The Bridgelux array requires around 30 volts to run. At 5 amps/150 watts in, it puts out over 16,000 lumens. Not many drivers are available to run it. So I build my own driver. It gets it’s own thread: An ultra high power direct drive LED driver
Powering the beast is a 6000 mAh 8S lipo battery pack (actually 2 4S Turnigy Nanotech packs in series). Those batteries can dump over 1000 amps. The driver is a direct drive driver. To control the maximum current that the LED can see, you have to charge the batteries to a certain voltage. 30.4 volts gives around 5 amps. Each 0.5V increase in voltage raises the current around an amp. If the battery voltage is too high, the driver starts backing off the PWM level to help protect the LED. Above another threshold, it won’t even turn on the LED. I’ve driven it at 10 amps… I might eventually go with a 9S LiFePO4 pack.
Edit: I did a better voltage vs current test with the assembled light. At the 5A drive level the emitter array puts out over 110 lumens/watt. At 7A it is around 95 lumens/watt (21,000 lumens):
29.5V - 3.6A - 105 watts
30.0V - 4.5A - 135 watts
30.5V - 5.4A - 165 watts
31.0V - 6.3A - 195 watts
31.5V - 7.0A - 220 watts
The emitter is bolted to the reflector/heatsink/pasta bowl with four M3 screws. Antec Formula 7 diamond thermal paste was used. I usually use my own diamond paste, but wanted to give the Antec stuff a try. Seems to work well.
Getting rid of all that heat needs some assistance. So there is a cooling fan mounted to the bowl. The driver controls the fan based upon the LED temperature. There is an LM35 temperature sensor epoxied to the LED “star” with silicon carbide filled epoxy. At around 80 watts in the fan does not come on (I guess that paint job is doing it’s job). At 160 watts in the fan is at full blow and after around 5 minutes the driver has to start backing off the LED drive level to keep the temperature within the programmed limits.
Here’s the fan tower. That plywood disk gets epoxied in to the flashlight body and supports the reflector. The fan is mounted on stainless steel standoffs to prevent back pressure from reducing the air flow. There are intake and exit holes drilled in the flashlight body. The temperature sensor wires and LED power wires feed though the bowl. Rubber grommets prevent chafing. The temperature sensor and power wires are kept apart so that those hugh current pules when the light is being PWMed don’t corrupt the temperature sensor readings.
Here’s the driver mounted in the tailcap: