Making a DIY caving light

[Cvile (Borna Maleš)]

Hello, im new to this forum and the world of flashlights.
Im designing a caving light. It should look something like Scurion, El Speleo, Phaeton ect.
Im thinking of using one Cree XM-L2 led and other Luminous SST-40.
Thinking about two 21700 batteries connected in parallel for 10000 or 12000 mAh of juice.
I will use carclo 20 mm optics, one for spot and one for flood, or just one for spot.
Im looking for a driver that can run leds in few mode like 25 50 75 100 percent or smth like that. No strobe or SOS driver from Aliexpress. I know that sst-40 is maybe an overkill? it gets pretty hot on higher amps.
For battery pack and casing i already have an idea for CNC milling and 3D printing.
As I said im a begginer in electronics and flashlight designing so I ask you for advices or any ideas for my project.

1. Im thinking of pre made driver…any suggestions for that setup 3.6v…
2. Is there a way to have heat regulation and battery status level in a driver?
3. What are the things i need to take in consideration generally?
4. What sites to order stuff from ( Preferably Europe)
5. How doable is this for someone inexperienced?

I would like to post updates on this topic here about the project.
Kind regards,

Cvil3

[raccoon]

You’re going to love it here, Cvile!

[Cvile (Borna Maleš)]

I bet I will

[gravelmonkey]

Welcome to the forum!

What you propose is certainly a significant scope of work, but without knowing your skill level it’s hard to advice whether it’s feasible for you to achieve.

I’ve seen new users ask similar “is it possible?” Questions with mixed results. Perhaps when I have time I’ll curate a list of these to encourage other beginners.

Some comments I hope are helpful:

@Cvile

one Cree XM-L2 led and other Luminous SST-40.

Any reason these two in particular? For flood you could look at the 3v XHP LEDs, for spot SFT-40.

Think about what colour temperature you want. Cool white is brightest and most efficient but can wash out colours.

@Cvile

a driver that can run leds in few mode like 25 50 75 100 percent or smth like that.

You’ll want a 2 channel driver to control the LEDs separately. Due to the nature of how we perceive brightness, you need 4x lumens for an apparent 2x brightness.

Don’t discount a low mode, you might be glad of the long runtime one day…!

@Cvile

two 21700 batteries connected in parallel

This seems reasonable, if you build a 1S2P pack don’t forget a BMS. You could also put the cells in series with a 8.4V BMS, but driver options are a little more limited, I think. Always use quality cells from a reputable supplier, and ensure they’re “matched” (same make/model, same age/history).

It is also possible to use a cell carrier (if you can somehow make something waterproof and easy to change the cells). Just be mindful the cells should be a similar level of charge before you put them in the carrier else the higher charged one will try and charge the lower charged one with a LOT of amps.

@Cvile

battery pack and casing i already have an idea for CNC milling and 3D printing.

Okay cool! If you’re good with CAD and can get stuff machined, then I think this project is feasible. In my opinion, the housing is potentially the most difficult step to get right.

@Cvile

sites to order stuff from ( Preferably Europe)

Most of the flashlight specific gear I’ve acquired is from China.

Good places for stuff are https://kaidomain.com/ for lenses, optics, switches, o rings, drivers, LEDs;https://intl-outdoor.com/ for drivers (have to send Hank message), o rings, lenses, emitters; https://convoylight.com/ for emitters, drivers, lenses, optics, switches.

[Cvile (Borna Maleš)]

Hey gravelmonkey, thanks for the reply and ideas.
I wanted parallel just for the runtime. I was looking at xm-l2 just becouse it is known as reliable and good emitter at its max 3A and i already own a caving light that uses two of those (doesnt mean its the best choice)

What are pros to SFT over SST?
SFT (if im not mistaken) only comes in 5700K or higher kelvins while SST has 5000k version.
SFT is domeless so its better suitable for spot but i dont know can it fit carclo optics? its 2.25x2.25 in size
Do they heat the same?
Do you know any specific driver for that needs?
Talking about XHP led…do you mean like 3up or 4up versions bc i know they work on 3v but pull crazy amount of amps.
Thanks again for your answer, helped a lot to start considering different configuration.
Hope you reply back

[L4M4]

SFT have no dome, SST have a dome.
No dome equals better throw which you surely want for the thrower portion of the light.

Since those LEDs are dirt cheap at Convoy, I would say you should just buy a selection and test them yourself.

My list would be:

Maybe you can see, which of those LEDs I like the most

The SFT25R would probably be the best for throw since the DIE is the smallest of those that I chose.
The 519A has the best light quality of them all.

The LMP is my favorite right now because it is super cheap and gives a lot of light that is a super nice cold white. Like, super super nice.
I usually don’t like cool white light, that’s why I alsways chose the 5000/5700K Version, but the LMP is just so perfect cold white!

Convoy has plenty of drivers, but which one will depend on how your case will look like and if you want a light that you usually use at ~50% but want that overhead for short uses or if you want to use it at 100% all the time.

Also - do you want both LEDs to be on in the same time or do you plan on having them seperated? That would make the driver search 200x more difficult.

I would use a single 21700 and carry some replacements - if you have a 2x21700 Battery Pack you cannot just switch it out if you need to.

Also, let me leave this here…

[Haukkeli]

One option is to use separate driver for each led and have 2 switches. One switch for each led/driver.

[Cvile (Borna Maleš)]

Hahaha, thats about it from the photo…Well I was thinking while flood is off spot is on and vice versa, not at the same time, if there is a driver.
I was thinking Dr.Jones or Led4power, taskled is too pricy with shipping…
Can I drive each led with its own driver and still have only one push switch?
I will sure check convoy, thanks

[Haukkeli]

Dual channel drivers are rare. Those would allow you to use 1 switch for 2 leds.

[zoulas]

What is a caving light.

[gravelmonkey]

@Cvile

wanted parallel just for the runtime

I think the actual reason you want parallel is for “off-the-shelf” driver availability. 2x 21700 arranged in parallel or series have the same watthours, so runtime would be the same.

@Cvile

pros to SFT over SST?

Think this has been answered satisfactorily.

@Cvile

XHP led…do you mean like 3up or 4up versions bc i know they work on 3v but pull crazy amount of amps.

No I mean for your floody channel a single XHP. They are available in 3V if you’re limited to 3V LEDs due to whatever driver you choose. LEDs in triple or quad arrangements don’t get hotter then a single LED, assuming you’re producing the same amount of lumens for each arrangement. The multi-led setups often push more current for more lumens, which obviously means more heat.

@L4M4

would use a single 21700 and carry some replacements - if you have a 2x21700 Battery Pack you cannot just switch it out if you need to.

This is a good suggestion, however, I’d suggest a backup single 21700 and a waterproof connector. If you’ve a parallel battery pack, the voltage is the same as a single 21700.

@Cvile

Led4power

I’ve not seen L4P gear for a long time since they closed down their store.

@Haukkeli

Dual channel drivers are rare.

Most of the e-switch drivers Hank (Emisar) uses are dual channel… No?

@zoulas

What is a caving light.

Ruggedized headlamps specifically designed for caving activities. This is a search engine question if you’re genuinely curious…

[L4M4]

I found this reddit post:
https://www.reddit.com/r/caving/comments/teox37/diy_caving_light_coming_along_housing_and_lense/

And I find it quite interesting.
What about two triple or quad 3535 boards with different lenses?

Convoy has 10, 30 and 60° for their Quad boards:

Quad TIR lens for S21D S21F 3X21E

Board:

519A LED , high CRI R9080

Then you wouldn’t have different light colours.
Maybe you could also use just one driver and a on/on switch between driver and LEDs to choose which one you want to use?

Maybe a very throwy light in your hand? Comething M21B or C8 size with one KW CSLNM1.TG

[Haukkeli]

@gravelmonkey

Most of the e-switch drivers Hank (Emisar) uses are dual channel… No?

Yeah, he offers dual channel drivers. Not the most efficient ones, but they work. OP should also look how current dual channel Anduril works and if it’s what he wants from a caving light.

[Cvile (Borna Maleš)]

Here is the update…i didnt have much time to work on the lamp so im back now again…
Im starting to catch up again.
I made a 3D printed 1s3p housing for 3 21700 cells that will be mounted on the back of the helmet.
Will be using SFT40 led for spot with some 23mm optics at maybe 10 degree angle.
Im still not sure about the flood light led…sft pulls 8A and i dont know which other to use if im going to be driving them from the same driver.
The battery will be closed waterproof case with barrel jack connector outside of it (it connects to lamp inside the helmet space) and it will be used for charging and power output via BMS (1S 10A)
I will spot weld the batteries with nickle strip and connect the dedicated inside the battery pack itself.
I plan on using rotary switch and that is my main question for you today…
1)Is 18 AWG (0.75mm2) cable thick enough for such amps?
2)Recomendation od other flood LED choice
3)Recomendation on driver options
4)Can i wire single driver to run leds indepenendtly (one is on other is off) and if so what kind of switch to get?
5)how can i wire it so that i dont use the bottom part of off the shelf driver so i can mount them with thermal paste on the alumium housing? are there any drivers avaliable that dont use spring style connections?
6)any other advices or questions?

I know its kinda mess but i came back to this project of mine after a long time

Thanks for your time people
Hope you reply

Cvile

[YuvalS]

I know someone who build something similar

This light is from scratch:

YuvalS's Hand Made Class, 7th Annual BLF/OL contest entry topic

So I am planning on building a headlamp, hopefully I will finish it by February. The body will be made of aluminum to double as heat-sink and the battery box will be made of some kind of plastic. both will be build using hand tools. I want to print my own driver but I have no experience with printing circuits so maybe I will use a commercial driver and modify it. As a FW I am planing to use my own code that is need some improvements. Welcome to share your thoughts. Yuval EDIT: 2…

This one is inside an old Elspleo (I have sone hosing for sell if you interested)

YuvalS's Modification Class, 8th Annual BLF/OL contest entry topic

For this year's competition I decided to renovate an old dysfunctional caving light. Some time ago, I bought a box full of defective caving lights that people sent to the retailer for repair under warranty and he decided it is not repairable. I think the contest is a great opportunity to repair one of these lights and bring it back to life. [image] The lights were sealed with glue and in "not so good" condition, but I am mostly interested in the body so I choose one that seems nice [im…

And this one is inside an old DUO

Petzl DUO caving light modification

Anyone who has followed my previous projects can guess that this year too I will build a caving headlamp I.e.: a super durable, helmet mounted headlamp with a dual optics. For this year challenge, I want to rebuilt a classic caving headlamp: the Petzl Duo Since the 90's this light considered as the best caving light by the many cavers because of its great durability and waterproofs. During the years many upgrades to the original light tried to keep it relevant with recent LEDs impro…

And another one from scratch

YuvalS's Hand Made Class, 10th Annual BLF/OL contest entry topic

This year I am joining the party relatively late. As every year I will build a caving headlamp but the innovation this year will be in the user interface. I plan to create a switchless UI, using voice commands. The reason I'm toying with the idea of a caving headlamp with voice recognition is that it is very complicated to switch between all the possible lighting modes of a dual optic headlamp: focused, diffused, combined and all different intensities with using only one or two switches. I'v…

[YuvalS]

@Cvile

1)Is 18 AWG (0.75mm2) cable thick enough for such amps?

No. But I don’t think you really need 8A and it is easier to keep it lower current, it enable you to use thinner cable and reasonably small connectors and cable glands. also high current = a lot of heat = huge heat sink.

@Cvile

2)Recomendation od other flood LED choice

Related to previous section try use both emitters the same so they mix better if you plan to use them both at the same timer (I don’t mix)

@Cvile

3)Recomendation on driver options

TaslLED offers a dual channel driver that is really useful for DIY caving light. I is the one pantheon caving lights have inside. I have used it in some of My builds but stop used id because of high price and lack not so good UI in my opinion.
My go to driver nowadays is simple AMC7135*8 running my FW (available on GitHub) and a slave board for the 2nd channel.
I am currently working on a project to enable easy FW generation for multi channel driver that may be useful fore you

@Cvile

4)Can i wire single driver to run leds indepenendtly (one is on other is off) and if so what kind of switch to get?

Yes you can wire a toggle switch on the input/output of the emitters and switch between them but waterproofing a toggle switch is delicate and not easy to find 8A small toggle switches.

@Cvile

5)how can i wire it so that i dont use the bottom part of off the shelf driver so i can mount them with thermal paste on the alumium housing? are there any drivers avaliable that dont use spring style connections?

Yes the one from TaskLED but basically you can de-solder the spring from almost any driver

@Cvile

6)any other advices or questions?

Why do you need 3*21700? it is bulky and heavy.
My 2 cents on caving light battaries:

1. Use the same batteries for all your lights. If your main light is using 21700 make sure also your backup light is using 21700 (and also you 3rd backup that you must carry when using DIY light as a main)
2. Don’t spot weld the batteries so you can use the in your other lights

[Cvile (Borna Maleš)]

Whats i a slavbe board?
I want to use the batteries in a closed system and carry one spare in my pouch.I dont want them removable form the pack itself rather from the helmnet…maybe two 21700 in parralel becouse my main is big runtime on medium modes for general caving…i want one that can shoot far with soke narrow optics and other that will also have optics (maybe 45 degrees) for general moving from the cave and crossing anchors…i dont need normal flood without optics.
I saw some of your projects and i really like them. I will draw the housing in Freecad and my friend has a CNC mill and he will make the housing for me,
What do you think about having two seperate drivers (for example one thaht is rated 3v 3A for example cree xml-2 for flood 45 60 degree lens and other maybe 3v 6A driver for some dedomed led maybe sft 40 for narrow optics?
I didnt plan on having them run at the same time becaouse i dont need such setup.
I guy from my country makes diy caving light and its reliable and everything but i would like to have some more lumens (his emits around 1100) and he is using one driver to control 2 leds on off one on with ON OFF ON rocking switch like old el speleo.
He is using some basic off the shelf driver that he heatplastered to the housing and connected SWITCH DIRECTLY to Lpositive and L negative.

Thanks for the reply, cheers

[Cvile (Borna Maleš)]

Looking at the old el speleo you moded…how did you wire the leds to run using only one push button switch with 2 pins?
Can i do so or is it firmware related?

[YuvalS]

@Cvile

Whats i a slavbe board?

This is a “driver” with only current limiters controlled by the master driver , you can see the wiring here:
YuvalS's Hand Made Class, 7th Annual BLF/OL contest entry topic - #87 by YuvalS

@Cvile

I want to use the batteries in a closed system and carry one spare in my pouch.I dont want them removable form the pack itself rather from the helmnet

Why? what advantage it have over loose cells? Make a battery box for loose cells and never open it if you don’t want but you always will have the option to take or give a cell in case of emergency
Also remember that charging 3*21700 in parallel wit take ages even with 2A charger. Usually in expeditions not a lot of sockets are available and you want to be able to charge it fast in external 4 bay charger…

@Cvile

I will draw the housing in Freecad and my friend has a CNC mill and he will make the housing for me,

If you have a CNC you may want to have a look at this project

La Light1777 V.3.0

And also in this blog that build some lights using the above housing

La L1777 de Nanard - Speleled

Both in French but google translate can help

@Cvile

What do you think about having two seperate drivers (for example one thaht is rated 3v 3A for example cree xml-2 for flood 45 60 degree lens and other maybe 3v 6A driver for some dedomed led maybe sft 40 for narrow optics?

For the speech recognition light I have used 3 deg optics with XM-L2 not sure you really need more. Keeping the current up to 3A make everything compact and relatively efficient. You can de-dome the xml or use other 3A LED with better throw.
Using 2 different drivers has an advantage or redundancy, it is kind of 2 different lights in a single housing but I don’t like this type of UI of 2 switches for 2 LEDs.

@Cvile

I guy from my country makes diy caving light and its reliable and everything but i would like to have some more lumens (his emits around 1100) and he is using one driver to control 2 leds on off one on with ON OFF ON rocking switch like old el speleo

It means that you are probably Croatian

@Cvile

Looking at the old el speleo you moded…how did you wire the leds to run using only one push button switch with 2 pins?
Can i do so or is it firmware related?

It is FW related but you can do it, my FW is on GitHub

GitHub - YuvalSob/CavingHeadlampsFW: All my FW for caving headlamps - See Readme...

[alpg88]

How far do you need to reach in the caves? If under 200ft? then do you really need that narrow beam? medium flood will reach that far, and be your upclose light as well, especially with frosted tirs. Why needlessly complicate things.