Need help building LED floodlight

This might be a very simple project, but I'm very new to this and don't really know where to start. I don't even know what to search for to find my answers and the last couple days of reading hasn't helped much.

I want to build an LED worklight. I work out of my truck and want something that runs off 12v. I plan on using 12 Cree XR-E emitters mounted to a big aluminum heatsink I have. The problem is how to power them, they say 3.7v at 1000ma. My power source is 12vdc battery but could be as high as 15v. Could I just wire four emitters in series? or do I need a driver or something for them?

If it ends up working well, I would also like to build one that runs on 110vac. I'm done with halogens and the heat.

Thanks for your help!

Welcome to CPF, car54. I'm moving your thread to the Homemade & Modified section for you.

Running from auto 12, eh? Well, there are two inexpensize ways to do it.

The first is to run strings of three LEDs from this driver.

The second is to build something like this (you don't need any optics)

Running it from AC is more expensive, but can definitely be done.

I guess theres no way to run a bunch of diodes off a single board? That would be ideal, otherwise i think the drop-ins from DX might be the better route.

car54 said:

I guess theres no way to run a bunch of diodes off a single board? That would be ideal, otherwise i think the drop-ins from DX might be the better route.

Click to expand...

Each of those Kaidomain boards can run three LEDs in series. Running LEDs in parallel isn't suitable for long term use. Boards in parallel running LEDs is fine though.

I'm gonna try that board for the first attempt, but I'd like to be able to scale up to a larger number of diodes without having lots of boards driving them.

car54 said:

I'm gonna try that board for the first attempt, but I'd like to be able to scale up to a larger number of diodes without having lots of boards driving them.

Click to expand...

We may be talking about different things. You can run as many 3LED strings as you like.

I want 12 diodes, so with the boards youve shown, I would need four controllers driving three each, right?

Ideally, Id want to build one with 24, or more.. and I would need more and more controllers as it gets larger.

It would be nice to have one controller to drive all of them.. if thats possible.

If not, several of the boards will have to do! =)

car54 said:

I want 12 diodes, so with the boards youve shown, I would need four controllers driving three each, right?

Ideally, Id want to build one with 24, or more.. and I would need more and more controllers as it gets larger.

It would be nice to have one controller to drive all of them.. if thats possible.

If not, several of the boards will have to do! =)

Click to expand...

Even with one giant controller, I don't think you'll do better than $1/emitter to drive LEDs.

Good luck :wave:

This driver claims 5 leds in series at 1amp... sounds almost perfect for the drivers I have. Would something like this work as well as the 3-led driver from the link above?
http://www.national.com/pf/LM/LM3405A.html

Thanks! I'm asking because it is only $2.63 each from digikey.

car54 said:

This driver claims 5 leds in series at 1amp... sounds almost perfect for the drivers I have. Would something like this work as well as the 3-led driver from the link above?
http://www.national.com/pf/LM/LM3405A.html

Thanks! I'm asking because it is only $2.63 each from digikey.

Click to expand...

That won't drive any more LEDs than the KD driver. Neither of them can drive an LED string with a total Vf above the supply voltage. And does that thing require external components?

Here is a completed unit with 12 3 watt LED emitters. It may give you some ideas. Check out the others on this site. Warning...pricey!

http://www.magnalight.com/pc-1714-1...watt-leds--aluminum-housing--2160-lumens.aspx

http://www.magnalight.com/c-140-led-light-bar.aspx