Information Overload - Starting with the design

[kfarrar]

Batteries - Who can help

Even though my first attempt did not go as planned I figured I needed rethink my strategy, instead of starting at lights I guess I should start at the battery given that my rechargable cordless drill battery was not recommened.

So, what should I put together for a recharchable battery?

AA, AAA, 3v 123, C, D Lithium Ion Batteries?

There are lots of choices and I am thinking that a 12-14.8 battery would be good for a Helmet light.

 

[baterija]

Re: Batteries - Who can help

Unfortunately it's not as simple as starting with the power source. There's a delicate balance between what you want to power and the power source, to get the output and runtimes you need.. In your first thread you seemed to pick a light source that was going to be almost impossible for the runtimes you wanted, with any reasonably sized pack.

Instead of batteries I would encourage you to think first about what your requirements are that you want the light to meet. Right now your requirements aren't clearly expressed. If they aren't entirely clear in your mind jumping into design is premature.

Requirements I see listed in your first thread:
- 1.5 hours runtime minimum
- It's for skiing so probably needs to be durable for the occasional fall. I will guess an LED would work better for you for shock resistance.

Things you might want to think about for your requirements before starting to design:
- How big and heavy are you prepared to go for a battery pack?
- What kind of beam pattern and how bright do you need it to be?
- How are you going to mount/wear it? (affects size/space you have to work with)

You might want to read the stickied threads in the headlamps forum, and search for LED based mods here (especially of headlamps) to help guide you in developing your requirements. The bike lights forum might be useful too since there is some discussion of helmet mounted lighting in an activity where the speed affects how far out you need to light. Once you clear requirements up then it would probably be more appropriate to ask for design help.

Good luck and welcome. :wave:

 

[kfarrar]

Well, I have spent many hours reading since before and after my first post. It seems that there is wealth of information available here and very knowledgable people. I have received some good feedback from my first post.

I am in the market for a helmet / shoulder strap mounted light with a recharagable battery pack. I'd like to be able to get 300-500 lumens and two hours run time on max setting. The solution could include 1 or multiple lights.

So I need suggestions for the following:

1. Halogen vs LED vs Xenon
2. Light housing
3. Wiring Connectors
4. Batteries (Lith Ion vS NiMH) It is worth making your own? How many volts are needed?

Can a light and battery be put together for less than $100? Or am I crazy thinking it could.

Thanks for your help.

 

[Cydonia]

I have been working on exactly this concept myself. Here is what I have come up with so far. All sources take Paypal and have cheap Postal shipping options.
For an LED solution putting out 300 lumens I would do something like this:

1.) buy two of the Cree XR-E R2 for $6.56 each. They take Paypal of course.

2.) Search for and select a die cast aluminum electronics project box measuring about 4" long, 3" wide and 1" deep. Hammond Mfg., makes nice ones, waterproof silicone sealed, black powder coat paint OR bare aluminum for that cool industrial look. I buy them from A1parts.com in Canada. See their page on boxes here. They have a large selection of sizes, take paypal and ship with cheap regular Post.
​

3.) Build the light around the aluminum box. LED star's get Arctic Alumina ($7.70) epoxied to the outside face of box bottom (not lid becaue the lid is too small and has not enough mass for a heatsink. The silicone seal insulates the lid from the main box body). They are protected by a hard acrylic plastic "dome" of 2.83" diameter available for $2.50 from goldmine-elec (They do take paypal - see their FAQ on this page and scroll half way down - send them email with your order and they will tell you where to paypal the money.) Both Cree leds fit under the dome side by side. This of course is for a complete flood only. Optics may or may not fit under the dome.

4.) while you are getting the die cast aluminum project box at A1parts, go to their switch section and see Switch Accessories 2/3 way down the page and get a few "rubber switch boots" that match the threads on a switch. Be careful matching up the thread types. Buy a few switches. So you have waterproof switches to mount on the sides of the aluminum box. One switch per Cree.
​

5.) Get some battery holders from A1parts that fit the box you have carefully selected. I would fit 6AA Eneloops into the die cast aluminum box in the best configuration possible. 3 per LED, direct drive, with it's own switch.

6.) Check out goldmine-elec for heat shrink tubing. It is recommended on all solder connections inside the aluminum box.


So this was/is my plan for making a nice floody LED headlamp for under $100. Of course, attaching the finished aluminum box to a harness and straps is another story.


I hope this action plan can help others with ideas :D

 

[Cydonia]

I forgot to add that direct driven non regulated Cree's from 3AA Eneloop LSD AA NiMh cells will give you 2 hours high + diminishing light after that.
By having 2 sets of batteries and 2 LED's you have a dual redundant system all in one box. Low mode is with 1 led switched on. High mode is with both.
I'm posting this to give you ideas and sources for parts.
I don't believe for one minute anyone will actually build this design :whistle: It is far too robust and simple :devil:
(I can hear readers screaming "where are the cheapo LED drivers with inductor coils that love being dropped?!" :ironic: )

 

[Barbarin]

Well, I have spent many hours reading since before and after my first post. It seems that there is wealth of information available here and very knowledgable people. I have received some good feedback from my first post.

I am in the market for a helmet / shoulder strap mounted light with a recharagable battery pack. I'd like to be able to get 300-500 lumens and two hours run time on max setting. The solution could include 1 or multiple lights.

So I need suggestions for the following:

1. Halogen vs LED vs Xenon
2. Light housing
3. Wiring Connectors
4. Batteries (Lith Ion vS NiMH) It is worth making your own? How many volts are needed?

Can a light and battery be put together for less than $100? Or am I crazy thinking it could.

Thanks for your help.

That can be done with that money, but not if you don't have a host previously, or at least some skills to make your own.

Time ago I posted the "DIY poorman's LED caving helmet"

Nowadays, if you want something like 300 lm I would go for an overdriven single die, or an underdriven multidie. For a headlamp most of the handheld reflectors you can find over there are too narrow, and at the end you will be suffering pain in your neck. Try to look for a wide angle one.

I would try to make my own pack, a Li-ION one won't weight 2x18650 (less than 100 gr.) will be enough for your runtime.

Regards,

Javier

 

[Fallingwater]

>1. Halogen vs LED vs Xenon
LED. A Cree MC-E or SSC P7 driven at roughly half power (1.4 amps) would give you the brightness you require. You'd get a floodier beam with a SSC P7, which I imagine is what you'd want in a helmet light.

>2. Light housing
You could adapt an existing helmet light.

>3. Wiring Connectors
1.4 amps are safe for ordinary connectors, you don't need high-current special ones.

>4. Batteries (Lith Ion vS NiMH) It is worth making your own?
I'd go with LiIon: a self-built 2x18650 pack in parallel. Otherwise a single D-size LiIon would do, and would not require you to solder to the cells, but would be bulkier.

>How many volts are needed?
This depends on the driver you're using.
Personally, I'd go for one of these, since they don't have useless modes and are inductor-free so more resistant to shock; you need to add an AMC chip in parallel to the existing ones to bring the max output to 1400mA (from the original 1050). That driver requires a single LiIon cell, or a parallel-configuration pack.

>Can a light and battery be put together for less than $100? Or am I crazy thinking it could.
It is possible for the electronic side, but I don't know if you already have access to a light helmet/shoulder strap lamp you could modify. You could just get a junked helmet with a broken light, discard the guts and build your LED light in that...

The price of the electronics would be:
SSC P7 or Cree MC-E: US$20 - US$ 23
Reflector+heatsink combo for SSC or Cree: US$ 6.50
Two driver boards (one to use in the light, one to harvest a AMC7135 chip from): US$ 6.58
2-pack of 18650 cells: US$ 9
Alternatively, D-size LiIon: US$ 19
Switch: less than one US$
Wiring: price negligible
Heatsink goop: price negligible (do remember to use it though, it's important)

You shouldn't need protected LiIon cells because the driver stops working at 2.6 volts; a LiIon that gets to 2.6V under load will go back to safe voltage once the load is removed. However, if you want additional safety you could get these (US$ 10) or this (US$ 22) instead.
Also note that you'll need to add the price of a LiIon charger if you don't already have one.
If, for some reason, you don't want to use LiIon cells, you could build a decent pack with six NiMH AAs in a 3-series 2-parallel configuration. Or just use three C- or D-size NiMH in series. The price for that would differ greatly depending on which cells you chose, which brand and which capacity.

This would get you a dual-mode, impact-resistant light with a runtime of 2-3 hours and an output of about 400 lumens.

On a side note, the board from which you harvest the AMC chip will still work (provided you haven't munged it up during the operation), albeit at reduced power, so you could use it in another project.

Final note: I went with cheap parts because you specifically said you wanted to spend less than $100. If you had more money, you could get AW cells, which are generally regarded as the best there is (the price reflects this, though). Do note that Trustfire 18650s have been tested by CPF members and found out to perform quite well. The D LiIon from DX was tested as well, but I can't remember what the outcome was.

This should be all...

 

[kfarrar]

Thanks for the great information. I greatly appreciate it and will plan to investigate the components listed.

As far as a light housing, I do not currently have one. Is there one that people prefer?

Are the batteries rechargeable?
Could i use one Cree and SSC P7 to maximize flood and spot for distance?
What are the AW cells mentioned?

 

[Fallingwater]

As far as a light housing, I do not currently have one. Is there one that people prefer?

I have no knowledge whatsoever of helmets and shoulder strap lights (didn't even know shoulder strap ones existed prior to reading this thread). I could give you pointers if you wanted to build your light in a standard stick-shaped light, but the particular kind you want is outside my knowledge.

Are the batteries rechargeable?

Of course.

Could i use one Cree and SSC P7 to maximize flood and spot for distance?

Nothing is impossible given enough resources. You'd need to double the components and find a proper casing, but you could do it. However, you should first look at beamshots of P7 and MC-E lights (search the LED flashlights sub-forum to find them) to see if you really need that. P7s are powerful enough that their floody nature doesn't preclude a decent hotspot, and MC-Es have a large enough die that they too have decent flood, albeit less.

Edit: actually, if looking to use two emitters, you could just use a Cree R2 and a SSC P4. Combined they should give you the desired illumination level (though closer to 300 than to 400 lumens), they'd cost much less and heatsinking them properly would be much easier. You'd still need two boards, but you wouldn't need to futz around with AMC chips.

What are the AW cells mentioned?

The best lithium-ion cells money can buy. Or so they say.

 

[kfarrar]

Fallingwater - Thanks for answering my questions and helping me with the design. I like the AW batteries and will plan to use the cree 2 and SSC P4I think we are getting to reasonable design for my needs.

To secure a light to my backpack shoulder strap would be simple as I could epoxy some velcro to the back of the light. Even a money clip would work to connect it to my sternum strap on my packpack.

I prefer to keep the battery in my pack back so I will need to add the wire to the battery to connect it to the light.

The housing for the lights could be round or square. I have seen some nice mag light mods, but that would be large for a shoulder strap light. I think that I would not want it to protrude more than 1.5 inches off my strap.

So we now have confirmed the lights and batteries :)

 

[Fallingwater]

This what I'd do in your place.

1) get a small metal box of appropriate height and with a flat and reasonably thick bottom
2) use some thermal epoxy to permanently affix the two LEDs to the bottom of the box in side-to-side configuration. Keep in mind the reflectors will need space, so don't put them too close
3) wire up the LEDs and the boards. Each LED gets its own board, but the boards share the battery
4) affix the boards somewhere in the box so that they don't foul up anything. Make sure you don't let the boards actually touch the box. Double-sided tape of decent strength is a good idea
5) punch a hole in the box and screw/glue the switch in place. Wire it up
6) punch another hole and let the wiring from the switch out
7) Balance the reflectors on the LEDs, then use silicone adhesive to mate them to the bottom of the box. Make sure the silicone cures properly
8) close the box with a transparent plastic lid. Don't use glass as it's less resistant to impact, and you want impact resistance on a helmet light
9) wire up the battery holder(s)
10) affix the light-box to the support of your choice, but leave the back of it (where you glued on the LEDs) free to breathe, as it'll act as the heatsink

If a box with a decent bottom can't be found, use one with a thin bottom, but glue the LEDs on a metal heatsink and glue that to the bottom. Punch a few air holes in the box.

Use an orange peel reflector for the SSC (maximizes flood) and a smooth reflector for the Cree (maximizes throw).

This should give you a nice floody beam with a bright hotspot in the middle. Note that at close range the hotspot will be slightly offcentered, since it's coming from another LED.

Edit: actually, come to think of it, you might want to have two switches, one for each board, so you can choose which emitters to light up and at which mode.

 

[DM51]

Welcome to CPF, kfarrar.

I've merged your 2 threads to keep this project of yours together. It's best not to have too many threads scattered about, especially when they are discussing the same thing.

 

[kfarrar]

While I process all the information on this thread, wait for parts and time to assemble, I found and purchased a Pelican Big Ed flashlight so that I can use on my next couple outings.

The one mod I would like to make is to replace the 4 Alkaline C Batteries with some NiMH rechargeables that I can store in my packpack and run a cable from my pack to my shoulder. The lamp is a Xenon lamp and uses 7.2 watts.

Could this battery also be used to power my Cree 2 SSC P4 headlight.

Any suggestions?

 

[Fallingwater]

4xNiMH cells would run your DIY Cree/SSC with the driver boards I linked to just fine. C cells should also give you decent runtimes.
They would, however, probably underdrive the Xenon bulb.

 

[kfarrar]

Can you suggest a battery holder for Trustfire 18650's or CR123's?

 

[Fallingwater]

There isn't, so far as I can tell, a battery holder that'll let you just pop in those cells and use them as a power source.
When I had this problem I built a holder out of a small plastic box with a LOT of dremeling, ghetto-style. :p If I had to do the same now, I'd probably melt-glue terminals to this.

An alternative is to get a tube (plastic is better to avoid shorts) of the needed length, glue a spring terminal to one side and build some sort of positive terminal cap thing for the other. I did that with two releasable cable ties, but I can't post pictures right now because I don't have it here.

 

[kfarrar]

Would I be able to use a thin piece of copper to create terminals that I can sodder the wires to and then tape to batteries? I am thinking of running two batteries in parrallel to power the Cree http://www.dealextreme.com/details.dx/sku.16145.

I think I am going to start with one LED before experimenting with multiples, therefore building my knowledge slowly and not getting in over my head.

Duhhh! Any reason not to get some protect D sized liOns as there are many options of holders available? This seems like the most straight forward approach as there are no holders for 18650 and CR123s available. I guess I over looked this in FallingWaters earlier reply. Do you agree? I must admit that I am not comfortable making my own battery pack.

 

[Fallingwater]

Only reason are cost and shape. A pack of two 18650 is thinner and has about the same energy of a single D while costing less than half. However, if you don't want to hack up your own holder, the D LiIon cell is probably the best choice.

You don't really need copper for making contacts. You can hack the springs out of any throwaway battery appliance, and the positive terminal can be just a strip of metal (though you might need to add a blob of solder if the positive terminal of the cells isn't raised).

 

[kfarrar]

All suggestions answers to previous questions have been great. I know I am a noob at this but you all been helpfull. I am now wishing I went for the EE degree instead of an art degree. Good thing my neighbor as an EE degree. Hi Lawrence;)

Is additional heat sinking needed with the SSC P7 C-Bin LED with the 21 MM heat sink base?

I am going to try to build a light with 2 SSC P7s. I am still struggling with batteries and chargers as there are so many options. Leaning toward the recommended 18650's.

I still have not come up with a good housing option as the Hammond MFG cases seem large. I think they will be good for the batteries which will go in my packpack, but I want the light mounted on my helmet. I tried the strap mounted light with the Xenon Big Ed I purchased and did't like it. However, it could be just the weight of the Big Ed light. There seems to be some good examples using copper tubing and/or square aluminum stock. I think I'll order the lights and reflector first, then go shopping for a housing.

 

[kfarrar]

After searching for parts on DX, I decided to buy the following light http://www.dealextreme.com/details.dx/sku.19189 as it contains most of the pieces needed to build my dual led headlight.

I also purchased 4 trustfire 18560 batteries and a charger. I am guessing that these lights will be direct driven, so I'll need drivers to connect them together.

Would it be better to connect the batteries 2s2p or 4p? Do I need additional battery protection?

Thanks!