Electronics, Lighting, & Gadgets - Ridiculous Brightness Desired

Howdy! I'm starting yet another lighting project, and I need some assistance. I though about posting this in Total Geekiness, but figured it would get lost in the shuffle. I have done some searching on here and elsewhere, but most posts are about flashlight mods, which isn't what I want. I know just enough about DIY LED to be dangerous. I built a 4-emitter Cree Q5 light last year in an aluminum housing, powered by a 14.4V Li-ion battery. It's ugly, but it works okay. The bFlex controller goes to direct drive all the time because the battery drops from an initial high of 16.1V down to its normal voltage. If I haven't charged it for a few days, it can get pretty wimpy. Heat has not been a problem, as I typically only use it when cycling, in temps of 8C or lower.

I want more light than I've got. Yes, I could overdrive MR16 halogens and get what I'm after, but I like the compact size and light weight of LED systems. I'm also fond of experimenting with cutting edge, so I'm looking at a Seoul P7. In fact, I want to run multiples. :D The specs for these emitters [AFAIK] are:
Vf = 3.6V - 4.2V
Drive current = 2.8A max
Watts = ~10W
Lumens = a bunch
Heat = tons

Some questions:
If I'm going to use, let's say, three of these in series plus a constant current supply (http://www.led-tech.de/en/LED-Controlling/Constant-Current-Power-Supply/PowerLine-Constant-Current-Power-Supply--2800mA,-30V--LT-1290_118_119.html), it would be 3.6 + 3.6 + 3.6 + 1 = 11.8V right?
Would there be any point in running them in parallel?
How do I calculate the battery discharge rate required?
How many Amp-hours would I need for ~2 hours of run time? 2.8A x 2h = 5.6Ah ???
Is it possible/reasonable to hook up a potentiometer or something between the power supply and the LED to dim it a bit? I wouldn't need as many steps as the bFlex, maybe 100%, 50%, 25% and off.

For heat sinking, I will have to apply a slab of aluminum to the back of the emitters, turn it off when it's above freezing and pray a little. :twitchy:

So, what are your thoughts? Is it doable or am I nuts?

-3.6+3.6+3.6+1 does indeed = 11.8V - This is your minimum input voltage.
-I would go in series, if you go in parallel you won't be able to cram all 2.8A down each and every one of their throats, at least not with the driver you have linked, it would have to have an even higher current output.
-Battery discharge rate for a LINEAR driver (which you have linked) is the same as the current you drive your LEDs with.
-5.6Ah is correct for a LINEAR driver
-You can't put a potentiometer in series with the LEDs but i suppose you could go in parallel to siphon off some of the current. It hurts my brain though because it would be a very inefficient way to dim the LEDs (you'd have less light and same power output). Oh, and the power flowing through the POT would be significant...The driver you have linked supports pulse-width modulation dimming, which adds complexity but results in more efficiently dimming the LEDs.

My thoughts, it is doable and you are nuts, but it sounds like a cool project. I urge you to consider a switching constant current regulator as that drives up the efficiency, although i did just have a quick boo online and the max current out i found was 1A for switching regulators. Unless you wanted to make your own (http://www.national.com/pf//LM/LM3401.html)

Jebus! I've spent the last while reading about PWM dimming, switching constant current regulators and the dictionary [so I can learn what those words mean]. The switching thingies look great and are super efficient [97%!], but seem to be highly unavailable. PWM looks really cool, but all I see are instructions made up of squiggly lines, as opposed to the actual product:
http://www.reuk.co.uk/OtherImages/ne555-pwm-dimmer-circuit.gif
Can I buy one of these pre-built, or do I get out the JB Weld and make my own?



Just kidding about the JB Weld. Even I know you use duct tape for circuit boards...

Hey pinkrobe (pinky?), I built a pwm controller a few years ago for one of my earlier diy efforts. I'm pretty sure you could adapt it to your needs. PM me if you would like to have it.

Hey pinkrobe (pinky?), I built a pwm controller a few years ago for one of my earlier diy efforts. I'm pretty sure you could adapt it to your needs. PM me if you would like to have it.

You have PM.

You might want to look at 3 x cree MC-E instead of the P7. More optics options. Wire in 2 parallel strings of 6die and drive off a maxflex (600mA per string) using existing battery. Should be over 2000lm.

You might want to look at 3 x cree MC-E instead of the P7. More optics options. Wire in 2 parallel strings of 6die and drive off a maxflex (600mA per string) using existing battery. Should be over 2000lm.
Pleas forgive my ignorance, but I don't understand the bit about "Wire in 2 parallel strings of 6die". Could you explain this in more detail?

Pleas forgive my ignorance, but I don't understand the bit about "Wire in 2 parallel strings of 6die". Could you explain this in more detail?

Each MC-E has 4 die that can be driven independently and wired up as you please.

Ah! Math! 3 emitters x 4 die = 12 total. Run 4+2 on one parallel line, and the rest on the other.

edit:
What is the advantage of running serial/parallel instead of all serial? Serial gives 3.5V x 3 + 1V = 11.5V @ 700 mA, which when using a buck should give just under 2000 lumen...
Why use the Maxflex [boost] instead of a buck, since the voltage out of the battery is at least 14.4V?

I get the feeling I'm missing something here...

These things take 700mA per die. The maxflex runs at 1200mA so over two strings thats 600mA each which is close to max rating of the LEDs, not much dimmer than the 700mA max. The LED voltage is 3.5*6 =21V which is under the 24V max of the maxflex. Its a good solution, lots of battery options too.

Serial you need to supply 2.8A which is a lot of current.

That makes a hell of a lot more sense now. I thought the MC-E was 3.5V per 4 die emitter. I kept wondering why everyone hadn't switched to these magical LEDs. :lol: Yes, MaxFlex makes a lot more sense now. The P7 seems to be difficult to find good drivers for, so this route is looking interesting...

I'm still taking all comments and opinions right now, so if you have another suggestion, I'd like to hear it...

Jebus! I've spent the last while reading about PWM dimming, switching constant current regulators and the dictionary [so I can learn what those words mean]. The switching thingies look great and are super efficient [97%!], but seem to be highly unavailable. PWM looks really cool, but all I see are instructions made up of squiggly lines, as opposed to the actual product:
http://www.reuk.co.uk/OtherImages/ne555-pwm-dimmer-circuit.gif
Can I buy one of these pre-built, or do I get out the JB Weld and make my own?



Just kidding about the JB Weld. Even I know you use duct tape for circuit boards...
Thats a motor control circuit, not for power LED's.
Deal extreme has LED driver boards. All you do is connect the LED to the output and the appropriate battery or batteries for the correct voltage range of the driver and switch for power input. The on/off switch also allows you to select between power output level and flashing modes.
http://www.dealextreme.com/products.dx/category.917
http://www1.dealextreme.com/productimages/sku_15880_4.jpg

Whoa... those MC-E's (pdf warning) (http://www.cree.com/products/pdf/XLampMC-E.pdf) are freaking cool... lot's of options with them for current/voltage. I gotta start hanging out on candle power forums. That is sooo my next upgrade.

So far the only source i found was LED Supply (http://www.ledsupply.com/creemce.php) rating at 370 lumens must be the K bin.

Cutter has plenty of Cree MCE product. (http://www.cutter.com.au/products.php?cat=47) They're in Australia, but last time I ordered from them they had everything to me in about 10 days. At least one of the available bins will put out 420 lumen @ 700mA. The more I think about it, the more I like the MCE solution. It will take some enhanced soldering skill on my part, but the flexibility of the design and being able to use something like a MaxFlex to drive it are big pluses. If I go with the P7, I would have trouble using my existing battery, and I'd have to use a PWM dimmer.

n4zou: I just posted up that diagram to illustrate my confusion over PWM. I have a somewhat better understanding now. Sort of.

Another question: If I go with the MCE solution, should I use the Boomerang reflectors (http://www.cutter.com.au/proddetail.php?prod=cut820&cat=47), or would the Carclo optics (http://www.cutter.com.au/proddetail.php?prod=cut818&cat=47)be a better choice. I would need to put a piece of plastic across the front of the light to keep water and gunk out in either case. The Boomerang claims up to 90% efficiency, while the other optics top out around 85%. I don't know how much it matters.

Pinkrobe I would hold off for a while, these things are just being released and I haven't seen any user beamshots. Polymer optics do a range that looks nice too.

Pinkrobe I would hold off for a while, these things are just being released and I haven't seen any user beamshots. Polymer optics do a range that looks nice too.

But I want it NOW! <stamps feet, pouts> :lol:

One would imagine that the MCE would have a similar pattern as the P7, which seems okay. I think that the optics would make a bigger difference in terms of the throw and spill. I was thinking of two soft spots plus one wide angle. I currently have two soft spots and two 25 degree floods, and I don't get tons of spill off of the floods, nor do I need it. My riding is all on-street with streetlights. I'm mostly looking for throw, but not a laser, hence the soft spots.

Looking at Candlepowerforums, a lot of the torch mods are based on reflectors as opposed to lenses. Is it just for better throw, or is there another explanation.

Yes, handheld torches you can always point exactly where you want so throw is key. For road lights 6-10 degrees is good. Elliptical optics are a good choice too, help you see around corners but don't waste light up and down. Maybe two 10degree and one 10x25.
See these (http://www.polymer-optics.co.uk/Cree%20MC-E%20Optics%20Range.pdf).

I was poking around on MTBR :eek: and it looks like 420+ warm white bins are on the way to Cutter. Also, there's a dearth of optics available for the MCE right now, a situation which should resolve itself shortly. One of the Cutter guys logs in to MTBR regularly and gives updates. I'll wait a few more weeks until the warmer bins show up and they get all of their optics in. They may even be able to pre-solder stars for 4s + 2s/2p, which would make my life soooo much easier. Woot!

If you want a shortcut to the ridiculous brightness thing, here's one option. :love:

I see a lightly used Hellfire listed for about $3500 . . . but I'm not sure if the price is for the light or the girl. :p

http://www.ruscelli.com/images/Flashlights/hellfire_01.jpg

Speaking of headlights...

As a typical guy, I can't help but admire many elements of that photo -- from the Hellfire light to everything it sadly obscures. :rolleyes:

:beer: