I'm a Total Newbie Idiot - LED problems

[LED-Idiot]

Hi Guys, Any help would be greatly appreciated...
Just getting into this LED stuff and I know absolutely nothing about it.
A couple of years ago, I wired up my old car with glowing decals and under seat effects, but it was all wired into a controller with batteries.
I hated that...having a couple of double AA's in a controller underneath your seat is just so amateur, so Ive been trying to get into things via wiring it into my cars actual electrical system...that being said, I have some LEDs that work and some that don't...

So, before I begin, I just want to say that all the LEDs actually work - Ive tested them using my old controller and they're all fine - they all light up using it - Its just some work and some dont when I wire them into my car.

Okay, so I got me a Fuse Tap - wired them all up and grounded them as youre supposed to do - and I've tried doing them all individually - and only one out of the three will work...Ive dug through forums, tried different fuses, different plugs different wires, etc. etc. - Im at my wits end...what am I doing wrong?
Im trying to plug them in to my instrument panel - its a 90s sportscar, so it has a nice little old school on-off, dimmer switch for the instrument panel... In any case, out of the three LED's I have - only one will work when tapped...the rest do absolutely nothing - Im doing all the same things with all of them, but still, only the one will work...I mean, theyre all supposed to be 12V...they should all work the same, right?!?!
Thoughts?? and please, talk to me like Im dumb because, when it comes to this stuff, I really really am apparently...just clueless at this point.

OH, and last but not least, some of these LEDs I bought months ago and just had them stored, so I wanted to test them to make sure they work - before I remembered I have a battery powered controller...I used a lithium battery and I have the same results - only the first one worked - the others, not even remotely....


So, that being said - thoughts? How would you guys go about wiring up - multiple LED's to that fuse tap that would actually work?
I dont want a huge amount of effects- I just want some of those tube LEDs running up my doors and around my dash, a couple of the #2 style LEDs under the dash to light up the floor, and a wire (probably attached to a key ignited electrical source so that it runs whenever the car is running) to the front of the car to illuminate my front decal...


Again, any help would be greatly appreciated....Im so so soooo out of my element here. I feel like a total idiot.

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[DIWdiver]

In a 90's era sportscar, I would guess the dash lighting is with incandescent bulbs. The dimmer changes the voltage to the bulbs, and that varies the brightness.

LEDs don't work the same way. LEDs go from off to on to burned out in a very small range of voltages. If you had an LED that drew rated current at 12V, then at 9V it might draw very little current and light dimly or not at all, while at 14V it would draw so much current you could fry it in a hurry. Worse than that, it would draw more than rated current at 12V when it gets warm (or hot) and less when it's cold.

This is why LEDs should be driven with current control instead of voltage control. When you put the rated current through the LED, the voltage will be predictable within a fairly small range. When it gets hot, the voltage will drop a little, when it gets cold it will go up a little. Thus you have much more precise and predictable control over the power you put into the LED.

I'm guessing you have two LEDs with somewhat higher voltage than the other. The low voltage one works, but the dashboard voltage doesn't go high enough to light the other two. When you put them on the other controller, they all work because the controller controls the current, and lets the voltage go as high (or low) as it needs to (within limits, obviously).

You could prove me right or wrong if you could measure the voltage across the LEDs when on the controller, then measure the dashboard voltage.

All LEDs work this way, but not all LED lights do. Your LED#1 looks like it's probably a 3V led with a series resistor (the resistor is the blob under black heatshrink). This would make it work much more like an incandescent bulb, starting to light around 3V and getting brighter and brighter as the voltage goes up. If you measured the voltage across just the LED, it would start to light around 2.7V and by the time it is fully bright, the voltage would be 3.3-3.6V. All the remaining voltage would be across the resistor.

Most blue or white LEDs are actually around 3-3.5V. To get higher voltages, you string them in series. With 3 in series, you'd get 10-ish volts, for higher voltages just string more in series.

I can't tell exactly what LED#2 is, but I'd guess its either 10-ish, 20-ish, or 30-ish Volts with no resistor. I have no clue what #3 is.

 

[LED-Idiot]

DIW Diver-

Thanks so much for the response - seems like everyone Ive spoken to has just been completely at a loss as to why these will not work.
I even contacted the company where I bought them, and I have them scratching their heads - as everythign was supposedly rated for 12V in a vehicle.
In any case, the one on the very right is a string tube LED - like this:

I suppose my best bet then would be to just get a battery powered controller, and just use that...I was really hoping to tap into the car battery but I guess that's just too complicated for this fella to figure out. Either that, or Ill have to find a controller that I can power via fuse box.
Thanks again!