I need help for 12vdc boat searchlight....

[onetrickpony]

Hi, just looking for the best way to drive a light I'm building for my wife's uncle. It will be powered off of the 12v lead acid battery that starts up the motor and powers a few other electronic devices.

I have two ideas, tell me what you think:

1. Single sst-90, either direct drive with resistor or underdriven by a 6.5A 5 mode driver I have lying around.

2. 4 (or more) XML's direct drive with resistor or with a driver. I like simple and durable.

Here's the rub, I have a really nice improvised heat sink, some 75 mm glass aspheric lenses lying around (probably going to use just one) and I really don't want to go crazy buying parts, so cheap is very good.

I have a theory in the back of my head that running more LED's at the current that gives the best lumens per watt to achieve the desired brightness is better than running one LED at a much higher current. First off, longer run time off of the 12 v lead acid battery, and second, way less heat and damage to the components.

If anyone has done something like this successfully, what did you do?


EDIT: PS, I really want this thing to be amazingly bright, this guy has helped me out a lot over the years, and if the only way to do it right ends up being kinda expensive, that's ok too. I'm looking for between 2 to 5 thousand lumens, and the ability to light something up as far away as possible, I can probably come up with a way to focus the lens from spot to flood so it's more about the raw lumen output.

One more question, how much efficiency will be lost if the lens is out of focus or if I go with multiple led's under a single lens, meaning that only one is at the focal point of the lens?

Thanks again....

 

[VidPro]

with aspherical type of optical lens it is probably best to have the light emitting parts to be in One place. if you put multiples then you need to have multiple optical convergances of the seperated light items. even a quad emitter suffers a small ammount from the seperation of the light emission. so if the light emitter things are way seperated then you would need a special lens or multiple lenses that re-direct the output , or you will have a pretty big seperation that will mess with viewing.
you will have 3 seperated balls of light , with a well focused single aspherical projection , when you have 3 emitter items that are seperated from eachother. it is pretty useless except for 3 eyed aliens:huh:

indeed running a huge "ammount of semiconductor gates" at a lower rate is better efficency, i dont find that it makes as Much difference for those tiny gate items to be seperated except for the cooling aspect of it. As if anyone is going to understand that :-)
Meaning if you have a huge Line of diode gates run at a prime currents for each gate, that is just as efficent as having a tight bundle of tiny little gates run at prime currents for them. you just have to find a way to cool them better when they are all crammed together. (and the phosphors issue also)

when resister or direct driving, 4 series sets of white led items has an interesting "pattern" when the battery is well charged, alternator running and all, it is very bright and "tuned properly" with Good quality regulation on the engine alternator regulator stuff, it works good.
vrses "properly" current controlling the items.
AND
When the battery is not being charged, it kinda goes into Medium drive, and when the battery does not have a good charge, the light will be Low, and the engine will still start like 2 WEEKS later if the light was left on. :-)
I use that Oddball method on my car, which no normal person would enjoy the change in output, or even understand its "feature" of being able to start the car even if the light has been left on. Simple and effective, but only when understood.
they call it unregulated , I call it "self-regulated" as the battery power is less so to is the light less. works that way with my solar system too, which can hold out for weeks with no sun.

Switching from 4 to 3 in parellel, and putting in more resistance, would maintain MUCH more stable current levels, with the resistered method , and would be an acceptable method for those normal people :-)
That is not going to be easy to do with a Quad die item, so that leaves 2x2 as possible too for similar current levels at the varied voltages.

If it is going to a normal human being, and it must have huge exacting output at all times, then it will probably have to have a proper current control regulation driver thing on it, because they may attempt to use it where it was not designed and all.

There is already an efficency drop by using an aspheric to begin with, as much of the side light is not culminated to the front at all, Optics will try and pick up the side light and redirect it forward. Depending on the optics and the aspheric lens , would depend on the concentration of light to a single point. adding in a reflector behind optics works, but behnd aspheric is would have to be very specifically designed for aspehric. When you put a "normal" reflector back into an asperic system, the "saved" lumens just go willy nilly all over the place, could be rings, or just spill.

the proper diffusions mixing up the emitter lights together prior to projecting it, is possible , but the losses from even the best diffusion (laser cut stuff) or from primo linearized diffusions is high.

focus with aspehrical lensing is critical, again dependind on the lens itself, a DE-focused aspheric can have a enviable beam of perfecally round iluminations , that can turn a "spot" light into the most amazing circle of iluminations that few reflectors are so well designed to be able to do that. having the focus being adjustable IMO adds more value to a light item than some of the excessivly bright stuff does.

The aspherics often work best with the bulging side facing out of the light, without a Cover over that bulging bright honk of glass sticking out the front, the light spashes back into the user so badly as to close the iris of the eye down (as any spill light can). If all culminated light is directed ONLY at the target and not the person holding the light, and there is zero spill , then the percieved brightness, and ability to see far away is enhnaced greatly. so try not to spill onto your user. (which only leaves the fog problems :-)

more than one modder has put together many many optics operated led items together in a converged system (aim each led and optics) and the results are amazing.

 

[onetrickpony]

Holy crap that was a fantastic answer.

One more question, if I go with the sst-90 and resistor, could I also put a few smaller led's around it to get closer to 12v even though they would be drawing far less current? That sounds like it wouldn't work to me, but I don't have the electronic engineering science to back it up....

I think I'm going to take your advice about the optics, possibly with a large aluminum reflector. The reason I was thinking of using the aspheric lens is that I already have it, and it would be easy to seal up for salt water protection. I'll probably just pick up flat glass lens.

I like the idea of the motor still being able to start should the light be left on, especially if there are kids (and adults) constantly playing with the light. I'll just have to explain the "pattern" when I give him the light. It's bad if your car won't start, it's far worse if your out on the ocean, I think he'll like the idea.

Thank you again, you have no idea how great it is to be able to have this kind of information. I have no desire to "guess and check" three thousand times to get this thing going, especially with summer right around the corner.

 

[VidPro]

uhh, you still have to check and check and test under different voltages :-) If the current is to high to the leds, they can be burned out, both immediataly and over time gates can fail, so without knowing the current flow through it, you could make something that will be at 50% output in 300 hours. so you still gotta do lotsa checking. you certannly have to check more than if you used proper current control methods.

The Voltage of the LEDS can possibly change, older leds and smaller leds showed this phenomena more. any burnt gates, or increases in the passage of current because of changes in the led, or temperatures will change EVERYTHING. that is another reason for current controls.

I do this very often, but you gotta know there are many ramifications.

yes , you can use other arrays of different leds to reach voltages, as long as Again you understand that " the led likes to be driven at very specific currents, and as the voltages Vary , the current changes like Night & Day"
and
any current flow through any of the curcuits would have to be low enough that the smallest item in the current flow can handle the current passing through it .

The smallest of resitances will vary the voltages quite a bit, so even things like the length of wire itself would vary the voltage and therfore the current flow , greatly.

Example:
In one "voltage array" set i have been running for years, it uses 3x3 1W leds, in seires with a single 3W led.
The Only reason i did or would use a different led in ANY set, was because i didnt want to put a power waster in, and instead use a light item as the power waster.
I had increased the voltage at the input, so i just tacked in more "diodes" to get to the correct voltage.
normally it is far better to have any series or parelell arrays of any sort be HIGHLY matched, and all SAME, and run lower than Max, well cooled, and tested heavily.

|----|>-------|>-------|>-----|
|----|>-------|>-------|>-----|
|----|>-------|>-------|>-----|

had this configuration being run at around ~11 volts with adjustable regulator for voltage only
power input was from a 12V transformer peaks at ~15V
after dumping the (linear) regulation, because it heated up to much for the container it was in . . .

|----|>-------|>-------|>-----|
|----|>-------|>-------|>-----|
|----|>-------|>-------|>-----|------|>-3W-----|

I just tossed in another "diode" LED to match the voltage
still running it is going for more years than i can remember, must be at about 10years .

ALWAYS run lower than max specs, when doing this , and checked everyonce in a while to see it it is changing at all, because again it is not current controlled.
http://www.candlepowerforums.com/vb/showthread.php?174996-The-Sun-80Watt-configurable-area-light
here is a 170Volt "voltage driven" mega series parrelel configuration, that uses no regulation, only voltage matching, and specifically well cooled, and specifically under driven. been running now for . . . that was 2007. but it is often dimmed also.

 

[onetrickpony]

That is a really cool project, too bad a lighting design company hasn't hired you, we'd all have nicer fixtures in our homes.

I was thinking the same thing about using led's instead of other forms of resistance because at least that much more of the energy would be used to produce light instead of heat. Unfortunately, I'd have to come up with somewhere between 20 and 30 watts of current consumption from my other led's to match the current draw of the single sst-90, depending on how hard it will be driven. So, I could have 10 3 watt leds running parallel then in series to the sst-90, or I could just use a huge resistor to get to 12 volts. I kind of want to do the multiple led's, though I guess I could use a combination of the two. In any case, you have been very helpful. I'll post pictures of the build when it starts coming together. Thank you again.

 

[BVH]

EDIT: PS, I really want this thing to be amazingly bright, this guy has helped me out a lot over the years, and if the only way to do it right ends up being kinda expensive, that's ok too. I'm looking for between 2 to 5 thousand lumens, and the ability to light something up as far away as possible, I can probably come up with a way to focus the lens from spot to flood so it's more about the raw lumen output.



Thanks again....

Just checking even though you are talking LED here. An LED light is never going to throw like a 35 to 50 watt HID. 3,000 Lumens is coasting for a 35 Watt and power consumption will probably be lower also. A lot of flood Lumens gets lost on a body of water real fast.

 

[onetrickpony]

Just checking even though you are talking LED here. An LED light is never going to throw like a 35 to 50 watt HID. 3,000 Lumens is coasting for a 35 Watt and power consumption will probably be lower also. A lot of flood Lumens gets lost on a body of water real fast.

I have absolutely no experience with HID, could you point me to a good starting point for info? I'd be willing to consider it, with the caveat that I already have a bunch of led related stuff, so I would be pretty much starting from scratch....

 

[glockboy]

Try the Stanley HID Spotlight.

 

[BVH]

BatteryJunction.com (MattK here on CPF) his Titanium line of lights. The N30 (Nimh) or L35 (Li-Ion, more expensive), both about 3000 Lumens with good throw and about 80 to 90 minutes minutes run time IIRC. IIRC, you can buy a DC adapter to run the L35 off a cig lighter adapter.

I think this is our only HID forum education thread:

http://www.candlepowerforums.com/vb/showthread.php?133415-Spotlights-amp-HID-Threads-of-Interest

As Glock says, the Stanley is a darn good deal and it will run off the internal battery and the included Cig lighter DC power cord powered form the boat battery.

 

[onetrickpony]

Well, I took some time yesterday and today to look at HID, and all I can say is WOW. I'm still a big fan of led's, but HID's fill this application sooooo much better. I'm tempted to buy one of those Stanley's and take out all the parts and mount them in a waterproof case.... Anyhoo, I think I'm going to build the led version with the sst-90 and a few LM317 voltage regulators, then keep it and give something like the modified Stanley to my wife's uncle.

I found a cool page about circuit designs using these regulators, and I bought a pack of 25 of them a while ago and never used them. The ones I have are rated at three amps. Can anyone explain to me how to use them in parallel to get 6 to 9 amps (I'd rather 6 or 7, I want this thing to LAST).

Here's the link to the page I mentioned: http://www.onsemi.com/pub_link/Collateral/AND8109-D.PDF

I'm not sure if hotlinks are ok, so if not, mods please let me know and I won't do it again!!!

 

[Sway]

Get a LightForce ML 240 Blitz spotlight with battery clamps or cigarette lighter plug and call it a day, they are water resistant, designed for marine use and will float when it goes overboard. They will handle the rough and tumble boat life and have very good throw (reach/return) what ever you want to call it and hold their own against small reflector HID lights.

Everything else discussed is not practical for use on the water because of the environment and will sink to the bottom like a rock.

Overboard = light gone, pick the right tool for the job :)

LightForce Marine Lights

This site has good prices

Later
Kelly

 

[onetrickpony]

My original goal with this project was to make a light that IS in fact suitable for marine use, aka waterproof and very durable, and that would be hard mounted to the boat with the option of removal offshore to prevent theft or other damage. I'm sort of kidding when I say I'm going to give him the Stanley HID, although I would if I put the guts in a more suitable housing.

Part of the reason for this project is the fun involved, and also the fact that having something that someone else built for you is just cool. However, I've had conversations with my wife about my fears in giving someone something that they may very well rely on in a dangerous situation out on the ocean, especially if the item is fairly untested/unproven.

Thank you for the link to the Lightforce page, I'm impressed with their product and their prices. If the end result of what I'm building ends up being unsuitable or unreliable, I would definitely point him in that direction.

You also bring up a good point about the possibility of losing the light to the briny deep. Keep in mind that this light will have no internal power source, though. I could easily integrate a stainless cable (or chain, etc.) to the power cord and bolt it to the mount on the boat. The purpose of the light is limited to long distance spotting, it will not be used for area lighting or for general around the boat duty. I'm thinking it will probably be mounted to the boat and left there until the boat is docked again.

 

[HarryN]

Thanks for the links sway.