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Discussion Starter · #1 ·
I thought I would share a bit more detailed information about load resistors that are needed if anyone is putting LED into their turn signals.

While in some cars you can put LED ready turn signal relay, in 2014+ Forte the blinking is controlled by BCM. Hence, you must add load to the circuit in order for the system to not think light bulb is burnt.


The problem here, when I read here and there, is a confusion with load resistors specification.
There are two parameters that they carry.
- resistance
- power dissipation

The former is given in Ohms (6 or 8 Ohm are most common) while the latter in Watts (25 W or 50 W).
Now, the resistance makes the load (not the power!). The resistance must be chosen based on "missing" power load from installing the LED. The power specified on the resistor is nothing more, but the MAXIMUM power it can handle. However, one should keep in mind that while this is the maximum power, the safe limit is half of that.

The confusion gets from reading the specs and comparing to your setup.

In short example.
Rear turn signal is light bulb model 1156. It is rated 27 W at 13.2 V. That gives you resistance of 6.5 Ohm at current of 2.05 A.

More detail
Resistance remains (basically within some limits) constant, so at 14.3 V (when engine is running) you will get 2.2 A and power will be 31.2 W (that's why they are righter when engine is running), or when battery is low at about 12.0 V power is 22.3 W and current 1.9 A.

Going back on track.
LED in this example will be 2 W. This MUST be measured. Do NOT believe in LED that are 15 W. If that was true 15 W, then it would need to have a big heatsink. You must use multimeter and measure current being drawn by this LED. Having current and battery voltage you will find out what is its power. Current x voltage = power (AxV=P).
So, you got 13.2 V, 0.15 A. power is 2 W.
Tungsten is 27 W, minus LED 2 W - missing 25 W.
Now, take 25 W and convert to Ohms!!

25 W at 13.2 V will create current flow of 1.9 A. 13.2 V/1.9 A = 7.0 Ohm.
You know now that the resistor must dissipate heat of 25 W and its resistance should be around 7 Ohm.
Common sizes are 6 Ohm and 8 Ohm... what's the difference?
6 Ohm will produce more power (will allow more current flow) and at 13.2 V will have 2.2 A resulting in 29 W.
8 Ohm at 13.2 V will pass 1.7 A and produce 22 W.
Either one is good.

If possible, 8 Ohm would be a better choice due to the fact at 14.4 V (engine running) it will be more about 26 W... so basically ideal load.

To keep it safe without extra heatsinks - the dissipated power must be doubled. Hence, load resistor should be of 50 W. This way it will not be glowing red when under load...



In very short.
In any LED setup, for one side, one LED bulb, you will need 6 Ohm or 8 Ohm resistor of total power 50 W (or more). If you choose 25 W, you MUST add heastinks.
 
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GREAT write-up.
So do you have a "How To" for a LED setup?
Thanks
 

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Discussion Starter · #3 · (Edited)
You are welcome.

I am about to do that. I will add it here.
I got Osram amber LED. So far those are the best I could find. Philips offers street legal (the only certified LED replacement I found) that could be used in tail lights (tail and stop). Osram is still off-road only...
They are 1156 and 1157 white and red. My point is to get the turn signals AMBER which can be accomplished with amber LED behind red lens.
I got Philips as well for my other car and I must say - they are very good.
Still they lack a bit of brightness, but they are far superior comparing to all "super high power LED". Plus, location of the LED chips exactly mimics filament in tungsten light bulb. Tower LEDs were a big mistake...


Look here

https://www.amazon.com/SYLVANIA-ZEVO-1157-Amber-Bulb/dp/B01A77TQ2S

https://www.amazon.com/dp/B00P2D415..._m=ATVPDKIKX0DER&pf_rd_r=00PY6GCPNAWTTXQ50EVQ


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Product Automotive lighting Font Circuit component Audio equipment
 

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I'm sure this has been beaten to death already but what about the EP flasher? Thoughts on that? I know I've seen a bunch of 1st gen forte users using it instead of wiring in load resistors, wasn't sure about the 2nd gen crowd. Would love your input!
 

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Discussion Starter · #5 ·
I'm sure this has been beaten to death already but what about the EP flasher? Thoughts on that? I know I've seen a bunch of 1st gen forte users using it instead of wiring in load resistors, wasn't sure about the 2nd gen crowd. Would love your input!
I mentioned it up there. In the second sentence.
The flasher will not work in this one. I do not have a solid proof (like a schematics), but from my tests it appears the relay is built into BCM. You see, if it was the typical flasher, like it is in my 2007 Rondo or my previous 2009 Elantra, I could use Tridon EP34. I did it with Elantra and it worked great except the flashes were too short and too quick.

In Forte, though, I found that if I put LED instead of tungsten, the first two flashes are normal, but then it goes into hyperflash. Happens on both sides and the same pattern. If it was regular relay, hyperflash is instantaneous. At least that was with Elantra. Relay would respond right away.
I guess it takes a moment for CANBUS to realise there is not enough load.
 

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I mentioned it up there. In the second sentence.
The flasher will not work in this one. I do not have a solid proof (like a schematics), but from my tests it appears the relay is built into BCM. You see, if it was the typical flasher, like it is in my 2007 Rondo or my previous 2009 Elantra, I could use Tridon EP34. I did it with Elantra and it worked great except the flashes were too short and too quick.

In Forte, though, I found that if I put LED instead of tungsten, the first two flashes are normal, but then it goes into hyperflash. Happens on both sides and the same pattern. If it was regular relay, hyperflash is instantaneous. At least that was with Elantra. Relay would respond right away.
I guess it takes a moment for CANBUS to realise there is not enough load.
Gotcha! I read through your post quickly. Makes sense though, at the end of the day having to install load resistors isn't bad, just a bit of a hassle for some

Sent from my XT1585 using Tapatalk
 

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Discussion Starter · #7 ·
Gotcha! I read through your post quickly.
No problem.

at the end of the day having to install load resistors isn't bad, just a bit of a hassle for some
It is for me... I mean, not a hassle, but I just hate putting them, but so far I did not find any other resolution.

A relay would be much better. Especially if you could adjust rate of the flashes.
 

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i still dont feel LEDs have the umph to be safe unless the light housing itself is specifically designed for LED usage.... hence the reason OEM's dont use just a single bulb and make entire light housing out of LEDs instead...

but to each his own......
 

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i still dont feel LEDs have the umph to be safe unless the light housing itself is specifically designed for LED usage.... hence the reason OEM's dont use just a single bulb and make entire light housing out of LEDs instead...

but to each his own......
I would check out our 80 W CREE bulbs against the competition, these things are extremely bright.
 

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Discussion Starter · #10 ·
I would check out our 80 W CREE bulbs against the competition, these things are extremely bright.
Could you elaborate on 80 W?
On a side note, brightness has not much to do with light intensity...
 

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Discussion Starter · #12 ·
I would check out our 80 W CREE bulbs against the competition, these things are extremely bright.
I will repeat my question as it has not been answered.
When you say 80 W, what do you mean?

As for them very bright, I will elaborate. Bright will be say 2700 K new tungsten light bulb vs 4100 K new LED. 4100 K is bright (whiter, clearer light). But light intensity is in question. How much light will I get trough a red lens? The multi chip LED will produce what lumens? And I am talking about measured lumens, not theoretical from LED chip specification.
 

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Could you elaborate on 80 W?
On a side note, brightness has not much to do with light intensity...
80 Watt CREE is the name of the product itself that we sell. I'm sure that is the max rating of the bulb rather than the standard running wattage.

80w compared to 26w for a Sylvania bulb?
Great question, we're open for a comparison if you have those now and would like to test ours side by side.

I will repeat my question as it has not been answered.
When you say 80 W, what do you mean?

As for them very bright, I will elaborate. Bright will be say 2700 K new tungsten light bulb vs 4100 K new LED. 4100 K is bright (whiter, clearer light). But light intensity is in question. How much light will I get trough a red lens? The multi chip LED will produce what lumens? And I am talking about measured lumens, not theoretical from LED chip specification.
I do apologize, I haven't had as much time to jump on the forum lately. These are some great questions, & to be completely transparent, I do not have an exact number to provide as you have requested as the product is still relatively new.

We also do not do testing of the exact lumen output here at our facility as we do not have the proper equipment to do so, however we are very pleased with the light output of these bulbs and would be happy to offer discounted pricing on them to anyone wanting to test them out or compare them to their existing setup. We have sold quite a few sets of these since they came out. We also offer a 30 day return policy on the bulbs if you buy them and they are not what you were expecting or you're just not happy with them.
 
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