Quad Cree XR-E Q5 Driver Selection help... Complete, Thanks!!

Aircraft800 · Oct 18, 2007

Hey Guys,

Do you have a minute to help a LED nOOb?

I need a driver to run:

(4) Cree XR-E Q5/WC LED emitters at 3.7v and 1000 mA

using 2 (or 3 if needed) 25500 Rechargeable Lithium Battery (3.6V 5000mAh).

It would be NICE to have Low Battery warning since I'm using Li-Ion's.

I'd like to pack it all in a 2C or 3C Mag host and a Download adjustable heat-sync.

Thanks for the help!

Nereus · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

How about Sandwich Shoppe's Shark step-up converter? You can find the specs here. Shark does not have low battery warning, but if you use protected li-ion cells you do not need it because the internal circuitry in each li-ion cell prevents over discharge.

-N

DonShock · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

I'll second the Shark recommendation. I use it for almost all my multi-led mods. And two li-ion cells should be sufficient to drive four Q5s.

tino_ale · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

MaxFlex would also be possible, but input current would be a little high if using only 2 cells. Then you have a multiple levels lights, assuming you can modify the stock switch into a momentary one (not difficult to do)

beetleguise · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

NU B as well to LEDs.
I am planning to do the same, but would like to drive the Cree XRE Q5's has hard as I can without damaging them. The shark only goes to 980 ma, is this the ideal current? Also, the max input of the shark is 4a, if I were running 4 crees at 980 ma, would this be a problem for the shark? I am not sure of the efficiency of this driver and this may overload it???

beetleguise · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

I just read a previous post about the shark. Here was some great info!

dat2zip said:
The Shark has both a voltage feedback and current feedback internally. The regulator can be thought of as a voltage regulator with current limiting.

With J1 open (default) the voltage set point is 11.5V. With J1 installed the voltage output is changed to ~22V.

If you are driving LEDs, jumper J1. This provides open circuit or no load protection.

Yes, it's both. Just like a power supply you can set the voltage and current limit seperately.

If voltage and current regulator is still confusing you. Simply jumper J1 for LED driver applications and the Shark will be a constant current regulator with open circuit protection of ~22V and the trim pot sets the LED current.

Any voltage regulator is "safe" since it will regulate to a given voltage. For the Shark it will regulate to 11.5V or 22V with no load depending on whether J1 is jumpered or not.

The trim pot feeds the control pin. If you remove the trim pot you can hook up a microprocesor to control this pin.

If you know how to program a microprocessor you should have no problems creating a proto board using the Atmel Attiny or the microchip microprocessors to create a user interface to control the Shark. I leave that up the reader to determine.

I'm planning to offer a small microprocessor board as a bolt on addition, but, it's taken a back seat to the rest of projects I have.

A general rule of thumb to use the Shark.

1) Determine the number of LEDs you want to drive in series. Example: 4 Lux3s.

2) Determine the series voltage of the LEDs at the desired current. Example: 1A which means ~4V/LED and 4LEDs = 4 * 4V = 16V (approximately)

3) Determine the operating and min battery voltages using the total Vf output. Operating is > 1/2 output and min is approximately 1/3 Vout.

Operating should be greater than 1/2 of 16 Volts or a fresh battery pack should be 8+ volts.

At end of battery life your battery voltage should not drop below ~ 1/3 Vout or 1/3 of 16 = 5.3V

In this example a 9V stack of AAs batteries or a 12V stack of AA batteries would be fine for this example. What won't work is 2AAs, 4AAs since the current demand will approach the limit of the regulator.

Example 2:

Three low Vf LuxV. say you have 3 LuxVs with Vf of approximately 7V @ 700mA. That's 21V which is below the 22V open circuit protection (with J1 jumpered).

1/2 21V is 10.5V and 1/3 21 is 7V.

A 12V battery pack would suffice for this application. A 9V battery pack would be marginal for this application.

Wayne

beetleguise · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

I just found an answer to my question regarding the current input/output limits of the shark:
quote=dat2zip;1683538]Your input/output ratio is 3.6V:~14V or ~1:3.9

Simplified calculation is for the current knowing the Vin/Vout ratio and apply the same for the current. 14V@1A equal 3.9 X 1A to get the input Current = 3.9A. That's too much for the Shark. 14V @ 0.7 = 0.7 * 3.9 = 2.73A. That's possibly OK since we did not factor in the efficiency of the converter so input current will be higher than 2.73A by another 15% or so which will go over 3A again, but, not by much. So, 700mA is around the limit for the Shark in this configuration.

It really doesn't matter if you crank it all the way up to 1A. If the converter can't deliver 1A it will deliver the max it can deliver. If that's OK with you, run it to the hilt. If you want constant light for longer duration turn it down a bit.

-Wayne[/quote]
So, if I want to max out my 4 crees, this would not be the best driver for me. What is the max current for a cree XRE q5 to run without damage? I really want to push the brightness in this mod without having it destroy itself!
:anyone:

ledaholic · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

I have 2 2D mags with 5 Cree's running on a shark turned up to max with 8 AA Nimh (9.6v) with no problems. The Maxflex driver has a low voltage indicator option and several different UI's built in. Either will work well.

Aircraft800 · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

ledaholic said:
The Maxflex driver has a low voltage indicator option and several different UI's built in....

I LIKE that option, just not sure of the complexity of setting up this driver, there is a lot of programming options, and I'd have to do something about the switch "The switch needs to be of a momentary action push to close type, i.e. normally open contacts", I haven't seen this mod yet, I'm sure there is a tutorial.

http://www.taskled.com/leds/maxflex_ui.pdf

saabluster · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

There is a heapin helpin of Texas folk in this thread.:wave:

ledaholic · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

Aircraft800 said:
I LIKE that option, just not sure of the complexity of setting up this driver, there is a lot of programming options, and I'd have to do something about the switch "The switch needs to be of a momentary action push to close type, i.e. normally open contacts", I haven't seen this mod yet, I'm sure there is a tutorial.

http://www.taskled.com/leds/maxflex_ui.pdf

On the other hand, there is a board (Remora) also available from the shoppe that solders to the Shark that will give you 3 levels output.

The Mag switch works just like a ball point pen, you just cut off the plastic tabs and presto, a momentary switch.

Bob

Aircraft800 · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

saabluster said:
There is a heapin helpin of Texas folk in this thread.:wave:

Come over to my house and help me build this thing!! :grin2:

Thanks Bob,

You are really helping me find the correct stuff, If I had to just go there without help, I'd never know what to look for.

Keep the suggestions coming, it's good therapy!!

http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=988

....

kurni · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

I'm a total noob myself; but the folks here have been very helpful. I prefer buck over boost because:

Theoretically, higher current = higher resistance.
To compensate the low voltage, boost circuit has to draw higher current.
It's my first mod so I don't want to worry about the resistance in the spring / cables / switch / battery joints or whatever.
Alks has significantly less capacity when high-current draw is applied; I am guessing that NiMH is similar although I don't know about LiIon.
I have heard a few folks here testified that 1 LED @ 1A is brighter than 3 LED @ 350A; I'm still confused about this as the theory says that the Lumen/Watt is less as the current increases.

My current project is 6D M@g mod; I want to use alks because I can just leave them for years; it's my backup LEC (Light Emitting Club). Alks are cheap with presumably less self discharge than rechargeables.

Depending on how my current mod goes (I'm still waiting for parts), my next mod might be 6 14500 > 2D to drive 5 LED using a buck circuit. I guess it would be crap runtime although hopefully blinding bright.

Here are some good info I found:

I hope that helps :thinking:

katsyonak · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

How about 5 CREEs?
I'd like to mod a mag with 5 CREE Q5 WC LEDs driven by the shark. I havn't decided on the current yet, it depends on how hot it will get and I was also thinking of adding an external pot, but I was wondering, how many batteries would be safe for the shark with 5 Q5s? would 2 AW "C" batteries be okay? Or maybe 4 Protected R123A? This is all very confusing

3rd_shift · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

Lotsa Texans in this one huh...

The stars at night are big and bright...
deep in the heart of Texas..

Oh wait, those are modded flashlights!

I kinda like the idea of a series driver, as it runs all the current through all the leds evenly.

There is a small penalty with efficiency from stepping up from 7.5 volts up to 14+ volts to all 4 leds though.
This had been my reason for staying with near direct drive instead.
But after seeing Donshock's lights, I then became a believer in driver circuits too.

ledaholic · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

3rd_shift said:
But after seeing Donshock's lights, I then became a believer in driver circuits too.

Donshock's lights are what started me building multi emitter lights. I got one of Don's 5 Q5 lights at the get together and have built one since. Both using 8AA to 2D. I have parts on order for another, a 3D using 3 18650's and a Shark/Remora. I just discovered I have an old 3C begging for 5 Q5's and 3 C protected Li-ion's!

Bob

kurni · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

katsyonak said:
How about 5 CREEs?
I'd like to mod a mag with 5 CREE Q5 WC LEDs driven by the shark. I havn't decided on the current yet, it depends on how hot it will get and I was also thinking of adding an external pot, but I was wondering, how many batteries would be safe for the shark with 5 Q5s? would 2 AW "C" batteries be okay?

I only know the theory: 5Q5 @ 1A 3.7v means 5*3.7*1 = 18.5 power needed. AW C can be drained @ 5A (assume 3.7v) so you have 2*3.7*5 = 37. Because 37 > 18.5 you theoretically can power 5Q5 BUT...

Assume 85% shark efficiency, you actually need 18.5/.85 = almost 22. To satisfy this, AW C batteries will be drawn at 22/(3.7*2) = almost 3A. This is within the limit of AW C (5A) and shark (4A) but this is where I am confused; I have heard that the spring at the end of M@g can provide a fair bit of resistance, so I am guessing that such problem might also exist in the switch, cables etc.

I have no field experience in modding; so I'm keeping it as simple as I can. I might even use BuckPuck even though I would love nFlex features.

katsyonak said:
Or maybe 4 Protected R123A? This is all very confusing

4 R123 would give you twice as much voltage than 2 C, so the amp draw would theoretically be 1.5A; better but personally I prefer 6 14500 in 2D mag to drive 5Q5.

I'm looking forward to my first mod: 6D M@g using alks, BuckPuck, & a heatsinked Q5/WH; still waiting for the parts though :mecry:

katsyonak · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

What current do you use with a 5 Q5 flashlight and how do you overcome the heat? How hot does it get?

katsyonak · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

Thanks kurni, that was helpfull

I have most of the parts and still waiting for the 5 Q5 WC CREEs, but I don't want to waste them nor the Shark making mistakes.

kurni · Oct 18, 2007

Re: Quad Cree XR-E Q5 Driver Selection help

katsyonak said:
What current do you use with a 5 Q5 flashlight and how do you overcome the heat? How hot does it get?

I hope I haven't drifted away from the thread; download appears to sell a nice heatsink, but I am rather concerned about the amount of surface contact with M@g body. H22A sells 1-LED heatsink that appears to have more surface contact. The sandwich Shoppe sells 3-or-4-LED heatsink that appears to also have more surface contact but no HAIII, which is useful for electrical insulation.

Use Arctic silver rather than ceramic to lubricate / glue the components. Arctic is meant to increase surface contact at the molecular level.

download said that 6D mag would become a hotrod in a few minutes if 5 LEDs are driven at 1A. Some people can fin M@g head to increase the heat-dissipating surface but I'm staying away from it at the moment due to the cost; besides, if dirt gets in between the fins it out be a pain.

PS: MaxFlex should be heatsinked if you're drawing more than 1A; to maintain efficiency MaxFlex should be powered at 2.2A or under. Shark on the other hand can go up to 4A, but I don't know why there is nothing about heatsink at shark spec page.

Quad Cree XR-E Q5 Driver Selection help... Complete, Thanks!!

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