an air gap underneath to improve cooling (pic 2).
Then the load resistors/etc. are mounted to a canvas phenolic panel providing total isolation from the mounting surface of the car. (pic 3).
I know this is overkill, but I had the pieces/parts available and it makes for an easily-serviced install.
Looks like a nice installation
Thread Starter
Melting Slicks
Joined: Aug 2002
Posts: 2,193
Likes: 195
From: New Caney Texas