Modifying a 1W Single AA LED light

[jasonck08]

Ok so the otherday I picked up a really nice little UltraFire 1W AA LED light with a lanyard and case for less than $5. I would like to modify it to get 100+ lumens out of it.

I plan to use a Q5 with a 14mm base. If I wanted to run it off a single Ni-Hm AA, I would need a driver board that converts 1.2v to 3.6 and at 500mah+. Most of the driver boards I have seen that do that have many modes. I do not want a lot of modes, just 1, 2 or 3. Now, it might be a bit hard to find a good driverboard that will output at 500-600mah off a single AA.

Another option I had in mind is using a 14500 and direct driving the LED. Now if I did this, would I expect to get full output of 200 lumens+?

So what do you guys think? Should I go the AA + driver board rout? Or should I just use a 14500? Thanks!

 

[Marduke]

This looks like what you want
http://www.dealextreme.com/details.dx/sku.7302

 

[jasonck08]

I did look at that one, but It is actually a 16 mode board with 3 groups according to a guy who posted a review. And one of the reviewers also stated 2/3 did not work.

I'm totally fine with direct driving a Q5 with a 14500. Would it drive it hard at the full 1amp, for 200+ lumen output?

 

[Curly]

I used a 4735 from DX. Works good, and it will work with 14500. The 14500 produces a brighter light but 1 Nimh is surprisingly bright too.

 

[jasonck08]

I think I want to stay away from a driver board this time....

So am I correct to assume that a 14500 will power up a Q5 and put out 200 lumens?

 

[LEDninja]

Minimak 14500 DD SSC-P4 left, L0D-CE NiMH right.

Minimak 14500 DD SSC-P4 left, L1T v2.0 RB80 NiMH right.

Please remember a 500mA circuit board pulls almost 2A from the battery. Not many AAs can deliver that after the first few minutes.
For example here is Silverfox's tests on an Energizer 2300mAh.

Note it cannot produce 2A AND stay above 1.2V for more than a couple of minutes. After that the light will run at a lower output.
Not all batteries are that poor. For example here is the Eneloop test result.

The battery have no problem providing 2A at 1.2V for 1/2 the runtime and very close to that for the remainder.
So if you go for a super duper boost circuit make sure you also have super duper batteries.

 

[pinball]

hello,

i did a mod on a rc-g2 which turned out very nice
look here for specs:
http://www.candlepowerforums.com/vb/showthread.php?t=180962
post #15
hope this helps :twothumbs

 

[Gunner12]

This driver can be modded to a single mode. Solder the negative wire to the outer ring on the top side of the driver.

As for 14500s, it should give you 200 something lumen at the LED. But overheating might become a problem.

 

[VegasF6]

I think I want to stay away from a driver board this time....

So am I correct to assume that a 14500 will power up a Q5 and put out 200 lumens?

Is this by chance a UF C3 with case, the older P4 model? I wonder about acheiving 200 lumens from it, I think that would really be asking a lot. I would also worry about heat driving it that hard. The 14500, which is the same capacity as a 16340 pretty much is good for about 700mah. So, to pull 1 - 1.2 amps from the battery is really at the limits. You could always test a 14500 with an amc7155x3 and the emitter heatsinked on a large plate or computer heatsink and measure the current, or even direct drive with a protected cell only, but I don't think you would acheive the 200 lumens. Also, the newer C3's I have gotten have a different switch assembly, with a big metal lip that wouldn't allow me to use the longer 14500 protected batteries in place of a AA cell. I was very disapointed by that. I know you said you didn't want a driver board, but I think you will have to limit the current somehow, and I don't really consider the 7155 boards to be drivers. They are simply current limiters, no modes, no boost, buck or anything else, along the lines of a resistor.

As far as I know, there is no commercially availible light that gives 200 lumens from a single 14500, but then, I don't know of every light out there

 

[jasonck08]

Just so everyone knows, if I went the AA Ni-Hm route, I would be using enloops, so current draw of 2amps is not a problem at all.

I guess I might go with this driver then 3W/5W 20-Mode 800mah output from AA I'll get it and likely mod it to just do one mode on high. 600-800mah output at the led is great!

I'll probably pick up a few more of these nice little lights. I have no idea what the model of this light is, but it comes with an ultrafire case, and I picked it up locally (in Taiwan) for $5. This store had about 5 of them in non-oem packaging for a lot cheaper than normal. I have seen this light elswhere for $12 in stores.

 

[jasonck08]

I opened up the light, and it has no heatsink what so ever. So I was thinking I could buy a small round piece of copper (like a pill) and then use thermal paste and glue it to the body of the light. I don't think the copper could be much bigger than 7-8mm long and 16mm wide.

Do you think this would be enough to cool down a Q5 at 600-800mah?

 

[Gunner12]

Depends on how thick it is.

I remember someone using a correctly sized pipe part as a heatsink and pill for a mod, so maybe you can find one that works.

 

[jasonck08]

I think it will work just fine. On another light I have a Q5 on a thin aluminum plate that is connected to the body of the light. No problems with it, and I have run it for over 30 minutes at a time.

I'm thinking of making two of these lights. One 14500 direct drive with a larger heatsink, and one AA with driver with a smaller heatsink. Both will use Q5's.

 

[mikeh]

I'm totally fine with direct driving a Q5 with a 14500. Would it drive it hard at the full 1amp, for 200+ lumen output?

That depends on a few things.
The Vf of crees can vary a lot, so one LED may draw far more than another, even from the same bin.
If you buy a bunch of Crees, you can test them and choose a low Vf one for high power with direct drive. Or if heat is a problem, use a higher Vf LED for less current.

 

[jasonck08]

What would be an average "Vf" for a Q5?

What would that be in terms of current draw (mah) and output (lumens).?

Even if the average Q5 will put out 150 lumens, direct driven... I'm fine with that...

----------------

Also, I bought a cheap 3W light with a driver. I was thinking about just attaching a cree drictly to the light. And using the existing driver. Would this be ok?

 

[mikeh]

What would be an average "Vf" for a Q5?

What would that be in terms of current draw (mah) and output (lumens).?

Even if the average Q5 will put out 150 lumens, direct driven... I'm fine with that...

"average" is misleading, as a small change in Vf can mean a huge change in current on direct drive, if the battery has a low Ri.
See the datasheet for "typical" values for that bin. I think they give it for 350mA and 1A.
And of course, Vf increases with current. Its affected by temperature too.
You will get your 150 lumens, and then some, from a fresh battery, but that will drop as the battery drains. More consistent results will come from a low Vf part, plus a series resistor.
But be careful you don't kill the Cree. You need to measure it.

Also, I bought a cheap 3W light with a driver. I was thinking about just attaching a cree drictly to the light. And using the existing driver. Would this be ok?

Probably, if thats a 3W single LED, and has capacitors. But I'd check the current.