New Member – Project Recommendations Needed!

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Natchamp

Newly Enlightened
Joined
Dec 9, 2011
Messages
9
Gents,


I need some guidance and education for an LED project I’m working on. I’m definitely not an electrical engineer but I love to learn about things. I’ve been doing a huge amount of reading trying to learn everything I can and my head is about to explode from too much information! So, it’s time to get some advice on whether I’m pointed in the right direction.


Project: make some underwater LED lights for my boat. The plan is to have probably two fixtures, one on each side of the transom (rear) of the boat. Underwater LED’s are available but they can get very spendy. Since I’m naturally a diy’er and I have CNC equipment I can make the housings myself. The fixtures will be under water so heat dissipation should be no problem with aluminum housings.


Output: I would like to have each of the fixtures produce at least 2,000 lumins preferably. There are ones available to buy at this level (>5,000 lms) so I know it can be done. I really want the highest lumins, brightest lights, I can make while still being reasonable in cost and current draw. The color needs to be green. I would really like dimming capability but if it adds too much complexity maybe some simple levels of power/brightness.


Considerations: I would really like the current draw for each fixture be no more than 3 amps, so if I had two fixtures the total draw of the lights would be 6 amps. From my reading it looks like I can drive them with my standard 12v system which wouldn’t work well because the amp draw would be too much. I could use a DC/DC step up system to up my voltage and reduce the current. Or I could possible use the 110 VAC system on the boat to really lower the current draw. The only drawback to an AC setup is I could only run the lights when at the dock or when the generator is running.


LED’s: I’ve looked at several emitters like Cree’s X-Lamp, BridgeLux, Osram, and Luminus. So far I’ve narrowed it down to the SST-90 from Luminous. Am I on the right track here? One slight wrinkle is the need for green color so please keep that in mind.


Drivers: Depending on what the best approach you guys think is between 12v, stepped up 12v, or AC the following are some potential solutions for drivers:


http://www.candlepowerforums.com/vb/showthread.php?327770-100-watt-CC-LED-Driver-for-12
http://www.candlepowerforums.com/vb...able-10A-linear-LED-driver-limited-quantities
http://www.candlepowerforums.com/vb/showthread.php?321013-DC-DC-70-Watt-LED-Driver
http://www.candlepowerforums.com/vb...icient-5A-9A-Buck-Converter-for-SST-50-SST-90
http://www.taskled.com/

So, I’d really like to get your opinions on what’s the best approach for me to take? Are there other LED’s I should be looking at? Given my current draw requirements do I have to use a stepped up DC or AC driver? Any guidance and information is greatly appreciated!
 
Last edited:
Natchamp said:
Gents,

Project: make some underwater LED lights for my boat. The plan is to have probably two fixtures, one on each side of the transom (rear) of the boat. Underwater LED’s are available but they can get very spendy. Since I’m naturally a diy’er and I have CNC equipment I can make the housings myself. The fixtures will be under water so heat dissipation should be no problem with aluminum housings.
Click to expand...

Be sure to look at the diving forum for waterproofing ideas.

Output: I would like to have each of the fixtures produce at least 2,000 lumins preferably. There are ones available to buy at this level (>5,000 lms) so I know it can be done. I really want the highest lumins, brightest lights, I can make while still being reasonable in cost and current draw. The color needs to be green. I would really like dimming capability but if it adds too much complexity maybe some simple levels of power/brightness.
Click to expand...

Assumption here is that your looking for a lot of spill and little to no spot? IE Flood lights


Considerations: I would really like the current draw for each fixture be no more than 3 amps, so if I had two fixtures the total draw of the lights would be 6 amps. From my reading it looks like I can drive them with my standard 12v system which wouldn’t work well because the amp draw would be too much. I could use a DC/DC step up system to up my voltage and reduce the current. Or I could possible use the 110 VAC system on the boat to really lower the current draw. The only drawback to an AC setup is I could only run the lights when at the dock or when the generator is running.
Click to expand...

3amps off your boat battery wont be an issue with a good driver

LED’s: I’ve looked at several emitters like Cree’s X-Lamp, BridgeLux, Osram, and Luminus. So far I’ve narrowed it down to the SST-90 from Luminous. Am I on the right track here? One slight wrinkle is the need for green color so please keep that in mind.


Drivers: Depending on what the best approach you guys think is between 12v, stepped up 12v, or AC the following are some potential solutions for drivers:


http://www.candlepowerforums.com/vb/showthread.php?327770-100-watt-CC-LED-Driver-for-12
http://www.candlepowerforums.com/vb...able-10A-linear-LED-driver-limited-quantities
http://www.candlepowerforums.com/vb/showthread.php?321013-DC-DC-70-Watt-LED-Driver
http://www.candlepowerforums.com/vb...icient-5A-9A-Buck-Converter-for-SST-50-SST-90
http://www.taskled.com/

So, I’d really like to get your opinions on what’s the best approach for me to take? Are there other LED’s I should be looking at? Given my current draw requirements do I have to use a stepped up DC or AC driver? Any guidance and information is greatly appreciated!
Click to expand...


Lots of choices for sure...

Personally I'd go with a two 3 x Cree XM-L's from cutter.com.au and a couple LFlex drivers from taskled.com and call it a day.
This would give you up to 3000 Lumens at 3Amps per light head and 5 selectable levels of output.
Designed them like a canister light and you could even use them for diving ;-)

As to coloring the light... filters are cheap
 
My idea:

Use Cree XP-G around 10 LEDs and decent driver to suit with your input voltage.

Construct housing yourself (some commercially available housing can be modified to waterproof. use silicone adhesives, epoxies etc..)
 
David_Campen said:
I am using the LEDengin LZ4-4 blue and reds to construct plant growth lights. Their LZ4-40G100 puts out 525 nm green. Typical values for one of these emitter packages is 600 lumen at 15V forward voltage and 1 amp. So if you took 4 of these and wired them in series-parallel you would get 2400 lumens at 30V and 2A.
http://www.ledengin.com/products/emitters#LZ4
http://www.candlepowerforums.com/vb...8-LEDEngin-10-watt-15-watt-Information-thread
Click to expand...

David, Thanks for the info. If I'm understanding the specs correctly, I would need to use some kind of step up DC transformer? I see the min Vf is 13v and the Vf is 14.4 at 700ma and Vf 15.0 at 1,000ma.

Also, I think I don't understand a fundamental aspect of current calculations. If each emitter uses 1 amp and I use 4 wouldn't the total current draw be 4 amps? My readings so far have told me that usually these high power emitters should be in series. Does a series type of circuit have a different "rule" when calculating the total amp draw? Sorry to be such a newbie at this stuff!
 
Codiak said:
Be sure to look at the diving forum for waterproofing ideas.

Assumption here is that your looking for a lot of spill and little to no spot? IE Flood lights

Personally I'd go with a two 3 x Cree XM-L's from cutter.com.au and a couple LFlex drivers from taskled.com and call it a day.
This would give you up to 3000 Lumens at 3Amps per light head and 5 selectable levels of output.
Designed them like a canister light and you could even use them for diving ;-)

As to coloring the light... filters are cheap
Click to expand...

I'll be sure to check out the diving forum, thanks!

Yes, I need a flood, wide-beam, not a spot.

Looking at the XPE's instead because I don't want to use a filter I see the following specs. Vf of 3.4 volts, 100lm at 350ma and 216lm at 1,000ma. However, in their specs it talks about "groups" but I don't see anywhere the definitions of what a "group" is for them. Anyways, if each light had 3 of the XPE's then at the max of 1,000ma I would only have 648lms the way I calc it. Somehow I think I'm not understanding the basic calculations as I mentioned in the post above. I think I need to learn that first!

I found a reference in a thread that I think corrects my understanding but please tell me if I'm wrong.

My current understanding - If you wire the emitters in series the total amps of the circiut is the value of a single emitter and the voltage draw is the sum of all the Vf's. So, let's assume a series circuit of 3 emitters having a Vf of 3.4 and a max of 1,000ma. That circuit would draw only 1,000ma but you would need a voltage of at least 10.2 volts.

Is this correct? If so, then does this mean I could potentially have a single light fixture with 3 paralleled circuits each containing a series-string of 3 emitters and the calc would be a total draw of 3 amps and still have a total voltage draw of only 10.2 volts? This would give me 9 emitters and a total lms of 1,944. The cost of this would start to add up with all of those LED's. Please forgive me if I'm all wrong here but I need to learn this because it's so fundamental.
 
The housing can be just a cut down mag with oversized orings.


Lots and lots of options
 
ok, so I've done a bunch of reading and I think I got a much better understanding of the calcs involved with series vs parallel circuits. I've also been looking at the Bridgelux emitters. What I need to narrow in on is a cost effective driver that can boost up my 12v to @ 30v while providing constant current regulation. Any suggestions?
 
David_Campen said:
I am using the LEDengin LZ4-4 blue and reds to construct plant growth lights. Their LZ4-40G100 puts out 525 nm green. Typical values for one of these emitter packages is 600 lumen at 15V forward voltage and 1 amp. So if you took 4 of these and wired them in series-parallel you would get 2400 lumens at 30V and 2A.
http://www.ledengin.com/products/emitters#LZ4
http://www.candlepowerforums.com/vb...8-LEDEngin-10-watt-15-watt-Information-thread
Click to expand...

I would suggest that you get a 12V DC to 115V AC converter separately from the LED drivers. These converters are not expensive and then you have more options when looking for LED drivers.

For the LED arrangement that I suggested a Meanwell LPC-60-1750 should work.
http://www.meanwell.com/search/lpc-60/lpc-60-spec.pdf
This would give you 1750 mA to split between the parallel strings

Note that when you wire LEDs in parallel, while the current is split amongst the parallel strings it is not necessarily divided equally. It depends on how the Vf vs. current characteristics match up.

Here is an inexpensive DC/AC converter:
http://www.google.com/products/cata...LnmTs_zNafq0gHR3bHwCQ&sqi=2&ved=0CJ8BEPMCMAQ#
 
Natchamp said:
...
Looking at the XPE's instead because I don't want to use a filter I see the following specs. Vf of 3.4 volts, 100lm at 350ma and 216lm at 1,000ma. However, in their specs it talks about "groups" but I don't see anywhere the definitions of what a "group" is for them. Anyways, if each light had 3 of the XPE's then at the max of 1,000ma I would only have 648lms the way I calc it. Somehow I think I'm not understanding the basic calculations as I mentioned in the post above. I think I need to learn that first!

My current understanding - If you wire the emitters in series the total amps of the circiut is the value of a single emitter and the voltage draw is the sum of all the Vf's. So, let's assume a series circuit of 3 emitters having a Vf of 3.4 and a max of 1,000ma. That circuit would draw only 1,000ma but you would need a voltage of at least 10.2 volts.

Is this correct? If so, then does this mean I could potentially have a single light fixture with 3 paralleled circuits each containing a series-string of 3 emitters and the calc would be a total draw of 3 amps and still have a total voltage draw of only 10.2 volts? This would give me 9 emitters and a total lms of 1,944. The cost of this would start to add up with all of those LED's. Please forgive me if I'm all wrong here but I need to learn this because it's so fundamental.
Click to expand...
By groups they are saying that these LEDs range from 75 to 100 lumen at 350 ma. Sometimes you can get the LEDs sorted into these groups but more likely you will get a random distribution of performance characteristics or even get LEDs that have had the highest bins (groups) pulled out for sale at a premium price while you get the lower performing LEDs.
 
Hi David,

Thanks for all the info. I'm currently leaning towards white emitters and using a filter for the green color. I'm aware that I'll loose some lumin output using a filter but the selection of white emitters is so much larger. And when I look at the lumins/watt ratios I think the output loss is more than compensated for.

As for the driver, I'm really trying to avoid using AC as the power source. The only problem is finding a DC boost driver with 3 amps capacity. I came across these today:
http://www.xicato.com/downloads/XIC8193_XLM_80_Linear_Spec.pdf and they look pretty interesting. These would allow me to use a more-comon boost driver of 1.5 amps. But these Xicato's aren't available through the normal distributor channels.

Almost hate to bring this up, but what's the deal with all the Chinese LED's? I'm assuming the specs are greatly exaggerated? Below are some examples of what I'm referring to. They spec out 4,000 lms at 30-35v and only 1.5amps.

http://www.ebay.com/itm/1PC-50W-Whi...424?pt=LH_DefaultDomain_0&hash=item5d313d0e20
http://www.ebay.com/itm/1pcs-50W-Su...432?pt=LH_DefaultDomain_0&hash=item3cbebeca50
 
Natchamp said:
ok, so I've done a bunch of reading and I think I got a much better understanding of the calcs involved with series vs parallel circuits. I've also been looking at the Bridgelux emitters. What I need to narrow in on is a cost effective driver that can boost up my 12v to @ 30v while providing constant current regulation. Any suggestions?
Click to expand...

Check the specs on the MaxFlex from taskled.com
 
I don’t think using filter is a good idea. You will use only small fraction of light emitted by white LED.

If you look at white LED spec for spectral power distribution (see color graph in Xicato spec you linked) you can see that green is only a little part (as are the other colors). White LED will use more power and emit less "green" lumens.

You want about 3A out of 12V DC source. So, you have about 36W to play with.
Decision to go with high current or high voltage will probably boil down to green LEDs availability.

Green SST-90 will call for high current driver. This one at Mouser will give you about 1000lm driven at 5A. I don’t know if you can find them mounted on board. Plying with bare emitter may too much hassle. You could connect two in series and use TaskLed H6Flex or H6CC or Der Wichtel (5A version) driver. They are all buck drivers and will convert your 12V supply to required ~7.4V (two LEDs in series each 3.7V according to spec). H6Flex has microprocessor on it and allows you selecting modes with switch. It also has some extra features like thermal protection and battery warning but these are not important in your case. H6CC and Der Witchtel (adjustable version) may be dimmed using external potentiometer.
About 7.4 V on LEDs, 5A current is about 37W. Given driver efficiency about 90-95% it is about 40W from power supply. Little more than your 36W but you can go with little less than 5A if this is too much.

Going with smaller LEDs you will need much more of them. Each string of LEDs should have its own driver (driving parallel LEDs from one constant current source is not recommended because current in each string may differ a lot).
For driving that you need boost driver. Up to 7 LEDs (green have little higher Vf than white LEDs) MaxFlex is good. Higher you could use Hyperboost. MaxFlex has the same UI as H6Flex (as all Flex drivers from TaskLed). Hyperboost has trimpot that sets max current (up to 1.4A) and may be wired to external pot for dimming.
7 LEDs on board may be found here (you can get 50 degree lens for it if you decide that 120 degree beam out of LED itself is too much flood). Easy to work with, solder pads on board to create series connection, connect MaxFlex (or some other boost driver), switch and you good to go. This will not give you 2000lm though.
You can wire two of these in series and use Hyperboost for higher output. You would want to set driver for 750mA output in that case. 14 LEDs will give you about 48Vf, so with 750mA you have 36W you wanted. And rated output at that current should be ~2200lm.
 
Last edited:
arek98,

Now that is a bunch of good info, much appreciated! I think some of this is starting to sink in, thanks to all.

I think the first thing I need to do is decide on the white w/filter versus green emitter. I read a bunch of threads on using a filter but couldn't find anything that specified exactly how much lums you loose as I suppose that is so application specific. Let me see if I understand it correctly. The way I understand it now is if I look at the color spectrum output of the led (like the picture below) and I quantify the percentage of output relative to the specific color I need, that ratio/percentage of output relative to the total output is what I would get. For my example in the below exercise would be approximately: For green I need somewhere in the 520-550 range. Let's say that portion of the output is approximately 10%. Lets just say the total lum output for that emitter is 1,000 lums. So, only 10% (or 100lms) would be the output when using a green (520-550) filter?

led_1.jpg

If my understanding is now correct I see what you mean. Actually I hope I'm wrong cause that really limits my emitter choices!
 
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