Updating SMD LED from white to red

Hello. I’ve been racking my brain all day with this. Here is my situation and question:

I have some OEM ambient lights in my vehicle. They are all white, but I want to switch to red LEDs. I determined the are 3528 SMD LEDs, but the rest of the specs are what I need help with.

NOTE: My automaker sells a red LED alternative, but it is on the pricey side and I need several. From the pic I saw, it has an additional resistor along with the red LED. I presume it is to feed the red LED more power to give it more brightness since red is traditionally more dim than white.

Current measurements:

power source is 12V
current white LED is 2.54v
Resistor is 2.48 when DMM is set at 20k ohms

My questions are:
What specs LED should I be looking for?
Do I need to add another resistor, and what size?
Will this work (check pic of specs): KQO 100 Pieces of PLCC-2 Surface Mount LEDs, 3528 Size SMD SMT LED - Red, 100pcs Amazon.com - https://a.co/d/04fq99R


** I attached 3 pics of my current light, and one pic of the red LED board. **

I came across these online. Would these specs work without any additional modifications? And how would the output be compared to my current white LEDs?

PLCC-2 SMD Red - Ultra Bright 1210 / 3528 LED
Size: PLCC2/3528 - 1210 LED
Color: Red
Luminosity: 1500 mcd
Forward Voltage: 1.8-2.6v
Current: 20mA
Wavelength: 623-625 nm
Viewing Angle: 120 Degrees
MountStyle: SMD (Surface Mount Diode)

So, unless I'm much mistaken the light output from LEDs depends largely on the forward current. That 1500mcd will be with them maxed out at 20mA I suspect... driving them at their maximum for long periods will shorten their life.

I believe with the resistor you have on the board, the current LED is being driven at somewhere around the 4mA mark. So, I don't think you'll get the stated light output from the reds, but then you're probably not getting the maximum from the whites either.

Unfortunately red on it's own always looks dimmer than white, that's one of the reasons to choose it... you can still see things, but it's not as intense as white light. If it were me, I might be inclined to try and source a few of the red LEDs from a reputable supplier (somewhere like RS for example or CPC) and give them a whirl. You may find that paying slightly more for them from RS et al. yields a better result as they are likely to be a slightly higher quality product and may well be better matched in terms of their brightness.

Thanks. I figured the “Forward Voltage: 1.8-2.6v” was the key spec that would allow me to do a direct swap since the current white LED measures 2.54v with a multi meter.

Wouldn’t that just run the red LED at the optimum range without it getting too hot?

Keep in mind these are ambient lights. I want to keep it the same intensity as the white LEDs, just trying to avoid it from looking too too dim.

JC_RH305 said:

Thanks. I figured the “Forward Voltage: 1.8-2.6v” was the key spec that would allow me to do a direct swap since the current white LED measures 2.54v with a multi meter.

Wouldn’t that just run the red LED at the optimum range without it getting too hot?

Keep in mind these are ambient lights. I want to keep it the same intensity as the white LEDs, just trying to avoid it from looking too too dim.

Click to expand...

The key figure is the current. That is what you need to keep under control.

DPG said:

The key figure is the current. That is what you need to keep under control.

Click to expand...

Thanks. My understanding is that most LEDs in general are 20mA. So does that mean I should be fine, or not enough information based on what I provided?

JC_RH305 said:

Thanks. My understanding is that most LEDs in general are 20mA. So does that mean I should be fine, or not enough information based on what I provided?

Click to expand...

They do vary a bit. You'd only know from checking the datasheet though.

So after doing some math based on my current setup, should I ADD an additional resistor labeled “2491?” It looks like I need about 500-ohm resistor. From what I can tell, the resistors are setup in parallel (see pic that is backlit.) Correct me if I’m wrong.

Also, based on my pic (3528 LED), what size/model resistor should I be getting?