led/smd rear/tail lighting board problem

[Rugrat]

Hi,

I apologize if I have posted this on the wrong page. I have recently bought a set of rear lights for my truck. The leds are not very bright though. Would it be possible to change them to brighter ones? The truck is on a 12v circuit and there are 45 leds per side so 90 total. I assume that the resistors drop the voltage? Could I replace the resistors with wire and put in 12v SMD's? The maximum diameter is 5mm, but i can easily drill the holes out to 7mm and the maximum height would be 25mm from the circuit board as the cover gets in the way. Also what is the best way to remove and replace the leds, I only have an antiquated soldering iron which I used to remove one of the leds to see if it had any info on it and it was not easy.

Any help and advice is welcomed as i have a very limited knowledge on this subject. Thanks.

 

[Harald Kapp]

Could I replace the resistors with wire and put in 12v SMD'

No, LEDs need some form of current limiting. Without they will quickly blow. Read this resource for detailed information.
You can try to replace the present LEDs by so called high brightness LEDs. A good soldering iron will help you not to destroy the LEDs when soldering.

 

[RRITESH]

Hello,
using led is very simple.
You have to make led glow.
use ohms law which is V=I*R
Vs=Vled+Iled*Series
where V is supply voltage which 12V and Vled is voltage drop across Leds and I is current controlled by Series
so, if white led 3.2V and red led 1.9V so, current should be ~20mA depend on brightness you can get from LEDs
if there are two led in series the voltage drop will be 3.2*2=6.4V for white.
and 12-6.4V=5.6V
so, 5.6V= 20mA*R
R ~280ohms

 

[Rugrat]

No, LEDs need some form of current limiting. Without they will quickly blow. Read this resource for detailed information.
You can try to replace the present LEDs by so called high brightness LEDs. A good soldering iron will help you not to destroy the LEDs when soldering.

Harald, thanks for the link and reply. Is there any way I can tell if the ones already installed are high brightness? Is this just a case of cutting my losses and finding something better?

 

[Harald Kapp]

Is there any way I can tell if the ones already installed are high brightness?

Probably only by comparing the intensity to 'real high brightness' LEDs at the same current.

Note that the lights on an automobile are subject to strict regulations. Manipulating the lights, especially using non certified components, may result in loss of the license for using the automobile on public roads.

 

[Rugrat]

Probably only by comparing the intensity to 'real high brightness' LEDs at the same current.

Note that the lights on an automobile are subject to strict regulations. Manipulating the lights, especially using non certified components, may result in loss of the license for using the automobile on public roads.

Thanks Harald.

Is there any other ways to incorporate a brighter light into the unit? I think the ones in it already are the ultra bright ones.

 

[Harald Kapp]

You can try and use series resistors of a lower value to increase current. You risk shorter lifetime of the LEDs, though.

 

[BobK]

1. Have you tried powered them from 14V which is about what you will get when the truck is running?
2. How many resistors are there? It looks to me like there must 3 or 4 LEDs for each resistor, which means that the difference between 12V and 14V could make a large difference in brightness.
3. How much did you pay for the lights? 90 higher brightness LEDs might cost you more than buying a better on in the first place.

Bob

 

[Rugrat]

1. Have you tried powered them from 14V which is about what you will get when the truck is running?
2. How many resistors are there? It looks to me like there must 3 or 4 LEDs for each resistor, which means that the difference between 12V and 14V could make a large difference in brightness.
3. How much did you pay for the lights? 90 higher brightness LEDs might cost you more than buying a better on in the first place.

Bob

Hi Bob,

There are 4 leds per resistor (approx). Please see (the program seems to crop the width) photo. I searched on line for '90 higher brightness leds' but got no results. Could you post a link? Thanks for your time

 

[Harald Kapp]

E.g. here.
Search terms for Google, Bing etc. are 'high brightness led 5mm red' (I assume you'r are red LEDs).

 

[Rugrat]

E.g. here.
Search terms for Google, Bing etc. are 'high brightness led 5mm red' (I assume you'r are red LEDs).

hi Harald,

thanks for your help I have ordered some more leds and will see if they are better.