LS heatsink and wiring question *Moved to Electronics Forum*

Do any of you use the heat sink as ground for your electrical connections? I read somewhere that the negative wire gives off the most heat. So I was wondering if there would be any advantage to this.

I'm planning on using the head from a Legend 2AA for cooling in a headlamp mod, but it's small, so I need maximum cooling.

The heat sink is electrically isolated from the actual die and its connections. So it doesn't matter what you connect it to.

The negative wire does not give off any more heat than the positive wire, unless its smaller and cant handle the current. Technically current flows from negative to positive, but that really does not affect anything. In my experience at installing high end car stereo systems I run into a lot of young kids who think you need a big power wire for an amplifier(like 8 gauge or so) and a piece of speaker wire is good enough for a ground wire. In that case the ground wire will get hotter , until the amplifier dies, because it can't handle the current

i think it's that the heat caused by the creation of light is directed down the negative terminal more than the positive one, it's not because the leg is smaller...since the clear lense is plastic or resin or something it doesn't conduct very well and the heat is shunted down the negative lead...this is about 5mm and 3mm 'traditional' LEDs, i'm not sure if it holds true for luxeons...

but, anyways, all of these mods that use a heat sink that touches or is wedged to the metal body of the flashlight housing are all grounded because the battery negative flows through the housing...

Although in the LUXEONS that are mounted on a "board" / heatsink, the negative terminal on the PC is insulated from the heatsink, in many of my mods and "scratch built" lights, I run the negative connection to the ground/heatsink for two reasons:

1. it can make hookups easier. (unless you have one of the light designs that has positive ground)

2. the negative (Cathode) IS the heat sink in *most* if not all LEDS- (Craig- correct me if I'm wrong on this.)

You can actually feel the difference in temperature of the different leads on a Nichia.

On the Luxeon emmitters, The heat sink slug IS electrically connected to the negative terminal. That is why if you "zap" your board/heatsink mounted LS/O, very often you can resurrect it by removing the emitter from the "board" and use the heatsink slug as your negative connection.