[DIY Project] 10-30W (1000-1800lm) COB LED portable work light

Hi guys,

I’d like to present you one of my ongoing projects. It’s supposed to be a portable worklight based on a 10W 1000lm COB LED stuck on a nice big radiator. The project is now in “alpha” phase, meaning it only has:

-Custom PCB
-Boost module, I will run the LED at 13.5-14.5V to give about 1800lm. I ran that LED at 40W without a problem.
-Mini LED dimmer/controller. All kind of modes(strobe, pulse, etc), super easy dimming, power on/off.
–40mm Cooling Fan
–75oC NC thermostat with a relay to basically make it NO and power on the fan when the temp hits 75 degrees, not cut it off.
–100oC thermostat that shuts everything down when the temp is reached(I don’t think it’s going to happen, but hey… better off than sorry)
-Power LED. Blue, ran at 3.5v from the 12v input via a 470ohm resistor.
-Thermal warning LED. Red, same thing, it kicks in when the fan does.

http://imgur.com/a/poEM6/embed

Here’s a video with the first test.

What’s next:
-Shrink the PCB to 1/3 of the current size to fit it on the back of the radiator.
-Move the 100 degree thermostat near the LED so it only cuts it off, leaving the cooler on so it will eliminate heat faster.
-Custom case made out of Plexiglass, with 5.5x2.1mm DC power plug
-Tripod screw at the bottom for “nearly everywhere” fixing
–3-4x18650 attachable battery pack that simply plugs into the DC female plug when connected.

The biggest problem will be to shrink the PCB.

don’t know how well you will progress from now on, but nevertheless what i see i like it :slight_smile: nice project .

Cool projekt.
I am a bit confused by the numbered do you overdrive a 10W LED? Which led did you use?

Got a schematic…Mattaus is a master of PCB from OSHPark…not sure on international shipping…

Awesome build though…great job!

Thanks! Sorry, I was able to read all your replies but never found the time to respond until now.

The LED is a thick COB (~20mm wide), 10w 1000-1050lm unit that I really don’t know where I got from. I had it for some time. Either DX, either buyincoins… Anyway, you can find LEDs like it easily. They should be about $5-8. Same for the narrower, 10mm wide ones. But I like this as it’s dissipating heat more effectively.

At 14.5V it draws about 3-3.3A, so about 45W. The thing is that the efficiency is almost non-existent at that voltage on direct drive. The light output compared to ~13-13.5V @ 2A is almost the same. The rest of 15W is mostly converted to heat, not light.

The light scales pretty linear to about 20W, so let’s say it will pump out ~1500-1600lm. If I go to 30W I think I get 1800lm. Not really worth it, but I can dim it easily if needed.

The step-up module output voltage is not fixed, but I think I will go for 13.5V.

Thanks! I see the shipping is free, but I think I can do it myself. I mean I’m positive I can, I just need some time to rethink the mini circuit, because it has to be organized differently. Also, the parts are cheap. Like dirt cheap. A one-sided, blank copper PCB of the size you see in the photos costs me about $0.3-0.5. A 500ml bottle of ferric chloride is $1. Actually, the waterproof Edding marker I use to draw the circuit is the most expensive of them all, at a whopping $2.

It’s not hard, it’s just time consuming for me now because that was my first PCB and my mind isn’t yet “set” on resolving “puzzles” like this. With a bit of practice I will be able to do them faster.

I just wonder now where was my mind when I put the 100degree thermostat at the power input… It should’ve been so clear to put it on the LED, so the fan would continue cooling it off in the meanwhile. Well, at least I can fix it and improve it as I go.

L.E. Let’s add another thing to the to-do list. 12v “on-click” battery charge meter.

Please add a picture of the led.

I did some more tests, this time with the 3x18650 Battery Pack. The good news is that even with the Battery Pack’s V-Drop when the LED is at maximum power(from 12.6 to 11v), the relay coil still triggers. If it wouldn’t trigger, I would’ve lost functionality of the first thermostat, and the fan would be forever on. Anyway, even with a V-Drop to 7.5-8v when the batteries are almost dead, it still triggers. This is good news.

However, I’ve gotten some strange measurements when checking the power efficiency. I compiled a table and graph with measurements at the battery pack, and at the LED, checking the voltage and current through each of the 7 steps of the dimmer.

The dimmer used is a mini-dimmer from eBay, that I can quickly go through modes. I honestly don’t think it is causing this huge loss in efficiency, but actually the little step-up module that gets quite hot when the dimmer is on full power mode. It does eat up 3A then. At very low power, we have the relay coil that’s eating up power, and also the power-on led(20mA). The Step-Up module is rated at 95% efficiency, but I don’t really eat this up as true.

I have to measure the LEDs with my big power supply and a heftier step-up module that I have, and see how it fares then. If it does good, then I’m changing the boost module with the larger one(rated at 10A).

The LED used for this test was the thinner one in the following album, as it’s more power hungry(I wanted to push the system a bit). Still “10w”, but I think it’s rated at lower voltage. The thicker one is the one I will actually use.

http://imgur.com/a/CkmgA/embed

As a conclusion, I have to see how much the LED’s consume a perfect environment with enough headroom from the power supply, then compare to what they do in the setup. I’m annoyed that at max power, only 71% power consumed actually goes to the LED.

P.S. I have small, square, 12v 10W leds that at 14.5v eat up 5A. Yes, 70W. They heat up like the door to Hell is opening beneath, but still admirable. Maybe I’ll use 2-3 of them because of the efficiency (@ 12v would mean 3000lumens) . The problem is that I don’t have 6000k, only warm white. The 6000k’s were lost in transit and I have to reorder them. :frowning:

Ne updates