That’s a $67 Bridgelux C9000 array (cool white), $8 Intel copper CPU heatsink/fan, and a $6 150W Chinese DC-DC converter (modified for constant current output ). The DC-DC takes 10-30 volts in and outputs 5A at up to 35V out. I’m driving it right now at 15V, 12 amps. Even with a rather crappy power fet, it is around 88% efficient… who say’s boost converters can’t be efficient? A decent FET should get the efficiency up over 90%
You get:
It starts out at around 16,400 lumens and falls to around 15,300 lumens after 3 minutes (the heatsink does not quite fit in my sphere’s input orifice and I am losing around 1400 lumens in the transition). Note that the LED output is actually increasing over time.
The color temp numbers are bogus since the color sensor is saturated. The LED numbers are not valid since those sensors are not connected. The BATT numbers are the LED voltage/current/power.
It is driving the LED at 162 watts (30.7V, 5.3A). That little Chinese Dc-DC boost converter actually works rather well. The little heatsink fan is a screaming meanie… it keeps the LED at around 44 degrees C. Not too shabby sloughing off over 150 watts of heat.
Now to add a big honkin’ reflector and a dimmer/monitor/etc processor.
Good luck with the reflector. When its done, make sure you use the same eye protection that the folks were using to witness the recent total eclipse in northern Australia before powering it up
I’m not sure that I like that copper heatsink that I am using. It is nice and compact and works VERY well, but the fins are short and closely spaced. That requires high pressure air to get in there. The fan on it is a screamer and is recessed into the fins. I would like to build the engine up with a single fan that can provide air to both the LED and the driver.
I am planing on building a small board that fits on the back of the driver. It will have the ACS712 current sensor and an AVR (ATMEGA328?) that controls everything. It would have a FET for switching power to the driver, one for PWMing the fan, and one for PWMing the LED. Parasitic drain on the battery should be around 20 uA. Dimming via a button or pot. It would also monitor the battery, etc.
And something tells me this thing will make an awesome puke light J)
When I was setting up the constant current mod, I had the current level set at around 2A. That is below the minimum level that the circuit wants to work at. The thing started flickering some. I went to crank up the drive level, but turned the pot the wrong way. Then it REALLY started flickering. The effect was rather awesome, even though it was only doing 5000 lumens at the time and the LED was shining into my sphere.
I kludged up an external PWM dimmer onto the constant current driver… it failed miserably. Any dimming caused the LED to go into puke-flicker mode. Turns out that the stock program in the dimmer is PWMing at 100 Hz… way too slow to maintain a stable output. The constant current driver has a 1000 uF output cap, which 5A of current significantly drains between 10 millisecond PWM pulses.
I need to reprogram that dimmer chip for something like 10 kHz PWM…
I think that spec is only for an SST-90. Perhaps if you could get 15k lumens from an SST-90 sized emitter you’d be able to get that kind of throw, but the array is freaking huge. I expect closer to 100kcd, given that the bare emitter already gives off 15kcd.
I'm curious how it will perform with SST-90 reflector.