Building cheap homemade, powered by R/C car battery

My AP Biology class is going on a research trip for our final. One of the things my teacher suggested we bring is a flashlight or headlamp. I really want to build a nice, bright light for use on this trip.

I have a 9.6v RC car battery (8AA NiMh, fresh voltage: 10v) and I was hoping to get some ideas on what to do.

My idea was to have the battery on my belt of in a pocket attached to a headlamp of some sort. This means that it will need to be fairly light and compact.

For a lake/woods settings, should I go with lenses/optics or reflectors? 1 LED or multiple?

I am also looking for housing options and a source for parts. My budget is about $40 (shipping incl.)

How much mAh has that battery pack?

The_bad_Frag said:

How much mAh has that battery pack?

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It is listed as 1800mAh. The pack is pretty old, so its probably degraded some by now. I never tested its actual capacity.

Hmmm ok that should work...

You can take a look at my 8xAA test flashlight maybe you get some ideas from it. But I think you need to make your budget a bit bigger when you wanna have such a powerful light because that driver is pretty expensive... ...or you find a cheaper boost driver.

Link -> http://www.candlepowerforums.com/vb...cooling-*AA*&p=3601029&viewfull=1#post3601029

If I already have 10 or so volts, I would need a buck driver to reduce the voltage, not a boost driver.

I am really strict on this budget thing because I can get a good light for $40. I would rather buy something than build it for the same money, and while it may be fun, it is more convenient and reliable.

I have narrowed it down to one Cree XM-L on a headlamp. My questions that remain: housing options? reflector or lens/optics? store to buy parts?

aEx155 said:

If I already have 10 or so volts, I would need a buck driver to reduce the voltage, not a boost driver.

I am really strict on this budget thing because I can get a good light for $40. I would rather buy something than build it for the same money, and while it may be fun, it is more convenient and reliable.

I have narrowed it down to one Cree XM-L on a headlamp. My questions that remain: housing options? reflector or lens/optics? store to buy parts?

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Your best place to buy will be online. There aren't many brick-and-mortar stores that sell DIY-lighting optics for throw. Let's talk purpose, then you'll have an idea of what parts to get.

First, how much light do you need? Is this a night hike where your custom job will be too bright? If you spook all the animals off, you'll be in trouble. If you really are allowed to go wild on output, then are you lighting trees, land, or trying to see water? Water throws light away and makes it all dimmer.

I think you're going to want throw, maybe even using an aspheric lens. Those tend to make a larger lamp though, since the lens has to be a certain distance from the LED for maximum throw. I believe that that's called the focal distance. Standard optics are simply put on the LED, or put on a holder on the LED. Reflectors and optics both have to be rather perfectly centered for optimum throw, and the height from the bottom of the reflector to the LED is very important. One millimeter too high in a reflector will kill throw (This is how Mag Lites focus)

Housings are tricky. What tools do you have? Are you fine with a bolted-and-caulked construction? You're looking for a water-resistant box with caulk on seams that lets heat and light out the front. Take a look at the DIY Headlamp forum for some ideas. I think your biggest challenge will be losing heat. Is this for continuous-use? How much heat are you going to be dealing with?

Consider this driver. It won't stun you at 1.4A or so drive current, but it'll fire up and work. Click

@AnAppleSnail

Thanks for your reply.

By store I meant online store, because yes, not many retail stores sell LEDs or optics (Although the IKEA Janso lamp for $10 is pretty nice for hacking as you get an SSC-P4 and a small lens with a 700ma regulated power supply).

I know there are some optics/reflectors with centering features built in, so that shouldn't be a problem. From experience, reflectors have some spot and some spill, while optics/lenses are either wide spot or narrow throw. If I'm right, which would you guys recommend for walking around at night?

Ideally I would want multiple modes, so that I could set it low for this trip but high for other purposes.

I have access to a couple of tools, mainly a jigsaw, a drill press, files, and an angle grinder are my tools of choice.

What do you guys think? Will I be able to get a good result on this budget?

What is a good online store where I can order LEDs and optics/reflectors at the same time?

aEx155 said:

What is a good online store where I can order LEDs and optics/reflectors at the same time?

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DealExtreme.com is not good, but it works. They have cheap multimode drivers. I have used boost drivers with a resistor on the battery to make single-mode drivers into multimode; but without rebuilding your pack you'll have to buy a multimode one.

Carclo optics work well enough. I hear good things about LEDSupply.com, and there's their optics page. I don't know enough to tell you if a Cree XM-L will work with XP-G-made optics. I know that the beam pattern will be wider.

I bet that there is a list on this forum of good source sites, although I haven't looked. Also, try cutter.com.au.

I have decided that I can order my LED and driver from LCK-LED. Turns out they have a XM-L for $7 and a 3-mode driver for $8, plus shipping, which is approximately half my budget.

All that's left is a housing and a reflector.