Need help making EDC (Thermal, driver) [help no longer needed]

[crosstalk]

I have just recently entered the world of bright flashlights, beginning with an LED Lenser I bought to help find our dog (at 2:00 am, a small light just doesn't help very much with finding him when he wanders away outdoors.)

While walking through Walgreens, I saw some small LED lights that, to most people, would be considered "bright." Of course, I bought one, thinking I would modify it.

They are made of metal (or at least seem to be, the electricity is actually conducted through the body.) They consist of three parts (the light head, a body tube, and the rear switch,) plus an inner battery container that takes three AAAs. It is roughly a 3.75" length, 1" diameter cylinder. Currently, there are 9 white LEDs in the head, giving it great flood (but a low lumen count.)

Looking on DigiKey, I found plenty of high-power LED modules, many (if no most) of which will fit in the head (which is just over 1" in diameter.) I also found 2000mah (not sure if the abbreviation's right -- milliamp-hour) NiMH batteries that are the same size as AAAs (but they're solder-tab.) I was not able to locate a maximum current capability for them. Of course, to drive most high-power LEDs, I would need a voltage boost converter. I could either build my own circuit or use an LED driver, but a driver may be a better idea. Unfortunately, it would have to be under an inch in diameter and about (this is a rough estimate) 3/4" in height (or fit in a cylinder that size.)

I know that with high-power LEDs, you need good thermal management. I can use the body as a heatsink, right? I believe it is aluminum. I am trying to get the highest brightness (highest luminous flux) possible, but it must be able to continuously run until the batteries are drained with my hand on the outside.

I have not been able to locate any good information on this -- so I came here for help. Can you please help me pick an LED and driver to build this flashlight with? I do not wish to buy a stock EDC light (I did recently see a 900 lumen one here, however,) and am doing this as a project in my electronics class (high school.)

Thank you for your help.

 

[crosstalk]

Re: Need help making EDC (Thermal, driver)

I guess I will just build a boost circuit that regulates for a constant current or voltage to drive the LED.

However, I am still not sure about the largest LED I can use in such a tiny case (well, it is an EDC.)

From my previous measurements, I roughly estimate that it has a 12 in^2 surface area.

Where can I find information about LEDs and heatsinks? Would the best guide to the heat generated be the difference between the electrical power and light output? In other words, should I use power in-power out to compare the different lights? I am probably not making a lot of sense here :o

I don't think I will find a suitable current regulator capable of boosting voltage, but I'll see. If not, I'll just use a boost voltage regulator with an adjustable output wired to a switch.

Can anyone give me a guide that explains the relation between heatsink size and the maximum safe power? I know I would have to assume the flashlight is maybe 50% of its actual size, as it is not shaped like a heatsink, so not all of it will heat up.

Thank you.

Edit:
I found some LED drivers on Digikey capable of doing what I need. I think I'll allow switching/dimming between bright and low modes, with thermal protection built in.

 

[Linger]

Re: Need help making EDC (Thermal, driver)

sorry I must be brief but no-one's replied so I'm compelled to chime in.
Welcome.

Anything can be modded. Be advised that you can order for $8 - $12 very bright multi-mode lights from Hong Kong dealers. So if you're modding for financial reasons, it's probably best you just order some lights.
If you're modding just to DIY, you might want to start with an easier host (i'm thinking p60 format, there are reflector + pill available,you add driver + emitter and put it in a surefire C/P/M compbatable host. All in this project parts for $20 or so?
Challenge with the light you've got may be the heat-sink. Most showerhead (lots of little led's) have them on a board with a reflector, but no base or heatsink to speak of. They'll also probably do something funny with the lens, so you have no good starting point for a reflector, a heatsink, a location for a driver. It's totally surmountable, but FYI you're starting with a lot more obstacles than is necessary.
Since you're new, I'd really like to see you start with an easier project. No need to tackle every flashlight related problem at the same time. I understand that those lights are the ones on hand, but my rough and ready judgement is that you could get two or three mod ready hosts up and running and then turn to the original lights you're asking about modding, and still have taken up less calendar days after then if you went head-long into the wallgreens lights and had to fight tooth and nail the whole way along.
Best,
Linger

 

[crosstalk]

Re: Need help making EDC (Thermal, driver)

Thank you for the advice, but I'll probably stick with my current light.

I don't need much of a reflector, I'll make this a floody light.

For heat sinking, I will probably mount the LED(s) to an aluminum plate (if I can get one) with the driving electronics behind that. This will all be built so that when you put it in, the spring connecting with the battery will push it up against the case (I will have some thermal compound in between.)

It will only be able to run on full brightness for a minute (before thermal protection kicks in,) but should be able to stay on until the batteries drain in low power mode.

I did find some 430 lumen Cree LEDs on Digikey (they were not labeled as high brightness modules,) but I would have to come up with the circuitry to drive them. However, I could probably fit four or five into the front of the light -- but the generated heat would be enormous. Besides, I couldn't power them anyway (well, unless seconds counts.)

As an alternative, are there any lights that are bright but don't need heat sinks, so I could practically drop them in (with a resistor?) I doubt it, as any bright LED also consumes lots of power and puts out lots of heat, but it's worth checking out.

Thank you.

Edit:
For Christmas, I got an Amazon gift card which I will be using to buy the Fenix mini LD01 flashlight to be my EDC, and may or may not return to this project in the future.