Guru

[degarb]

Are there any guru's here willing to take on pinhead question for modifications of most lamps?

I got a 3 watt Dorcy 65 lumen and think a Souel p4 will be a snap to solder in.

1. Is it?
2. Where can I buy a cheap star replacement and get it quick?
3. Can 3 AAA drive it or will it cook it? Only reason I ask is that I wired directly into the boar on one of my brinkmans where the switch was shot, converting it to 3 AA.
4. Also, I think I will try a 4 AA with variable resistor. Will this make it more efficient and what type to get?

3 AAA 3 watt led is just plain brain dead.

 

[Gunner12]

Cheap and fast, well, those don't usually go well together. Is this a headlamp or a flashlight? If it's a flashlight, would it be easier to buy a prebuilt one?

Cheap, look at Dealextreme's Seoul Star or Kaidomain's Seoul Star.

3AAA would work fine since they don't have a lot of capacity.

You could also fit a rechargeable 18500 Li-ion battery(go with protected batteries) in there with a driver(like this one) for more output then the AAA batteries can provide.

 

[degarb]

The souel star looks like the 3 watt lux star, except differing + and -. Does it matter which + or - you solder into.

Now, the cree looks more different. So I am guessing Souel easier.

I will need to further research the lions. Cost, charge time, cycles. I guess that if you could do 4 parallel 14500 in the AA form, wire into the existing 3 aaa positives and negatives, you would get 4.5 times the juice; and since 3 watt suck 3 times the 1 watt juice, we could get up to 4 hours of light at 3 watts with 4 aa sized lions. (With triple that life at 1 watt, but would need variable focusing lenses for differing wattage) Then things would come down to cost.


Yes, the Dorcy is a plastic headlamp. I use headlamps and starting to supplement with wrist lights made from $11 1 watt nichia flashlights, velcro, elastic, and hotglue. I am leaning toward only plastic since I find metal light less modifiable, and too heavy for a headholder to be comfortable (reason I probably wont buy the fenix l2d, even if cost drops).

 

[Gunner12]

There is probably little to no heatsinking in that headlamp so I'd solve that problem first before moving on to anything else. There is a reason why many good High Power LED lights are made of metal. It is there to transfer the heat from the LED to the outside so the LED does not overheat and burn itself out and not only because a metal light feels good.

A Cree Q5, one of the brightest single die LED as of today, is producing less the 1 watt of light energy at 3 watts. The rest of the energy comes out as heat.

A Li-ion battery is 4.2V off the charger and has about the same capacity as a normal 1.2v rechargeable battery. At 4.2V, the LED will be drawing way over 2 amps and has a good chance of burning itself out or turning very blue(Sign of overheating). A 14500 battery will always be AA sized, it is 14mm in diameter, 50 mm in length and cylindrical shaped.

As long as you solder the + output wire to the + output contact and the - wire to the - contact, you should be fine, but there have been example of DX Seoul Stars with a reversed LED(the + and - have been swapped, someone messed up) you might want to be careful.

It also seems that you like a Narrower beam, then how would a Cree Q5 with this optic(8 degree beam) on a good heatsink driven by 4AA through this driver suit you(there are also many multimode drivers like this one)? Even narrower? Then you would need an aspheric lens.

You can have a lighter heatsink, that would mean a smaller CPU style heatsink with a fan so the heat is removes fast enough.

The Newer LEDs are twice as efficient as the Luxeon I, III, V and K2s. So just swapping the Luxeon III(probably a Luxeon III) with an Seoul P4 U bin LED will give you double the output.

P.S. It's spelled Seoul like the city, not Souel.

Edit: I guess you need the light for painting. Even now, the only thing that compares to a 2000 W lamp is 260 Cree Q5s each driven at 1 amp.

 

[degarb]

Thanks gunner! I didn't see any heat sink in the dorcy.

Do I need a new driver if I solder in a the Cree? And what ideas for heat sinking specifically? (I could remove the window, or are there metal reflectors?

Also, will better heat sinking improve battery life?

 

[Gunner12]

Heatsinking might improve battery life but not by much. Most of the heat from the LED comes out the back so a meta reflector won't do much if it is not touching the LED. It's mainly to prevent the LED from overheating and improves reliability.

I would suggest a fitting CPU heatsink.

If you will be running the light with 4 batteries, you would need a driver.

Humm, 12 hours out of 4 AA batteries. Presuming 2500 mAh batteries at 1.2v.

1.2v * 2.5 mAh * 4 = 12 watts power, so about 1 watt draw from the driver.

Presuming 80% driver efficiency and 3.3v LED Vf.

0.8 watt / 3.3v = about 240 mA to the LED, which is around 75 lumen at the LED for a Cree Q5. With the above optic and no window, around 60 something lumen out the front.

Closest driver to that current that I know of is the Son Of Buck 400. Runtime would be around 7 hours with 4 2500 mAh 1.2v AA batteries.

How about a cable to a battery pack on your belt, then you can use bigger batteries and longer runtime. Or taking a preexisting LED light and wiring it to work as a headlamp?

Here's my idea:

A Cree Q5 with this optic(single pack) driven by this driver and powered by 1-3 Li-ion 18650 3.7v rechargeable batteries(18mm in diameter, 65mm long, usually 2-2.2 mAh, yes, they are a bit big) in parallel with the head of this light as the headlamp part (or modify the Dorcy headlamp).

With 1 battery, around 1.5 hour on high(200+ lumen out the front), 4 hours on medium(100+ lumen), and 18 hours on low(30 something lumen).
With 2 batteries, around 3.5 hours on high, 9 hours on medium and 36 hours on low same output as above.
With 3 batteries, around 5 hours on high, 13 hours on medium, 50+ hours on low, same output as above.

Total cost? around $18 for minimal price(one Cree Q5, one optic, one driver, modified Dorcy, presuming you already have a 18650 battery, a right sized heatsink, and thermal paste/epoxy).

For everything(3 AW 18650 batteries, a charger, a Cree Q5, Driver, one optic, the above light, a driver) around $110.

There are cheaper 18650 batteries and cheaper chargers.

 

[degarb]

Thanks again, you give me more to study.

I can't quite visualize a cpu heat sink in heat lamp.

Also, would a pot, variable resistor, after battery pack, help battery life?

 

[Gunner12]

It's this light right? I'm guessing that your Dorcy has about 42 lumen out the front(65 lumen at the LED * 65% light transmittance of the reflector and the window = about 42 lumen).

A chunk of metal that fits will also work as a heatsink. I said a CPU style heatsink because it provides more surface area and can dissipate heat faster, but this won't be much help if the heatsink is enclosed.

Depends how you make it. If you put a variable resistor between the battery pack you could more finely tune the output you want, but since it is a resistor, it will suck some energy. If you are using a variable resistor, it would be better to use a single mode driver and not a multimode one.

With the Cree Q5, it is possible to get 45 lumen out the front for 9-10 hours(Probably a bit more, I usually round down my calculations) with 1 18650 battery.

 

[degarb]

Yes, this is the Dorcy lamp.


Radio shack has a 25 ohm pot for $3. What pot would be considered ideal?

 

[degarb]

At mall yesterday, saw a 3 aaa headlamp with no specs at Brookstone, http://shopping.msn.com/Prices/shp/?itemId=435860264. (Geez, how hard is it for a label of lumen, beam throw, and battery life?). Interestingly, the lens/window was solid acrylic except center, which tunneled to the led to expose it to air.

 

[Gunner12]

I don't know which pot would be ideal, someone else would have to chime in.

That headlamp sounds like it has an optic, which usually has a empty "pillar" where the LED is bot the pillar doesn't extend to the surface.

Most of the Lumen rating aren't accurate, some have maximum at the LED lumens(much lower than actual out the front), some have out the front lumens and so on. Battery life depend a lot on the batteries used and some manufacturers can be lazy. They could put any throw figure on the light and get away with it. A 1 lumen light could probably throw a mile, but it wound be of any help.

I would stick a fitting heatsink in the Dorcy, put a Cree on that heatsink with the optic I liked to above, driven by the above driver, and have a wire to a 3.6v battery pack(6 amp hour an up) attached to the back of the strap or on to your belt or another attachment point. Total about $18 if you want to make your own battery holder and already have batteries, if not, then 4 cheaper 18560 batteries costs about $18 and 2 chargers costs about $13.

But that's just my thought.

My question is:
How much light for how long?

 

[degarb]

How long? Well, ideal world would be 13 hours (longer than most 10 to 12 hour days I like to work). So half of 11 (average) is 5.5 hours would really be the minimum for a quick swap. (Where does one buy rechargeable LI-ONs locally? So, when batts go bad, you don't have dead lamps until six week later after shipping?)

So, any way to avoid needing a new driver, and just Solder in the Cree xr-e to the old headlamp? Also, I was doing ton of tests, and find the lux on the 1 watt Brinkman greater than the 3 watt Dorcy (I vow to never buy Dorcy again. I own at least 6 of these 1 watt luxeon Brinkmans.) So, I will likely not use the 3 watt Dorcy until I modify with a Cree--too much juice and too little detail illumination. I see also in my Brinkmans, soldering a Cree star to its heat sink, should fit perfectly. But would the Brinkman need a driver too?

Some update: I couldn't help myself; I bought an Energizer Swivel flash light at Lowes for $39, with Luxeon Rebel 80 lumen rating. Wow! Perfect optics reflector for me. And the light, even on low, blows anything I got away. Not like night v. day, but more like putting on glasses with vision you previously thought good. Shine that Rebel on a wall at 12 feet, and it is like being right there at that spot with 500 watt light looking at it. Good corona too. Only downside is my attempts at making it a practical, usable head lamp have failed (industrail velcro and elastic), and it barely makes a practical wrist lamp as it requires several straps and not quite the angle ideal to use a paint bucket and see surface at same time (left hand light). A bit too bulky all way around. (Will be great when they put this bulb into the sportman model.) Not sure if I rechargeable swap time going to be in the 5 hour range yet, on the kick butt low setting. The 3 aa Alkaline batteries died at hour three on low setting.

This light tells me that sooner I can convert a few headlamps to Cree, the better.

 

[degarb]

Also, I have hot glued on one new 4 AA pack and 25 Ohm pot to center strap of one Brinkman 1 watt and the 3 watt Dorcy (3 AAA source is a joke even on a 1 watt). Interestingly, on the 3 watt lux 3, it seems to have more a dimming effect than on the 1 watt.

I do see more light with 4 AA, than with one dummy in the pack. So I guess I could just run this at the 60 degree off max setting, and manage not to burn out light? I don't see a drop if volt with the pot, so guessing amp drop. (I think I need to buy battery for the tester, since it isn't registering amps, and volt reading is 5.3 volt at 4 AA NiMH, which doesn't sound right.)

Since working outside now and only using the lights with pots, from 4:30 pm to 8-11 (jumping between lights too..then bad cells, probably from my 15 minute quick chargers), I haven't yet fully tested battery life of my newest mods and purchases. (The unmodified 3watt 3AAA was unacceptable even on low.)

[I learned also that the 4 AA is significantly heavier than the 3 AA pack mod. I solve the comfort issue by padding back of pack that touches my head. Lions would solve any weight issues. Also, No experience with any belt solution; imagine it would take very creative engineer to do it elegantly, and probably wiring would out-smart any of my workers...That is the great thing about my Garrities, 3 AA lux 1 (8led) http://www.garritylites.com/page567.html# , simple and more comfortable design than my home modified Brinkmans. But won't be happy until I have a next generation led, with similar to my Garrity's 9-11 hr runtime on 3 AA.]

 

[Gunner12]

The Energizer Hardcase light actually has a Cree XR-E LED in it, not a Rebel(Probably a P2 bin, putting in a Q5 would bump the output up about 50%)

Keep in mind that a fully charged NiMh battery is usually around the 1.4v range.

3 NiMh Batteries have around the same power as a single 18650 battery(high capacity NiMh batteries would have more power).

I don't think your 3 AAA lights even have a real driver. Probably just a resistor and something for modes. A driver aren't that hard to install either, you just have to make two more soldering points. The + wire from the battery pack goes to the center round + contact pad on the bottom of the driver, and the - wires goes to the - outer ring on the bottom of the driver. The the + wore from the driver goes to the + contact on the LED and the - wire from the driver goes to the - contact on the LED.

A battery pack just holds the batteries in a container with the batteries connected and a wire leading the power from the battery to the light. Simple in concept. The wire can go anywhere as long as it connects the batteries to the light.

I don't think there are any pre built Headlamps that fit your description.

You could use this light's head and wire a 3 AA or 4AA in parallel battery pack and that should give you at least 7 hours runtime on high with 3 batteries and at least 9 hours runtime with 4 AA batteries(figures are with 2 amp hour 1.2v NiMh battery, 2.5 amp hour batteries would give you about 9 hours on high for 3 batteries and 12 hours on high for 4 batteries) Total output will be similar to the Energizer light you have(same or a bit more) but the hotspot won't be as powerful.

Light's head, look on the bottom where the battery meets the circuit board, wire a wire to the center + contact and a wire to the - contact ring. then wire those batteries to a switch(the switch of the light?) and to a 1.2-3v 8 amp hour or up battery pack.

Li-ion batteries make up a laptop's battery pack but they are different sizes(usually 18650s) and unprotected(higher chance of overdischarging and overcharging the battery). Someone has used these DX batteries to make a Laptop battery pack.

 

[ljsmith]

I have this exact headlamp. I put a Cree Q5 in it. I just removed the old star and soldered the new one in. The headelamp was bright, but a bit ringy with the existing reflector. Then after about 1 hours use the reflector started to melt (its plastic) and it shorted out the led.

 

[Gunner12]

That is why there should be a heatsink, so the heat doesn't concentrate on one place and end up breaking something.

But heatsinks can be heavy. Either: drive the LED at a lower current, or get a finned heatsink(more surface area).

I hope you can still get the Q5 out without destroying it.

 

[degarb]

LJSMITH, I take it you didn't put in a controller?

For me, 65 lumens would be plenty. I am guessing I would use a variable resistor, plus some fixed resistor at some ohm (but what--5 or 10ohm?), to dim down to proper level. Now I am wondering how I might make a heat sink in this lamp. (Brinkman headlamps have heat sink. Perhaps, a quarter. Where to get thermal paste? Also, perhaps a hole drilled into lamp to let out heat.

Now, could a controller be put near battery pack, so as ensure current lamp compatibility? Also, I read that a hyperstrobing of the led, beyond human perception (>50 hertz), could be a trick some contollers might use to double battery life. Are there controllers that do this on market? So, in theory, an ideal headlamp would have 4x current luxeon efficiency, and so, 3 AA (9.54 watt hour) would offer 19 hours of life at 80 lumens, and double that at 40 lumens--with Cree and superstrobing controller.

Another question, Gunner, if I bought a Fenix l2d rebel, would it be more efficient than a Cree? Would the Cree be better for painting, spectrum wise--as in truer white?

 

[Gunner12]

The Rebel LED has a better color rendering but the Cree usually has the whiter tint(the Rebels are usually a bit yellow).

Putting a driver does nothing about heat. The LED can still overheat(and melt a plastic reflector, burn itself out...) and the driver it self has inefficiencies so the driver would also produce heat. There aren't may drivers with temperature sensors that dim the LED when the temperature gets too high. Either way, it's best to have a heatsink. A quarter might not be enough. I would use something like a nut that will fit in the light. Thermal paste(Thermal epoxy would be better IMO) can be found at a computer store and online.

Strobing the LED very quickly(AKA PWM) is another way of dimming the light(It also keeps the tint, LEDs shift tint when driven at different levels, some shift more then others) so it does not affect efficiency. Halving the drive current would give you a more efficient LED and more light(LEDs get more efficient at lower drive currents).

A Cree Q5 produces about 63 lumens(numbers from here) when driven at 200 mA. Vf is around 3.1v. Presuming 90% driver efficiency since battery voltage(in series) is close to the Vf of the LED.

200 mA * 3.1v = 0.62 watt
0.62 / 90% driver efficiency = about 0.69 watt
9.54 watt / 0.69 = about 13.8 hour runtime

Presume no driver in inefficiencies:

9.52 watt / 0.62 watt = about 15.3 hour runtime.

With the current reflector and window, that would be around 41 lumen out the front.

Is the Rebel more efficient then the Cree, well, that depends on what bins you are talking about. The Rebel 100 is one of the most efficient high power LEDs out now but the Cree XR-E Q5 has more overall output(not much though, the R2s have even more output).

 

[degarb]

So, you are saying p2 bin is %65 as efficient at a q5, while Lux I is %50. This would explain why I am unimpressed with battery life of the Energizer Hard Case lights.

I added my 2 cents on that thread.