Scubadiving lamp with 3 Seoul P4

Hi all,

I often read threads on this forum but it is the fist time I write one.
Hoping I write in the good category.

So, I would like to have your advice about my project :

3 Seoul P4, powered with 3.8V and 1000mA thanks to this regulator : http://www.leds.de/product_info.php?info=p296_Constant-current-supply-1000mA.html

Do you think it is a good choice ?
Do you see any technical problem ?

What width should i take for the lense ?(do not forget it is for a scubadiving lamp)

I forgot, I choose this batteries to power my lamp : http://cgi.ebay.fr/4-Piles-recharge...yZ100748QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Share me your advice please
winzo

You could also buy a prebuilt 4 Edison opto(Similar performance to the Seoul) divelight by Barbolight(the Barbolight T-15 seems to fit you description, too bad the sales thread is closed).

My question is what you choose to put every thing in.

Welcome to CPF!

HI,

I must say that is a very nice light. :thumbsup:

But I already have some stuff for free : I just need to buy the battery, the regulator and the ligth. So my lamp will be less expansive than buy a barbolight.
Moreover I want to try to make one by myself.

" My question is what you choose to put every thing in. " :thinking: what !
Do you mean, why I do not make a bi-bloc light ?

Thank
winzo

What I meant is how will you house everything, will it be in a custom body or what?

What you are trying to build seems something like this(the 2 C one), or this except waterproof and with more throw.

I think the Shark converter will be perfect for your project, and you can even add the Remora board if you want multiple modes(wire the emitters in series).

What kind of reflector/optic/lens depends on how big of a space you have. If you have enough space, you could buy three of these drop-ins, wire them together and power them up.

Have you though about powering you light with lithium ion rechargeable batteries(most common being the 18650 3.7v rechargeable battery, capacity form 1800 mAh to 2200 mAh, 18 = 18mm in diameter, 65 = 65mm long and 0 = round).

Moving this to Homemade and modified lights might get you more experienced answers.

Hi Gunner 12,

Ok, my light will be more like this, I have all stuff to make it at school.

The shark converter looks really good for my project !
I do not want to make multiple mode. But it's great to know it for a next project.

I did not think to the li-ion battery because of the charging problem.
But nowadays, it seems to work well.
Moreover, I would need 4 rechargeable batteries,they will take as place as 10 Ni-Mh Batteries.
To fit well in my hand, the "handle" should have these dimensions : L=120mm D=50mm max.

Perhaps Li-on batteries have others advantages that I do not know ?
What will you choose ?

About the reflector/lenses , I would choose this, but thanks to this very interesting web site , I think it should have better one.
Those you adviced me look a little bit too big, the total diameter of the head must not exceed 60mm and the degrees of the lenses should be about 10°C.
What could you advice me with these dimensions ?

Thank for all your advise.
winzo

P.S. : please moderator remove my message at the good place.

the mag lite mod cannot be water proof...

even if you seal up the gaps, it will not be alot more water proof...

You could probably ask Barbarin about dive lights.

The Seoul P4 emitter is available for $6.35 USD or about 4.67 Euro with shipping at Dealextreme. Be careful of the positive slug, you don't want any shorts. The Dealextreme Seoul Stars(the original stars should have no problem) had some problems with heat transfer so I would not recommend them. This optic will also fit the Seoul LEDs though I'm unsure of the quality.

The main problems Lithium Ion batteries have is overcharge(above 4.2v), over discharge(under 2.7v) and too much current draw. Either one will damage the cells and might cause an explosion the next time you try to charge the batteries or a loss in capacity. There are protected cells that have a circuit that prevents overcharge, over discharge, and over current by shutting down the cell. Though protected batteries might be bad if you are using it under water, I don't think you would like your light to shut down all of a sudden due to the batteries being too depleted. Li-on batteries are 4.2 v off the charger.

Newer LiFePO4 batteries, Quote form wikipedia "LiFePO4 cells have higher discharge current, do not explode under extreme conditions and weigh less, but have lower voltage and energy density than normal Li-ion cells.

O bond is stronger than the LiFePO4 is an intrinsically safer cathode material than LiCoO2. The Fe-P-Co-O bond so that when abused, (short-circuited, overheated, etc.) the oxygen atoms are much harder to remove. This stabilization of the redox energies also helps fast ion migration. Only under extreme heating (generally over 800 °C) does breakdown occur, which prevents the thermal runaway that LiCoO2 is prone to."

You should be able to fit 4 18650 batteries in you light. Presuming 3.8 watts per LED(maximum for the Shark) and a capacity of 1800 mAh per battery
3.8 * 3 = 11.4 watts
3.7v * 1.8 Ah * 4 batteries = 26.64 watts of power
Presuming 85% converter efficiency
(26.64 watts * 0.85) / 11.4 watts = about 2 hours runtime at at least 300 lumen of light.

The one thing I do not like about most collimators is their lack of spill, though this might no be a problem underwater. Since water diffracts light differently then air, a 10 degree beam in the air will be a different angle in water.

A picture of the Light's body might help with advice.

I don't know much about dive lights or making a light from scratch so everything I say is from what I have seen/read.

Hi,

Thank for all Gunenr 12,

I choose NiMh battery and not Lithium.
It is less dangerous !!

About the leds, I thought buying them on leds.de.

I add a graph of the lamp.
It is not mine, but it is quite the same of my prototyp.
L~200mm, Dmax~80mm and Dhandle~60mm.
The holes under the leds it is for watercooling.

Thanks
winzo

I'm glad I could help.

I want to know, why the water-cooling holes? Wouldn't the metal itself act as a heat sink and absorb the heat. The metal contacting the water should transfer enough heat to the water to prevent overheating. If you want better cooling, isn't it simpler to fin the metal under the LED?(finning the should give you more surface area then putting holes in the metal and it looks simpler) Putting those kinds of holes in a light seems to be complicated(I wouldn't know, I haven't made anything on a lathe yet).

Either way, it looks to be a great lamp(When you are done, could you put up pictures of the finished light?).

Hi Gunner12,

I choose to make some holes to be really sure that the heat will be absorb.
Indeed, the output light of the Seoul P4 decreases a lot with the heat.

Could you help me to choose the lense/reflector now you know the size of my ligth.

And about the electronic system, this one is it good ?
The datasheet of the P4 are here.

@ Barbarin, you may know a lot about dive light.
What do you think about my project ?
Could you give me some advice please ?

Thanks
winzo

Send Barbarian a PM, it will be faster.

I think that fining the head(sort of like a CPU heatsink) will give more surface area and easier water flow which should amount to better cooling the holes(Unless you use some sort of compressor to pump water through the holes).

I think the Shark Converter will work for your mod, you don't have to add the Remora board if you don't want modes and all you'll need is one board. I don't know about the regulator you linked to, do you know it V-out?

The Cree Q5 will actually be more efficient(Cree Q4 testing thread) then the Seoul P4(and more expensive) and I think the Cree is more resilient to heat and better with optics.

About the optics, I can't help much but say that you'll need a narrower beam to project further in water.