Help with a dead Cree C3 Flashlight.

Gunner12

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A white LED runs at a normal voltage of around 3.3-3.7v. It will light up at around 2.7v but 1.5 is too low for the LED to run. If you connect 2 AA batteries in series to the LED and it doesn't light(presuming the right polarity) then the LED is probably broken.

If the LED still works and the driver is broken, try this driver. It's pretty powerful(rechargeable AAs work best with this driver, only use 1 AA battery) but might require some trimming to fit and could be confusing to use at first(you can make it a single mode driver pretty easily though).
 
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richardcpf

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Ok good, here is a picture of the led and circuit board:

DSC00034.JPG

LED emitter: 14mm, board: 16mm.

I want to upgrade my light to Q5 and also upgrade my old board with a Multi-Mode or single mode that takes 1-2xAA batteries.

So far i found this:

14mm Q5
http://www.dealextreme.com/details.dx/sku.11023

Now I need a board that can output enough power to the Q5 LED and takes AA's. I measured the old board and it was 16mm diameter.

Since I'm new to the flashlight modding, Would be great to know which board is good for the Q5.

Thanks all for your responses!
 

freedom2000

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A white LED runs at a normal voltage of around 3.3-3.7v. It will light up at around 2.7v but 1.5 is too low for the LED to run. If you connect 2 AA patteries in series to the LED and it doesn't light(presuming the right polarity) then the LED is probably broken.

+1 Gunner12 :twothumbs

JP
 

freedom2000

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Ok good, here is a picture of the led and circuit board:


LED emitter: 14mm, board: 16mm.

I want to upgrade my light to Q5 and also upgrade my old board with a Multi-Mode or single mode that takes 1-2xAA batteries.



Now I need a board that can output enough power to the Q5 LED and takes AA's. I measured the old board and it was 16mm diameter.

Since I'm new to the flashlight modding, Would be great to know which board is good for the Q5.

Please read my previous post !

Check also your led under 3V (2xAA bats) I am pretty sure that you will not have to change it. AND a Cree Q5 is of course brighter than a cree P4. BUT a Cree P4 driven at 1A will be considerably much brighter than your UF original flashlight :twothumbs

And don't panic for the driver's diameter --> just sand it and the pill


JP
 

Gunner12

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As long as the voltage is enough, the LED will light. But if you want max power from an AA, I haven't seen any more powerful boost drivers(compared to the one I linked to above) for a 1.5v source that can fit in the C3(and still have space for the battery).

The board and the LED will make the total around $12, so maybe you just want to replace the board now and wait a few months for some newer bins to come out(more efficient and brighter).
 

freedom2000

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As I said above I still have the original 5 modes boost driver of the UF C3.
It is NOT very powerfull and reaches 800 mA max with 2AA.
It can be used with :
- 1AA
- 2AA
- 1 14500 liion

I can give it to you for 3$

JP
 

richardcpf

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freedom2000

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there is also this driver (4$) which is the only one able to pull 1A to the led from a single AA.
the drawbacks are :
- poor efficiency
- not really a constant current driver but a constant voltage one

they are tricky to install because componants on both faces and often with a "patch" to apply to correct a pcb problem (but easy to fix)

JP
 

freedom2000

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Good!

1. The LED works! Tried with 3V.
2. I think I'm getting these:

Q5
http://www.dealextreme.com/details.dx/sku.6190
1A board or 800mA board
http://www.dealextreme.com/details.dx/sku.11023
http://www.dealextreme.com/details.dx/sku.7880

Just two last question:
1. I can use the same on/off switch for the new board?
2. Would be run good with 2AA's?

I can do the soldering and trimming so it worth a try.

1) Don't change the switch

2) don't use the first driver with 1AA or 2AA (it is a linear driver totally inefficient if V bat < 3.5 +0.12 V --> the led will be dim.
The only solution to use it "properly" is to have 3 AA or 1AA and one Liion. This is wath I did to mod my UF C3

3) the 3rd one is good but only driving the led to 800 mA with 2AA. Beware also that its diam is NOT 16mmm despite of the false picture on DX site :whistle:

If I were you I wouldn't change the led with this config

the best choice would be for me this one
but you would have also to sand the pill and the driver a bit


JP
 
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richardcpf

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That means that i can use the old working LED with new AA driver?(DX SKU Plz)

or

Change to Q5 and use a 3.7v battery with the 1A driver?

Is there a good board that takes AA and delivers good output for the Q5? that would be perfect.

Your mod is cool...never seen li-ion and nimh working together.
 
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freedom2000

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That means that i can use the old working LED with new AA driver?(DX SKU Plz)

or

Change to Q5 and use a 3.7v battery with the 1A driver?

Don't change the Q5 yet...
Both Q5 and P4 will work with 14500 bat (Liion)

see my previous post for the "best " driver to give full juice to your led

What you could do immediatly is to supress all the electronics of your board, reassamble the led a use in "direct drive mode" with a 14500 bat
with NO regulation the led will be a little overdriven when bat is fully charged (4.2V) and will become soon under driven when bat will drop under 3.5V

(that's the reason why I have used AMC7135 board with a combo 1AA+1 Liion bats to drive my UF C3 (but please understand all the "safety advices" before doing the same thing on your light)
If you use the AMC7135 1A driver with a single Liion it WILL work safely BUT the full power will only be reached until Vbat will be above VF Led + drop out of the driver.
VF = 3.5V
drop out = 0.12V

thus you will get full power untill vbat > 3.72 V ... which is above the standard voltage of a Liion bat not fully charged... The driver will be usefull ONLY when the Liion is fully charged (10 to 15 min not more) and after your led will be direct driven and will dim progressively down...

JP
 
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Gunner12

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The Cree XR-E Q5 and thr Cree XR-E P4 have similar voltage needs, so the driver will work with both LEDs(but the Q5 would be around 30% brighter due to it being more efficient at making light).

The SKU 7880 will only with with 1 AA battery(or any source around 1.5v). With 2 batteries it can overheat and over drive the LED quite a bit(I've tried it with a CR123 battery). The other board you linked to won't boost the voltage from around 3v to the 3.5-3.7 that the LED needs, you would be able to run it on Li-ion batteries though. But unless you have the batteries already(14500 woth charger), it would require more money.

The switch you have in there will work.

The newer SKU 7880 is I think 17mm in diameter, so you'll have to sand it down.

Li-ion battery is around 3.7v normal and 4.2v full charged. A normal AA NiMh battery is around 1.2v normal and 1.4-1.5v fully charged.
 

freedom2000

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That means that i can use the old working LED with new AA driver?(DX SKU Plz)


Is there a good board that takes AA and delivers good output for the Q5? that would be perfect.

Your mod is cool...never seen li-ion and nimh working together.

Yes this one works well with 1AA (there is a potentiometer to fine tune the output voltage --> you can do what you want with this driver (even drive your led at 3A from a single 1AA)

BUT frankly speaking a 1AA config is NOT the best one that I have tried...
unless you use a single Liion bat (but needs a specific charger quite expensive...)
You can also add an extension tube (7$) to your flashlight and jump to the 2AA world (much brighter, much longer run time and even a nicer look and feel for the C3 (as says my wife)

Please : be aware that mixing chemistries (NiMh + Liion) can be dangerous if you don't master what you do... even if it works very well if you know your config

JP
 
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richardcpf

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My final choice was the SKU. 4735 3-pack for use with 2xAA and my old P4 LED. It was the only one i saw that was able to deliver good mA with 1 or 2 AA. I have the extension tube and I really want to use it.

It will be arriving the next week.

And do you know which is the max input for this item sku.7612? Im planing to get 2x14500 and a Q5 but i want to know if i can use both 3.7v batt at the same time.
 
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Gunner12

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The one main problem with the 4735 is that the wires aren't soldered on yet(sorry if I did not mention that), so you might destroy one the first time.

For the 7612, the max voltage I'll run it at is 6v.

For that voltage you might want a buck driver.
 

yekim

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I have 2 stainless C3's with 7880's in them and they are pretty impressive to behold. They appear brighter than either of my NDI's, at the very least on par. Brighter than my old P4 L2D CE. I know they are not driving their LED's to their maximum potential, but for a 1aa it is nice. I have a supposed R2 (from a DX drop in) in one and a supposed Q5 from a supposed Q5 C3 in the other.


Anyhow, good luck with the repairs and have fun. It is pretty addicting too.
 

freedom2000

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And do you know which is the max input for this item sku.7612? Im planing to get 2x14500 and a Q5 but i want to know if i can use both 3.7v batt at the same time.

it is 6V

Do not use it with two 14500 cells. When they are fully charged you can get 8.4V with 2 in serie... For sure your driver will :poof:

That's one of the reasons why I use a combo 1 NImh + 1 Liion witj this driver...

JP
 
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