Need help with some electrical work for interior LED lights
 

Hello everyone,

I would love it if you guys could help me with a bit complex project.

So I want to install 3 things inside the cabin: LED interior lights under the footwell, LED's on the door, and fiber optic lights in the headliner.

Here is a link for the footwell and door lights:
[ame="https://www.youtube.com/watch?v=yOW6qsGQLtA"]BRZ Ambient lighting Installed - YouTube[/ame]

I want the same style but unlike in this video I don't want to buy the Subaru illumination kit ($150). I would rather install all those myself with some switches




And here is the link for startlight (fiber optic in the headliner)
[ame="https://www.youtube.com/watch?v=IsqOd5xyQXQ"]Fiber Opitic Star Ceiling - YouTube[/ame]

link for the actual fiber optic kit:
http://www.ebay.com/itm/Car-DC12V-7W...-/151569668575


So, I am planning on having 3 lighting (footwell, door, star) with independent switches for all 3 (so i can turn them on and off independently. So far easy)

The part that makes all of this complicated is the following 2 things:

I want the footwell and door LED lights to draw the power from the dash so the dash dimmer switch also dims those LEDs and when the dash is off those 2 lights are off as well. But the startlight to draw it's power from a fuse box that i have installed (for my radar detector and dashcam) that outputs power only when the car turns on. (I could wire the starlight the same as the other 2, I am still debating on this)

I also want all 3 of these to draw a separate line of power from the dome light, so when I open the door all the lights in the cabin light up (regardless of those switches that i installed) --- I am planning on achieving this with use of schottky diodes on those power lines (correct me if this is the wrong way of doing that).

I wanted someone with experience in lighting to look through this and tell me if this idea could work.

Concerns:

• the amount of power that it will draw from the dash and dome lights won't affect the dash and dome light in a negative way

• when both switches and the dome lights are on would that output too much power and damage the LEDs

:thanks:

In before totaled :popcorn:

Wiring this sort of thing is rather easy. Just find an unused power source that is not used by anything else and is always on with the ignition on (there is one in the engine fuse box I can confirm). Then wire them all up to that add a switch and enjoy it for a few days before it starts to annoy you the either rip it out or never turn it on again.

Edit: Also I dont think those cheap Canadian tire/ebay LED's just dim when wired to the dash dimmer

This doesn't address all ops concerns. I don't know anything about total power draw and such but for the dimmer, just tap into an output wire on the dimmer switch(use a volt meter to test). Then additionally hook them to the dome light so it will take power from both sources

I really dont think they will just dim by hooking them up to the dimmer and give 2 separate 12v sources to the LEDs will burn them out.

I dunno, I don't know much about electrical. Assuming they don't burn out, my way would work. If the LEDs don't like the low (?) Voltage of the dimmer then they will cook. However... I have a display case, lit by LEDs with a dimmer and they work fine. So maybe it depends on the kind? Are they're different kinds?

Yeah I also think it has to do with the type of LED if they can dim or not. I tried to get my gauge to dim the the lights but I could never get it to work. I dont think the dimmer switch in our cars is a rheostat I think it just tells the computer that the driver wants the lights dimmer and the computer dims the lights on the dash.

If this is the case he would simply have to install a separate dimmer switch instead of or in addition to his on/off switch

Haven't read entire thread yet, will do on Monday probably at work, but solid state relays are your friends

ok, I have read a bit more.


So I would still recommend using solid state relays with the LEDs as drivers
LEDs dim by having a duty cycle on a pulse width modulated (PWM) signal. this means they turn on and off really fast on a % cycle, so 30% brightness means they are on 30% of the time.
looks something like this
-___-___-_...


Anyways, using a solid state relay allows you to safely extend a PWM signal from a controlled source, namely the BCM which controls your dome lights and clusters, to more LEDS without worrying about their current draw beyond what the relay can handle which will be a lot more than the BCM can.


I have all my aux LEDs run off the dome light circuit, using a solid state relay grounded to the dome light with a switch and resistor in line. When it completed the LEDs get powered directly from the battery. Use a solid state relay, not a traditional, PWM will destroy a traditional relay in about 4~10 uses in my experience.




Afterthought:
The most important part of this is to measure your current use on any circuit that connects to the cars computers. I did this by measuring the current draw from the standard bulb and doing math from there.
although really.. there's no reason you couldn't throw a 10k resistor on there and the same setup would work.. but for the sake of sciences and safety you should prob measure your components.


Use fuses. if you wire something backwards, like a diode, your wallet will be thanking you

One more thought, you almost certainly want to use ground control logic for the circuit you suggest in which you have multiple ways you want it to light, using relays you can have power and ground for the LEDs themselves independent from control logic, so no worry about power draw on the LEDs, then on the control side you would just have more than 1 path to ground with diodes and resistors, and switches if you so choose to control that side.