underwater light

[RWE]

I am rebuilding/refurbishing an underwater light and would like to use a LED bulb rather than the original halogen. The original light used 30-50 watt halogen bulbs and was 12 volts. I can use lower voltage battery without problem. I would like the new light to provide a white light and be as bright as a 30 watt halogen or greater. Is there an LED available that will fit my needs?

I have seen some ads on ebay for 1000 lumen lamps. Are these real. Can they easily be connected to a heat sink and used?

Thanks for your help,

 

[Packhorse]

What sort of halogen does the light take? Is it MR16 or MR11?
If so try a P7 LED and 52mm reflector from DX.
Check out a few of the threads I started. They should give you some ideas.

 

[RWE]

What sort of halogen does the light take? Is it MR16 or MR11?
If so try a P7 LED and 52mm reflector from DX.
Check out a few of the threads I started. They should give you some ideas.

The light head uses a standard simple halogen bulb and has its own reflector which is removable. The reflector diameter is between 49 and 50 mm. It looks like the DX reflector could probably be ground off slightly with my Dremel to make it fit. How careful do I need to be about vibration to the led if I grind the reflector down slightly? Would you this consider the P7 module a better option than using the Terralux LUXEON K2 LED BULB replacement for the D cell maglite?

I have seen several mentions in this forum of using a thermal sealant to seal to the housing (aluminum in my case) to enhance heat removal. Can you define a specific product?

Thanks for your input,

 

[gav6280]

Welcome to the forum, there is a fair bit of information on here that relates to your dive light situation. Just have a search through using the search function at the top of the page.

In your case it might be good to tell us exactly what the torch is as it might have already been modified by someone else. And if it has not it may help to post a few pictures.

People that have been pretty active with regards to dive lights of late are ME, steve6690, Packhorse & Barbarin + Many others.

 

[Packhorse]

http://www.candlepowerforums.com/vb/showthread.php?t=203029

Sounds like the P7 reflector could be made to fit. Its a separate reflector so add the P7 after you have cut the reflector down.

I have not seen the Terralux or know much about it. But the P7 looks like a cheaper option and is rated better. It all comes down to what sort of beam you want.

 

[RWE]

The light is a Tekno Light by Omersub. It is an old light made by an Italian company that I purchased off ebay a few years ago. The original battery was 12 volts but had been removed before I purchased it. There was indications of a small leak into the battery compartment. A battery pack up to 12 volts built from 4/3 cells will fit into the battery compartment. Below are a few pictures with the spare reflector assembly taken apart.

http://img134.imageshack.us/my.php?image=p1143802ar8.jpg
http://img99.imageshack.us/my.php?image=p1143803bc9.jpg

 

[Packhorse]

Looks do able to me

 

[steve6690]

Looks like a serious upgrade is needed. Those cable glands are most likely only rated to 5 bar which might explain the signs of water ingress. First step for me would be to replace them with a quality 10-bar brass gland such as a Pflicht Blue Globe. I'd also examine the cable for damage, and replace all the o rings.
As regards the light upgrade, I have no experience of the P7 so I can't comment on it. I prefer multiple led lights so I'd go with 5 x Cree R2 with DX 18.5mm reflectors driven from a boost driver such as a Shark. Should be good for around 1200 lumens, and it will give a narrow beam with plenty of spill. this will work fine with a 12v battery pack.
Or...if you don't mind a floody beam you could splash some cash and make a 3 x MC-E light with Ledil Boom SS reflectors driven by a buck driver such as the soon-to-be-released Taskled HipCC. Will give you over 2000 lumens..
It all depends on what you want from your light. Generally, a tighter beam is better for underwater use unless you only dive in very clear water. You need to decide what the runtime should be too. Once you decide on the characteristics of your light you will be able to choose your components.

hth

steve

 

[RWE]

OK, I believe that I have decided on a plan: a P7 module (http://www.dealextreme.com/details.dx/sku.14413) and 4 18650 rechargeable batteries. I have several additional questions:

1. On the P7 module, I assume the spring connects to the positive terminal. Where is the negative terminal? Is it the reflector or the copper base? If so, I will need to insulate the reflector from the aluminum light head since I intend to use in salt water. Is there an insulator material that has good thermal conduction characteristics?

2. If I use 4 18650 batteries, should I wire them for 3.7 volts or 7.4 volts? Is there a benefit or loss with the higher voltage?

Thanks for all your help,

 

[RWE]

OK, I believe that I have decided on a plan: a P7 module (http://www.dealextreme.com/details.dx/sku.14413) and 4 18650 rechargeable batteries. I have several additional questions:

1. On the P7 module, I assume the spring connects to the positive terminal. Where is the negative terminal? Is it the reflector or the copper base? If so, I will need to insulate the reflector from the aluminum light head since I intend to use in salt water. Is there an insulator material that has good thermal conduction characteristics?

2. If I use 4 18650 batteries, should I wire them for 3.7 volts or 7.4 volts? Is there a benefit or loss with the higher voltage?

Thanks for all your help,

Can someone answer the questions above?

Thanks,

 

[Packhorse]

I have not seen one in the flesh before but most drivers have the negative around the out side of the board. This one looks to be the same. It is probably in contact with the brass heat sink.
In regards to the battery configuration. It all depends on the driver really. If you choose 3.7v you may not get full brightness if the driver looses a few 10ths of a volt. Where if you run it at 7.4 volt it may be really inefficient.
Id try both and measure the voltage at the battery vs the voltage at the LED over the full discharge of a battery.
Personally I think you may be better off getting 8 amc 7135s (2800ma) to drive it off 3.7 volt. Or perhaps a 3 mode KD P7 driver at 7.4 volt.

 

[Scattergun]

If the module has a regular driverboard with negative around the rim, just remove the soldered bridge between rim and heatsink and isolate the driver from contact with the housing, then connect battery negative directly to the rim...

 

[rufusbduck]

Looks like a serious upgrade is needed. Those cable glands are most likely only rated to 5 bar which might explain the signs of water ingress. First step for me would be to replace them with a quality 10-bar brass gland such as a Pflicht Blue Globe. I'd also examine the cable for damage, and replace all the o rings.
As regards the light upgrade, I have no experience of the P7 so I can't comment on it. I prefer multiple led lights so I'd go with 5 x Cree R2 with DX 18.5mm reflectors driven from a boost driver such as a Shark. Should be good for around 1200 lumens, and it will give a narrow beam with plenty of spill. this will work fine with a 12v battery pack.
Or...if you don't mind a floody beam you could splash some cash and make a 3 x MC-E light with Ledil Boom SS reflectors driven by a buck driver such as the soon-to-be-released Taskled HipCC. Will give you over 2000 lumens..
It all depends on what you want from your light. Generally, a tighter beam is better for underwater use unless you only dive in very clear water. You need to decide what the runtime should be too. Once you decide on the characteristics of your light you will be able to choose your components.

hth

steve

Good stuff! I only disagree somewhat with regards to the tightness of the beam. I have a pelican kinglite as well as the saberlite and in both cases, the spot is so narrow as to be unusable at close range, i.e. the nooks and crannies of a coral reef. Both are headed to the mod-shop for surgery. I will be going for a 2'-3' spot at 6' for the saberlite(as opposed to the current 3" spot). It's better to see the fish than blind them or your dive buddies imo. I agree that a tight spot penetrates much better with less scatter but I think it's important to identify your needs an mod accordingly. Each to his/her own, eh?

p.s. throw that bit about blinding out the window, the kinglite will ONLY work underwater and will definitly be unsafe to look at.

 

[steve6690]

Agreed Rufus, although I did say "generally" a tighter beam is preferable. I am about to build 2 canister dive lights with slightly wider beams - around 13 degrees. One has 7 x xp-e r2's and the other an mce m' bin wg. I'm not convinced that a 6-degree spot is any real use except for signalling.

 

[HarryN]

I could not quite tell from the picture if the light body is plastic or Al. If it is plastic, you should probably limit the power level to the LED to about 5 ish watts, as plastic bodies are not particularly good thermal paths.

 

[RWE]

Responses to several items and a few additional questions:

• I plan on using the light for both critter spotting in holes/crevices and as a focus light for my camera in darker areas. A very narrow beam would not be best for the camera since it would sometimes show up in the picture when not overpowered by the underwater strobe. My previous Patco halogen light had about a 13 degree beam angle which was OK from a beam size perspective.
• The housing is aluminum. Is there a recommended thermal glue to enhance the heat dissipation to the housing? Is there a thermal glue that is not electrically conductive?
• Since the light will be used in sea water which has high electrical conductivity, the negative will have to be isolated from the housing and wired to the battery negative.

Thanks for all your help,