Interior LED lighting

** Added 14 June 06 - I am now officially selling this modules. See Sales Thread. ***

I know that several folks have been interested in some of the LED projects I've been doing on the Prius, so I figured I'd better start a thread to keep it all in one place. I have currently achieved LED nirvana, in that all interior lighting in my Prius is now via LED... and I've added some where there weren't lights before.

My plan in showing these now is NOT to take orders or answer the "when will these be availble?" questions. My goal is to show what I've been up to, and see if anybody has any input or questions that will lead to some useful product. I REALLY wanted to create some "drop-in" modules for the Prius, but that is proving quite difficult. I do have one for the cargo light - which is nice since that one won't ever time out... and can definitely benefit from more photons!

The Prius interior uses three different bulbs, and has four different fixture configurations. There is no ONE Prius LED replacement solution, unfortunately! In each instance of my replacement, I increased the light out put, and reduced the current draw. The conversions I make are spike-protected, and fully current-regulated. No, you cannot buy these from China for $2!

OK, I'll stop rambling, and start posting links...

 

cargo LED
front dome LED
rear dome LED
door edge LED
cup LED

 

Oops. Fixed now. No, no. I only put links to stuff I've done.

 

Have I looked at any?! I have many hundre$ invested in commercial products. Since I never found a single thing worth a damn, I decided that I had to make my own. The Chinese stuff you see for sale has one advantage: It is cheap.

They are not regulated, the tint is crap (usually quite blue) they're over-driven and will have terrible efficacy, and they're too dim!

What I'm doing here is BRIGHTER than the factory bulbs, is fully regulated, has a premium tint, is driven at or below spec for an expected lifetime of several vehicles. I don't do well with "adequate." That said (with as much bravado as I can muster) I am trying some of the new stuff that Chris has on his site (superbrightleds). I've dealt with him plenty in the past. He has one product that may just be our best bet for the rear dome. If it is, I'll see if I can buy a bunch of them for us.

 

You still beat me by most of an hour! A guy has to eat.

 

Errr. It wasn't a "find". My EE buddy George designed this original circuit, and we have refined the physical design over the years to optimize it for the most universal application. We both use it for various products, and between the two of us, we have almost 1000 of them in service now. The circuit was designed from the beginning to *specifically* drive a Luxeon, so I'm not really sure what you mean about being aware of that capability. Are you familiar with the CC1W driver? It'll drive other 1W LEDs as well, but is currently sized to fit the Luxeon Star heat sinke perfectly. The circuit is being redesigned as we speak. The result will be a slightly smaller board that is specifically aimed at automotive voltages.

 

Gotcha. And howdy... I'm an Admin on CPF, if we haven't met. Interesting that you call it an LED forum. It is a "light" forum, and there are still many people who are happy with the hot wires. Just not people like me.

 

Hey! The cupholder is like the ONLY thing that anybody else notices!

 

Good question!
And yes... as you may have guessed, there are a few VERY good reasons to use current regulations. I wouldn't build automotive lights without it.

1. Constant light output. Without current regulation, the lights will be dimmer when the car is not running, and quite a bit brighter when it is. With current regulation, the output is consistent regardless of what the car is doing.
2. Control of the current that the LED sees. For good efficacy, the emitters should not be over-driven. Without regulation, your only choice is to underdrive the LED most of the time in order to safely account for the times of over-voltage. Result - significantly less light most of the time.
3. Severe V spikes found in all automobiles that we've tested. Without regulation, the emitters can see voltages well over the Vf of the LED. (Ok, this isn't much different than item two....)

This circuit can handle up to 30V input... and that is not by accident! Automobiles do all kinds of crazy things with Voltage. The AVERAGE is 12-14V, and that is what most meters will show all the time since they're dampened. But that's not what's really happening! We have destroyed circuits that can handle spikes to 20V+... and that would have destroyed any resistored LED as well.

Yes, you can build somthing very cheap with resistors. Just like you can build a cheap car without a HSD. I won't waste my time with that stuff though. There's already tons of it on the market.

I have yet to figure out the advantage of the "dimming" buisiness. I know that many people like it - and I did at first too. Some folks would rather die than lose it though! Yet to my knowledge, everybody who's switched over to something like this has never missed it. You only seem to notice it when it is there. When it is gone, it is just gone.

 

Short answer:
The cheap/easy way will waste lots of power and get WAY hot. Seems simple, but won't work.

These things aren't complicated just for complication's sake!

The long answer:
Yep, it could be done with a voltage regulator and a resistor - it would get HOT. The reason CC1W (the cuircuit I've used) is oh so complicated looking is because it's a switcher and converts DC to DC and regulates the current to boot. 350mA Luxeon through CC1W draws about 100mA from 12.8V (and less at 14.4V).

A regulator/resistor would have to burn 14.4V - 3.3V (assume 3.3V Vf) at 350mA. That means 11.1V x 0.35A = 3.9W of heat having to go somewhere.... Plus the 3.3V x 0.35A of the Luxeon. A total of 14.4V a 0.35A = 5W of heat going somewhere...

CC1W at 14.4V and driving the same Luxeon would be drawing about 0.09A. So, 14.4 x 0.09 = 1.3W total (Luxeon + CC1W).