Yep, that’s the problem. Nighttime hides when the big boys come out to play.
The 15,000 lumen device is wired to a bunch of instruments… not very portable.
I got in a couple of those 600 watt drivers (http://www.ebay.com/itm/DC-DC-600W-10-60V-to-12-80V-Boost-Converter-Step-up-Module-Power-Supply-/170893208817?pt=LH_DefaultDomain_0&hash=item27ca076cf1) They are about 3 times the volume of the 150 watt one. They don’t require any mods for constant current output. They come shipped from the factory set for 56V out and 2.5A (ymmv). It also has a fuse on the input so that if the output FET shorts your batteries won’t get all uppity and kill you.
I cranked the output voltage setting down to 33V (a little above the led array Vf) and fired it up. Voila lotsa light. Cranked the current up to 5A. Voila, mega freakin’ lotsa light. Efficiency is around 90%. The heatsink barely gets warm so it doesn’t need much in the way of airflow to keep it happy.
Next I tried it with the dimmer. It works a lot better, but below around 35% I get an occasional blip (maybe every couple of seconds) but no puke mode flicker. It is worse at 35 kHz PWM than at 120 Hz. I need to play some with different PWM rates and see how it behaves.
I may just not use PWM for dimming, but instead wire an external pot in place of the driver’s 100K current limit pot. I checked and 9.09K gives me 5A, 56K gives 2.5 A. I figure a 9K resistor in series with a 100K pot should be just about right.
By not having to PWM the LED, that frees up a pin on the micro and I can do all the monitoring and thermal/battery protection with a ATTINY85 (or TINY13 for that matter). Using a micro that has more pins/ADC channels would let me independently monitor each cell in the battery pack, though.
Before adding an external current limit pot to the driver, I figured it would be a good idea to try running the one on the board through it’s range. It won’t go below 1.25A.
Around the 2.5A area it gets a bit woogedy. Just touching the pot with a screwdriver or even touching the (isolated) heat sink causes the current to shift around 200 mA. Above or below 2.5A and it is OK.
Dim it, damn it! Who’d a thought dimming a 150 watt LED would be such a pain… I really don’t want to have to design my own boost driver just to get a decent dim.
I took the 100K current limit pot off the board of one of the drivers and replaced it with an external 500K pot. That lets it dim down to 600 mA (about 10%). For the best dimming profile the pot should be an audio taper pot.
There is the same glitch in the current output around 2.5 amps. As you increase the current from 2.5A to 3A, the current drops back down to 2.5A and then starts rising again as you turn the pot some more. This issue looks like it is inherent to the driver design.
There are a couple of issues with using the a manual current adjust pot to do the dimming instead of PWM. First is a potential color temperature shift with LED current. This does not seem to be a problem with the Bridgelux arrays.
Second is the fact that the control processor can’t do things like backing off the LED drive if the battery voltage starts falling or the LED starts overheating… you can only turn the light off. There are some digitally controlled pots out there that might be usable.
We are all still following this even though were not responding. Keep it up.
Darn, I thought I was yammering to myself and those pesky voices in my head…
Yes we are following, it's just not many understand all this stuff so well I guess. But this is interesting and there is always something new to learn, so I'm
+1 with MRsDNF, keep it up! 
Wondering would you mind sharing a link to that C9000 Bridgelux array?
Digikey and Newark sell them. They are now less than $60.
I am also follewing your project. Keep it up. Especially interested in to PMW the LED with an Attiny AVR.
I use this board for a lot of things. I’ve modified the firmware for many times. Also modified it to handle MUCH larger loads and voltages.
Posting the link to NewarK:
Dig-Key even cheaper:
http://www.digikey.com/product-search/en?x=20&y=13&lang=en&site=us&KeyWords=Bridgelux+C9000
Thanks for the link. I will build one for testing.
Wow, that’s awesome. How many 18650’s to power it, seven? 
With 12V in it draws around 15 amps. Power can be provided by a 4S - 8S LiPo pack or a 4S A123 20 Ah LiFePO4 pack or a lead acid battery. An pack made of IMR cells or a power tool pack would also work fine. The input voltage needs to be less than around 30V to work with the DC-DC converters that I have been playing with. My 180,000 and 540,000 lumen arrays used a custom buck converter that was driven from dual-redundant 16S A123 packs when in battery backup mode.
I was going to use the A123 cells, but those may not be readily available in the near future.
That’s Awesome, both as a stationary light or a cordless searchlight
[quote=texaspyro My 180,000 and 540,000 lumen arrays [/quote]
WHAT!? 
Have you showcased these here? Links pics? wow!
I’m running a 30E4000 array (‘E’ for 80cri) in a retrofitted floor lamp. Bridgelux claims 4725lm at 2.1A; I’m driving at 2.5A so the Flux-Current chart on the datasheet suggests it’s running around 5600lm. Mounted to a salvaged CPU heatsink and cooled by a small, undervolted fan. A custom pyramid base was constructed to house the power supply and provide stability.
Overall it works pretty well. Light quality is better than the CFLs it replaced; it’s comparable to halogen but it has an slight pink tinge if you do an A-B comparison. I’m curious to know what the 90cri array output looks like.
Kudos to texaspyro for turning me onto Bridgelux arrays last year.
Next project will be an outdoor floodlights based on a couple C9000 arrays.
Bridgelux has a new Decora line… with CRI’s up to 98! Not sure where to get them though.