Freedive/Spearfishing light.. advise please!

[joethefish]

Hi all been lurking and reading through the CPF for a while now.
Im a freediver/spearfisher based in the UK and after managing to destroy my Halcyon 18watt HID light I need something new,
As a freediver I need something compact, the Hal was always too big and bulky, not to mention heavy.
Obviously I am considering LED.. for the same reasons as the rest of you and being a hands on sort of guy I would like to have a go at making something myself.
Basically my requirements are:
700+ lumen (UK water is murky most the time and I do a lot of night dives)
Burn time of 3hrs minimum, preferably with minimal loss of brightness
Tight focused spot (i never adjusted the HID out of its tightest 6deg. so something similar would be ideal.
Smaller package than the Halcyon! Infact if possible I'd like to go handheld as the canister configuration plain got in my way too often spearfishing and when shoving my head in holes etc.
That said I would consider a much more compact canister arrangement.. or both!

So ideas and suggestions please.. My current thinking is to mod a Mag light or make something out of PVC pipe.. obviously both are easy to come by and cheap. (in fact there are three mag lights in my garage ) That said I would gladly mod an existing light to fulfill my requirements.
I guess what gets created will depend on what electronics etc. need stuffing inside it and this is probably where I need most guidance as the whole field is newish to me. So suggestions of what LED, driver etc. to use to get enought light and a tight enough spot would be greatly appreciated.
Hopefully when I have a solid plan in place I can start a build and bore you all with pics of the progress!

Thanks in advance for your comments and suggestions.
Joe

 

[Codiak]

Welcome to the dive party.

First off let me say I love DIY! While cost savings were in the back of my mind when I first started playing with modded dive lights, by the time I had a reliable light I'd spent enough to pay for a canister HID. So a word of warning, if your hoping to save money just buy one. Packhorse, MB-Sub and 360 all have lights that meet your specs worthy of consideration at very reasonable prices.


If you still want to build your own your requirements seem straight forward.

• a P7 Led will get you 700lumens
• cheap macro Lense
• a couple 18650 batteries
• reed switch
• led driver
• housed in a cut done 2D mag light (by cut down I mean cut the barrel right below the current switch)
• a little solder, JB weld and silicon seal

If you read through the threads in this forum you should find all the details.
You'd end up with a Fixed focus 700 lumen fix'd focus non canister light shorter than a 2D Mag

I still suggest you start by looking at the lights for sale ;-)

Cheers

 

[joethefish]

Thanks for the info.. im well aware of ending up spending more than I should building my own anything.. its something I've never learnt from guess I just like building stuff..
Anyway your suggestions seem pretty spot on for what I was already thinking, any suggestions for reccommended drivers?
Also having read around somemore I'm also intrigued by aspheric lenses (guess thats covered by your camera lense mention though) but also by some of the newer LED's primarily the SSR-50 and 90.. yes they may be more complicated/expensive especially for a first time light build but as I know im gonna end up in this pretty deep I may as well go the whole hog!
Guessing my run times will be somewhat lower though, which may need a bigger body or a move to a canister.
Anyway I guess any other opinions of what might suit are much appreciated as are reccomendations of drivers etc.
Suppose I should also mention I dont need any multi mode stuff just on and off is fine.
Oh and I know you will also be saying try something cheaper first/buy something ready made etc. but wheres the fun in that! I'm a newbie to lights but pretty handy at making random stuff!
So let the thoughts commence!
Thanks again
Joe

 

[Packhorse]

Check out the aspheric mag link in my list of builds found on my sig line.
Biggest issue with that build is finding a driver but you could go direct drive. It would start off way over 700 lumen but soon settle to 1000 lumen or less as the battery drains down a little.
I do find I lose alittle voltage through the MOSFET due to low Vin so a toggle may be better. Or perhaps use 4 NiMh cells and 3 1400ma AMC 7135 drivers running a SST-50.

Such a build required no special tooling except to make the heat sink.

 

[joethefish]

Thanks packhorse,
I was just reading through the thread and it looks spot on for what I was hoping for, as you said the only issue I forsee is the driver. I see your making a constant current driver (is that correct) to my eyes that seems like the best solution. Can you share any details of how your doing it or what parts are required.. IIRC your building it for dual power settings something I wouldn't use.. all or nothing for my application Im guessing a single power setting driver may be simpler or even already availiable if one is please feel free poit me in the right direction.
As a side note have you tried or considered the SSR90 without its dome? Elsewhere on the forums its mentioned as increasing throw and tightening the spot although that was with a reflector, do you think similar could be true when using it with an aspheric.
Thanks for the heads up and thanks in advance for the pointers!
Joe

 

[Packhorse]

Well no. I was trying to make a CC driver but it didnt quite work out. The AMC's didnt seem to pass enough current but I dont really know why.
As it is at the mo I use a constant voltage reg with thermal feed back. I can set the voltage to what ever I want and then as the light heats up the voltage/current drop. Its not idea but it works and should stop the LED going into thermal runaway.
I did try a domeless SST-90 ( by accident). It gave a much tighter spot and also a much wider beam at the other end of the scale due to its ability to get closer to the aspheric. Unfortunately it blew and I am unsure why. I may have over driven it or it may have had something to do with it not having a dome. With the 44mm DX aspheric the spot is tight enough with a domed SST-90 so I wouldnt recommend knocking one off on purpose.

 

[joethefish]

Ok.. guess it is too ££ an led to go breaking on purpose with fingers crossed!
Right so I have a plan in my head now just need to settle on some form of driver.. any ideas on my best course of action, what drivers are others using to run them? Hopefully can avoid building something custom. Are there any dedicated drivers lined up to come out to the market?
Oh and while im at it can anyone tell me or point me in the direction of a calculator to calculate run times with the led and different choices of batteries.. I did have a nice online one bookmarked but it seems to have vanised!
Thanks for the help so far hopefully be starting a build sometime soon!

 

[Packhorse]

There are no real drivers for the SST-'s yet so most people improvise. Best you do a search.
run time calculator.
Vf of LED X current = Watts
Ah of cell X Nominal voltage of cell X number of cells = Watt hours of battery pack.
Watts/watt hours= run time
Subtract driver/wiring inefficiency and also battery inefficiency for given discharge rate and you get pretty close to actual run time.

 

[joethefish]

Lovely cheers for that, think i've found my potential driver too I was considering making do/modding something to fit but looks like there is a chap not far off ready to produce them he is doing a bit of a write up in the LED forum bit i think. So might hold out for that as its much better looking than anything i'm liable to cobble together and will hopefully work a lot better too!
Cheers all and watch this space..

 

[joethefish]

Ok as i'm impatient I started searching around for driver solutions and came across this:
http://www.murata-ps.com/data/power/lsm2-t30-d12.pdf
Any thoughts on its suitability for my plans? (Single SSR 90, in mag head with aspheric lens.. possibly handheld possibly canister depending on battery requirements)
Spotted it was being used in a project or two on the main forum.
So will it work.. is it overkill (not neccesarily a bad thing) any better suggestions without making everything go
Cheers all..

 

[Codiak]

Nice find, the description seems right for the use and the price isn't too bad.
It's larger than "typical" drivers but form factors can be overcome too.


Hopefully someone can provide definitive answer so we can get on with building ;-)

 

[joethefish]

Thanks for th reply, it seemed to read as the right tool for the job to me but having not done anything with LED/drivers before I wasn't sure.. the size is an issue I guess but I think i will abandon my thoughts on a handheld as the chance of me getting enough batteries into a handheld unit to give me 3hours+ runtime are slim enough without having to squeeze this driver in too. If I bite the bullet and go for a canister it should leave me plenty of room for the driver and give me a few more battery options.
Also awaiting a definitive answer before I bite the bullet and buy some bits!
Joe

 

[Codiak]

Form factor for this driver would work well for my build

You could build a flexible power source much as MB-Sub has on his systems.
It looks to me like an RCA plug and cable system.

I'll be changing my canister over to it in my next build.

Just wish I knew the voltage whether and the Pin or the Sleeve was +.
Just in care I breakdown and buy one of his head units in the future.

Next up for me is a SST-50 Canister with Variable Focus.
If the build works as I hope, new video lights will follow immediately after with the SST-90s.

 

[Packhorse]

Its not the right tool for the job. Its a constant voltage regulator not constant current.

It can be used though but the current to the LED will drift. As the LED gets hot it will draw more current (at the same voltage). You can put a thermistor in the circuit to give it some feed back but you will still not get a constant current. It will help save the light from burn out if used out of water though.

There may even be the possibility of wiring it up in such a way as to make it constant current since it has a sense voltage input that could be wired up to a shut resistor but that is not something I know much about.

 

[Codiak]

Its not the right tool for the job. Its a constant voltage regulator not constant current.

Definitive enough for me... there was a discussion on another thread with similar details.

Thanks Packhorse

 

[joethefish]

Cheers packhorse.. will continue my research on this driver and keep looking for another as well.. im hoping to build this light once and right so will keep looking for a more ideal solution and if that fails then start considering others.. while im thinking about other solutions.. what are the pros (if there are any..) and cons of direct drive.. obviously you loose your power level switching bu thats not a concern for me as I am used to one power level so cant see an issue with sticking with one.

 

[gcbryan]

Cheers packhorse.. will continue my research on this driver and keep looking for another as well.. im hoping to build this light once and right so will keep looking for a more ideal solution and if that fails then start considering others.. while im thinking about other solutions.. what are the pros (if there are any..) and cons of direct drive.. obviously you loose your power level switching bu thats not a concern for me as I am used to one power level so cant see an issue with sticking with one.

Read posts #78-81 below for some good info on direct drive...

https://www.candlepowerforums.com/threads/228494&page=3

 

[Codiak]

Okay, so as I understand the real issue with Current is the SST-90 draws more as temp increases. So why worry about constant current below 10A if the LED can handle it? What we really need is a limiter? Do I correctly understand the issue?

If so, as I read the details for this board, current is limited to a max of 10A. Note: it doesn't say cut-off/shutdown... just limited... isn't that what we need?
http://www.batteryspace.com/pcbprot...r2cells60vlifepo4batterypackat10alimited.aspx


Are we good with this coupled with a good buck driver?

 

[gcbryan]

Regarding needing to go to a cannister design to get 3+ hours, that isn't the only option.

Unless you are on a rebreather you probably aren't underwater for 3+ hours at a time. You can have a small hands free hand held model that will give you 700 lumen and will burn for 2 hours using two small 18650 li-ion rechargeable batteries not much larger than AA cells. I get mine for $8/pair.

Just switch batteries after 2 hours and you get 4 hours of burn time without the cannister. Since the batteries are so small it's no hassle to carry them and with li-ion even rechargeable batteries keep their charge for quite a while so it's easy to take a few on a long trip.

 

[gcbryan]

Okay, so as I understand the real issue with Current is the SST-90 draws more as temp increases. So why worry about constant current below 10A if the LED can handle it? What we really need is a limiter? Do I correctly understand the issue?

If so, as I read the details for this board, current is limited to a max of 10A. Note: it doesn't say cut-off/shutdown... just limited... isn't that what we need?
http://www.batteryspace.com/pcbprot...r2cells60vlifepo4batterypackat10alimited.aspx


Are we good with this coupled with a good buck driver?

Other's more knowledgeable will chime in but the buck driver is the limiter, the battery pack will shut down at it's limit both with overcharge and at the lower limit, and constant current isn't necessary but is used if your want ...constant current...constant brightness throughout the burn time rather than a longer burn time at decreasing brightness.

Maybe I'm just stating the obvious and haven't completely understood your question!