Minimalistic multichip DIY LED build

[Lassef]

I have learned by measuring that when a manufacturer says that FV is 30 - 36 V and maximum current is 3000 mA, for example, then FV at 3000 mA is just 36 V. If I use less current than 3000 mA then the FV is lower, but usually within range 30 - 36 V at normal current levels.

For drivers who have constant current, manufacturers are now starting to specifying a constant current region, ie within these voltage is the driver capable to keep the specified current.

Sincerely Lasse

 

[noplay180]

Katchupoy, So this led must me 2700ma? Also could you explain how to run tow of these leds in series on one driver. Thanks for all the help

 

[noplay180]

Thanks Lasse !

 

[Floyd R Turbo]

Katchupoy, So this led must me 2700ma? Also could you explain how to run tow of these leds in series on one driver. Thanks for all the help

You would need a driver capable of supplying at least 72V at a constant driver current of 3000mA, which would be 216W

 

[noplay180]

Thanks floyd I better understand. Wonder will I find a driver with those specs

 

[katchupoy]

Katchupoy, So this led must me 2700ma? Also could you explain how to run tow of these leds in series on one driver. Thanks for all the help

My BAD, it should be run two in parallel, at a lower wattage...
My apologies, I cannot edit my post anymore

 

[noplay180]

My BAD, it should be run two in parallel, at a lower wattage...
My apologies, I cannot edit my post anymore

Could dumb it down for me how would i calculated the voltage

 

[Floyd R Turbo]

This one is 240W, 36 VDC, 6.7A

http://www.mouser.com/ProductDetail...=Pc4kzEvJlcS6YT4fBn9zmd5kc5BQmGKr54aYgxIFQTY=

 

[Lassef]

This one is 240W, 36 VDC, 6.7A

http://www.mouser.com/ProductDetail...=Pc4kzEvJlcS6YT4fBn9zmd5kc5BQmGKr54aYgxIFQTY=

To which chip do you want to use that driver?

Sincerely Lasse

 

[katchupoy]

@NoPlay180

Not an expert but will try. The LED you indicated has this specs.

100w led:
temp color: 20000k
Vf:30-36V
If:1500mA (I dont know what this means)
LM:10000lm

Is that the current that it will run??? Then there is a conflict here?
36vdc X 1.5 = 54 watts??? So is it really a 100 watt or 54 watts???

Lets assume that it is 100 watts and it has a forward voltage of 36vdc,
then 100 / 36 = 2.7 amps. This is the current we are looking for.

Based on the driver you have given us.
HLG-100H-36B
Output(s) 36.0V @ 2.65A
Power 100 Watts

With 1 chip, this is very straight forward.

But with two chip in parallel. Since voltage does not add up and current does, you will need at least 5.4 amps. And since this driver can only support 2.65A + extra... then it means that you can run both chips at a lower current thus, lower wattage.

Actually to correct myself, it goes down to almost half the power. So like running 50 watt each per LED chip. One note, if you decided to go parallel, I must advice you to use fast blow fuse to protect the LEDs just in case one malfunction.

Hope this helps.

 

[Lassef]

EDIT: for above post, yes I wholeheartedly agree which is why I discuss things in terms of power, and leave resistance out of the equation completely. Not sure if I'm following your numbers above. But if I am right, when the current is 400mA the Vf is 2.8V. When the current is 3000mA the Vf is 3.3V. Vdrop is dependent on current, it's not the other way around...right? This of course is the danger of trying to use a CV driver

Its both way. if you use a constant voltage driver and change the voltage from 2.8 to 3.3 you rise the current in the LED from 400 mA to 3000 mA (if the driver i able to give 3000 mA). On the other hand - if you use a constant current driver and rise the current from 400 to 3000 mA the forward voltage will change from 2.8 to 3,3 V. Forward Voltage is tha voltage that you need to have the LED to light up. It is not the voltage that burn your LED up - its the current. Therefore its rather obvious why you shall use a constant current driver to power LED´s.

Sincerely Lasse

 

[Floyd R Turbo]

these are the specs the guy sent me for the
100w led:
temp color: 20000k
Vf:30-36V
If:1500mA
LM:10000lm

Katchupoy, So this led must me 2700ma? Also could you explain how to run tow of these leds in series on one driver. Thanks for all the help

I was saying that you could use this driver for 2 of these in parallel, per his question

 

[JohnnyAirtime]

At least in terms of 420 nm, it has significance for chlorophyll a, which has its blue absorption top right there. We must not fool ourselves by either PAR or lumen measurements. Certainly not Lumen. Lumen is just a measure of the radiation that is optimized for human color perception and has nothing to do with the biological importance to various plants and algae. PAR is a better method but most PAR meter does not consider the blue wavelengths real power in terms of photosynthesis. The human eye is poor on perceiving blue wavelengths actual radiation force as we often find that there is no "punch" in particular at wavelengths below 450 nm. For photosynthesis, however, the "the punch" just at these wavelengths.

According to fluorescence, probably no one knows the true biological function of the fluorescence of corals. In principle, fluorescence consists of a mechanism that takes high-energy short wavelengths and sends back a wavelength of less energy (longer wavelength than the incident light).

In this process, the coral get an energy boost - where does it go and what does it do - I do not know. However, fluorescence is extremely common among many corals. If a particular phenomenon is common in different organisms - then I allways suspect that it has a significant biological importance. What biological significance it has - I do not know, just that there are common causes me to suspect that it matters in a way or two.

LED technology offers us such a powerful tool so I do not think we understand the full extent yet. Just that we can put all the energy in a very narrow wavelength range (usually plus - minus 20 nm) allows us to use artificial light for production in a completely different way than when we work with full-spectrum sources. I show my table from my post 1082 again - because I think it is from here we must draw inspiration if we want to optimize for our corals as much as possible. And remember - just because the white light whash out the blue wavelengths of our vision - they are still there and can be used by various substances in photosynthesis. The white light is needed both for our aesthetic sense but also that it includes wavelengths that have biological purposes other than for photosynthesis.

Once again - for most corals - red wavelenghts probably is not so important becaus red wavelenghts disappear rather fast in the watercolumn in their natural habitants.

Sincererly Lasse

Good info... and, I guess without getting too scientific (I'm NOT an EE)... I use what works, and has worked for some time for all the corals in my 240... from SPS, to LPS, to ... well, you name it.

And, from what I've tested ... and used ... I've narrowed it down to the three colors I noted. I do know about other chip colors, and their benefits... (like Cholorphyl A and B) but I've never had coral die on me... due to the lack of, whatever the rest of the spectrum offers.

... So is adding ALL that wide of a spectrum necessary?! Who knows... it's too early to tell in our industry.

 

[ronreef]

Perfect.

Sincerely lasse

Thanks. I look forward to receiving the sample.

The 100W sample as I stated seems like a good mix.

 

[Lassef]

Good info... and, I guess without getting too scientific (I'm NOT an EE)... I use what works, and has worked for some time for all the corals in my 240... from SPS, to LPS, to ... well, you name it.

And, from what I've tested ... and used ... I've narrowed it down to the three colors I noted. I do know about other chip colors, and their benefits... (like Cholorphyl A and B) but I've never had coral die on me... due to the lack of, whatever the rest of the spectrum offers.

... So is adding ALL that wide of a spectrum necessary?! Who knows... it's too early to tell in our industry.

Photosynthesis is biological quantum mechanics. It needs a photon with the right energy, ie, wavelength, in order to function optimally. The various proteins involved in photosynthesis have different absorption peaks, and if we know them and have access to monochromatic light sources in precisely those wavelengths, one can get a lot more growth per inserted watt than using white light. By definition includes the white light almost all the visible wavelengths if it is from a full spectrum source. If you have access to white light containing all wavelengths in different concentrations, it is only in principle to increase the amount until our organisms get the quantity of the wavelengths they need. However, if we know the important wavelengths, we can by using a monochromatic source at the wavelengths increase the production as much as possible. We still need white light of the full spectral type, but we can put most of our use of electrical energy at the wavelengths our organisms need. LED technology provides both of these things. The white light from an LED is pretty close to a full spectrum and technology to produce monochromatic sources of different wavelengths is improving all the time.


The exact wavelengths of different corals can use as optimal I do not know but for me the wavelength 445 nm is quite interesting. 420 is also.

I do not think you need all the wavelengths mentioned in the passage quoted by me but I wanted to emphasize the difference between what we see and what actually happens.


Sincerely Lasse













Sincerely Lasse

 

[JohnnyAirtime]

Photosynthesis is biological quantum mechanics. It needs a photon with the right energy, ie, wavelength, in order to function optimally. The various proteins involved in photosynthesis have different absorption peaks, and if we know them and have access to monochromatic light sources in precisely those wavelengths, one can get a lot more growth per inserted watt than using white light. By definition includes the white light almost all the visible wavelengths if it is from a full spectrum source. If you have access to white light containing all wavelengths in different concentrations, it is only in principle to increase the amount until our organisms get the quantity of the wavelengths they need. However, if we know the important wavelengths, we can by using a monochromatic source at the wavelengths increase the production as much as possible. We still need white light of the full spectral type, but we can put most of our use of electrical energy at the wavelengths our organisms need. LED technology provides both of these things. The white light from an LED is pretty close to a full spectrum and technology to produce monochromatic sources of different wavelengths is improving all the time.


The exact wavelengths of different corals can use as optimal I do not know but for me the wavelength 445 nm is quite interesting. 420 is also.

I do not think you need all the wavelengths mentioned in the passage quoted by me but I wanted to emphasize the difference between what we see and what actually happens.


Sincerely Lasse

RIGHT... what you said! :fun5:

... Thanks a bunch. More good info!

 

[Floyd R Turbo]

Hopefully this isn't really off topic...trying to roll this all around in my head.

So I did a little looking around on ac-rc, they seem like they have a good selection of quality products, I know that Epistar is a leading manufacturer so I think I feel comfortable with their products. I seem to be gravitating toward the 20W chips, mainly because there is a decent variety and the price is good.

For the tank in question, which has a footprint of 66 x 21 and is 24? deep, with a few inches of sand and a LOT of LR, currently with 8x54W T5HO (416W) of light.

I had figured that I needed on the order of 100-120 3W stars, if I were going to go that route, and would likely get a 10" wide heat sink from heatsinkusa at a total cost for both of those at around $510-$570 <<corrected due to bad math LOL>> (not including drivers, fans, etc - just LEDs and heat sink. So the total wattage (based solely on rating) would be 300-360W.

Now from ac-rc, I like the 20W chips and the circular heat sinks. I figured that, just on an equivalent wattage basis calculation, that I would need 15-18 20W chips of various kinds. This would cost about $440-$524. Again, 300-360W LED, solely based on rating.

So at 120 3W stars vs 18 20W multichips, I <<corrected>> save about $45 w/r to only LEDs and heat sinks. I save $70 if I go with 15x 20W instead of 100 3W.

Now I haven't figured in a few things, obviously, like the necessary drivers, taking into account that I want to have everything PWM dimmable with as much control as possible, but just based on this rough calculation I have a few question, hopefully this is not too off topic and someone can chime in with their opinion:

The quantity calculation for the 20W chips was arrived at by simply taking the # of 3W chips I would need x3 and dividing that by 20. This would assume that in both instances, a 3W chip and a 20W chip are both driven at maximum current for an apples-to-apples comparison. Is my proposed 3W vs 20W quantity comparison valid, or will I need more or less 20W chips?

If the comparison is valid, then what is really the major advantage of using 20W chips over 3W chips? Aesthetics?

Are there other sellers of equally good product at lower prices that I should be considering?

If anyone can share their opinions or experiences with the ac-rc chips and/or other sellers' products, I would really appreciate hearing them

 

[Mike31154]

Thought I might chime in again here with an update to my 'risky' parallel constant voltage build using twenty seven 10 watt multichip LEDs. It's been running flawlessly since beginning of April. I use two 12 VDC power supplies, 250 watt & 150 watt, each on it's own timer, providing rudimentary dawn/dusk dimming by having them turn on/off at different times. The trim pot on each power supply is tweaked as low as possible so the supplies feed only around 10 VDC to the manual dimmers that further control voltage downstream. The 250 w powers two outer rails of my fixture & the 150 powers the center rail. Each rail has nine 10 watt LED multichips. Center has four 6-7000K whites & five blues. Each outer rail has five 10000K whites & four royal blues.

The only thing that has failed so far is one of the heatsink fans. Not sure how long the fan was out before I noticed & replaced it, but the LED suffered no ill effects. Each LED is on it's own heatsink with fan. I figure the heatsink itself plus the aluminum rails it's mounted on took up the slack the fan no longer provided. I have yet to do current measurements on each individual LED, I'm trusting the manufacturing process to be sufficiently precise that all the LEDs run at 'close enough' to the proper current within their rated forward voltage range. I run the LEDs at less than the max fwd voltage & still get sufficient light for my livestock. The lower fwd voltage provides a safety buffer in case an LED burns out, which would potentially increase current delivered to the remaining diodes. Highest I've run them at for any length of time is 7 volts. The rated max fwd voltage for the LEDs I have is between 9-12 volts, depending on the LED color.

Here's a photo of the power supply/dimmer set up as it stands now. I use two voltmeters to monitor each color of LED using two DPDT switches. The upper voltmeter displays voltage delivered to royal blue & 10000K LEDs controlled by the dimmers on the left & the lower VM is for the 6-7000K whites & blues controlled by dimmers on the right.

About the only change I'm considering is to run the heatsink fans at the rated 12 volts. When I soldered up the LEDs I decided to hook the heatsink fan leads directly to the LED terminals. Consequently the fans are in effect parallel with the LEDs & run at a lower than designed speed. Most of them need a kick start via my finger in the morning since I start the LEDs at 4 volts. In a way I may have stumbled upon another safety buffer by having the fans wired to the LEDs, in that if a LED fails, the fan would take any excess current. This theory has yet to be tested though, since none of the LEDs have burned out to date. I've been putting off the mod since it would mean cutting the +- leads off 27 fans & rewiring them. The fan wires are a very small gauge & tricky to work with.

 

[007Bond]

Question so I understand, If I buy a 100w AC-RC chip which is rated at 32-36 fv and 7a max which can put out 252w and run it with a Meanwell HLG 240H-36B driver that is rated 36V and 6.7A, and I lower the 1-10v dimming signal to the driver which will dim the led to say 100w of output, Is the dimming actually lowering the current that the driver is providing to the led? I want the versatility to run the chip at higher wattage if needed, but also lower wattage for extended led life. So I want to make sure I get a driver that can run the chip to the higher end if needed.---Rick

 

[Floyd R Turbo]

Question so I understand, If I buy a 100w AC-RC chip which is rated at 32-36 fv and 7a max which can put out 252w and run it with a Meanwell HLG 240H-36B driver that is rated 36V and 6.7A, and I lower the 1-10v dimming signal to the driver which will dim the led to say 100w of output, Is the dimming actually lowering the current that the driver is providing to the led? I want the versatility to run the chip at higher wattage if needed, but also lower wattage for extended led life. So I want to make sure I get a driver that can run the chip to the higher end if needed.---Rick

I guess it depends on how you dim it. Analog dimming would lower the current, PWM dimming would drive it at full current but turn it on and off so fast that it would look like it was dimmer (to us). I believe either way, you would want the cooling system adequate to handle 100% all the time and you should be fine.