# Will this setup work with this driver?



## mnm99 (Dec 11, 2014)

I had a little change of plans in the type of led I am using. I was wondering if using the this Flexblock with these led's in the series I have noted will work ok? I just don't want to burn them out on my first try. Thanks

*Flex block 700ma in 48V boost mode.* http://www.luxdrive.com/products/flexblock-a011/

*4 - Philips Luxeon M ROYAL BLUE 12 Watt LEDs* = Forward Voltage is 11.00V @ 700ma, 11.40V @ 1,000ma


*1 - Philips Luxeon ES ROYAL BLUE 3 Watt LEDs* = Forward Voltage is 2.75V @ 350ma, 2.95 @ 700ma, 3.00V @ 1,000ma

In this sequence ----12w + 12w + 3w + 12w + 12w


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## evilc66 (Dec 11, 2014)

The sequence doesn't matter. All you need to worry about is if the total forward voltage is within the limits of the driver, which it seems to be.


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## mds82 (Dec 11, 2014)

So you want to run all 5 LED's in the same string? That wont work with 1 driver. If you have all 5 LED's in series they they all all get the same mA which is 700mA. I would recommend running the 4 Luxeon M's with 1 flex block and then the Royal Blue from a seperate driver that is 350mA, such as the buckblock drier.


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## mnm99 (Dec 11, 2014)

Why cant I add the ES? it will allow 700ma also just like the M's ?? The M's are at 11.0V each and the ES is at 2.95V. 11v x 4 = 44 + 2.95v = 46.95v. The flexblock puts out 48v. ??


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## poolman966554 (Dec 11, 2014)

mnm99 said:


> Why cant I add the ES? it will allow 700ma also just like the M's ?? The M's are at 11.0V each and the ES is at 2.95V. 11v x 4 = 44 + 2.95v = 46.95v. The flexblock puts out 48v. ??



EDIT: Re-read post, and agree with evilc66.


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## evilc66 (Dec 12, 2014)

mds82 said:


> So you want to run all 5 LED's in the same string? That wont work with 1 driver. If you have all 5 LED's in series they they all all get the same mA which is 700mA. I would recommend running the 4 Luxeon M's with 1 flex block and then the Royal Blue from a seperate driver that is 350mA, such as the buckblock drier.



He never said he was intending to run the Rebel ES at 350mA. He just posted the vf at given currents (notice the vf listed at 350mA, 700mA, and 1000mA). The Flex Block he listed is a 700mA version, so all LEDs connected to it would run at 700mA, which is well within the specs of both LEDs.


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## mnm99 (Dec 13, 2014)

One more question. I also have a bunch of other led's. Should I be OK running these of the same flex block? The voltage only adds up to around 43.2v and the block puts out 48v

12 - 3w led in series. Says Forward Voltage :3.5V~4.0V Forward Current:700mA, but another spec says *Forward Voltage (VF) *MIN/TYP 3.2-3.6v. *Reverse Current(IR)
VR=5V
(uA) 100

EDIT...I found this in another thread. If this is the way it works I understand now. Thanks

*Led power (P) = The voltage drop across the LED (V) * The current passing through the LED (I)

Lets use some round numbers for an example.. Lets say you have 4 LED's.. each is rated for 10 volts and 1 amp.. so each led is theoretically 10 watts.. 
You hook up all four in series with a constant current power supply that delivers up to 48 volts at 1 amp.. 
The power supply will adjust the voltage to 40 volts because that is what it will theoretically take to "push" the 1 amp of current through.. Current will remain the same at 1 amp through all four LED's. In any series circuit, current is always the same.

1st LED: 40 volts @ 1amp goes in. >> 30 volts out
2nd LED: 30 volts @ 1amp goes in >> 20 volts out
3rd LED: 20 volts @ 1amp goes in >> 10 volts out
4th LED: 10 volts @ 1amp goes in >> 0 volts out and the current returns to the power supply negative.


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## Anders Hoveland (Dec 13, 2014)

mnm99 said:


> I was wondering if using the this Flexblock with these led's in the series I have noted will work ok? I just don't want to burn them out on my first try.


Yes, according to the math, the power supply should work with the setup you described.
The LEDs in your circuit have a combined voltage drop load of 46.95v at 700mA. This voltage drop is greater than the minimum voltage of the power supply.

From my experience, I would caution that (unless you are substantially underdriving the LEDs) it _might_ be possible that a sudden power surge could cause a burn out. Just as a precaution, I would recommend not attaching the power supply to the LEDs until the power supply is first plugged in. There could be a power surge if the power supply is suddenly plugged in.

If there is a burnout, usually what will happen is one of the LEDs will burn out, while another one will be "damaged" (though still producing some light). The LED that burns out is the one with the lowest current rating. The LED will act as a fuse, so not all of them will burn out.

If you are extremely worried, one possible option would be adding just one more LED emitter into the circuit. This will slightly reduce the current through the circuit (since the flex block is limited to 48V).


But yes, that is what is so magical about a constant current power source, as long as the current (mA) is right, it does not matter how many LEDs you wire together in series , only so long as the total voltage of the LEDs is within the rated voltage range of the power supply.


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## Anders Hoveland (Dec 13, 2014)

I have to say that the easiest most fun way to learn about something is when you actually need to know because you are trying to build something.


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## mnm99 (Dec 14, 2014)

Thanks again..Here's one more. How much brighter will 1000ma be compared to 700ma??? I have a 700ma driver that puts out 48v. The LEDs I have to power are the *Luxeon M ROYAL BLUE 12 Watt LEDs* = Forward Voltage is 11.00V @ 700ma, 11.40V @ 1,000ma and *Luxeon ES ROYAL BLUE 3 Watt LEDs* = Forward Voltage is 2.75V @ 350ma, 2.95 @ 700ma, 3.00V @ 1,000ma. Now I can't find a driver to power 4 of the M's and 1 of the ES in series (5 total). The only way I found is with a AC/DC driver that will do 1000ma at 48v, BUT I would then have to buy a DC to AC inverter to power the AC driver. Cost of the drives would be around $50 each and the inverter I could get for around $40. Is it worth the expense of doing all that for 300ma?


Boat transom lights......Here is some progress on the light / heat sink. This is the first set with the cheap EBAY led's 3w using 2 drivers for each light, embedded in thermal epoxy. The second will be with the above Luxeon ones. The led's will be encapsulated and under water. I did it this way for water flow behind them. Should cool them pretty good.


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## SemiMan (Dec 15, 2014)

Anders Hoveland said:


> I would recommend not attaching the power supply to the LEDs until the power supply is first plugged in. There could be a power surge if the power supply is suddenly plugged in.



Ignore this bad advice. Generally much better to have the LEDs connected BEFORE you plug in the driver, not the other way around. The driver may charge up capacitors to a high open circuit voltage which is discharged into the LEDs when they are connected .... hence connect the LEDs first so this does not happen.


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## mnm99 (Dec 15, 2014)

SemiMan said:


> Ignore this bad advice. Generally much better to have the LEDs connected BEFORE you plug in the driver, not the other way around. The driver may charge up capacitors to a high open circuit voltage which is discharged into the LEDs when they are connected .... hence connect the LEDs first so this does not happen.



I understand. That kinda answers the switch question. I would connect the on off switch between the driver and battery right?


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## SemiMan (Dec 16, 2014)

Yes that is correct.


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## alpg88 (Dec 16, 2014)

mnm99 said:


> I had a little change of plans in the type of led I am using. I was wondering if using the this Flexblock with these led's in the series I have noted will work ok? I just don't want to burn them out on my first try. Thanks
> 
> *Flex block 700ma in 48V boost mode.* http://www.luxdrive.com/products/flexblock-a011/
> 
> ...



it should work, i used that driver many times. you are close to limits but not over them. also this driver has open circuit protection, it does not matter if led connected or not, prior to turinig it on.


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## mnm99 (Dec 16, 2014)

alpg88 said:


> it should work, i used that driver many times. you are close to limits but not over them. also this driver has open circuit protection, it does not matter if led connected or not, prior to turinig it on.



Thanks. So far so good. My next part is encapsulating them. I'm going to go with the MG clear. Do you think I'll have a problem?


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## alpg88 (Dec 16, 2014)

ecapsulating what???? leds?? hard to say since i do not see what, and how you'll be encapsulating, but, in general, if you leave heatsinks out, so they can be cooled by air, than you should be ok.


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## DIWdiver (Dec 16, 2014)

SemiMan said:


> Ignore this bad advice. Generally much better to have the LEDs connected BEFORE you plug in the driver, not the other way around. The driver may charge up capacitors to a high open circuit voltage which is discharged into the LEDs when they are connected .... hence connect the LEDs first so this does not happen.



+1


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## mnm99 (Dec 16, 2014)

alpg88 said:


> ecapsulating what???? leds?? hard to say since i do not see what, and how you'll be encapsulating, but, in general, if you leave heatsinks out, so they can be cooled by air, than you should be ok.



The LED's. Making for underwater. Does the picture show up? I'm looking at Clear encapsulation made by MG.

Question about the first post. Would taking out the 3w still work using the flexblock? Would the higher voltage cause a problem or does the Flexblock regulate that?

*Flex block 700ma in 48V boost mode. http://www.luxdrive.com/products/flexblock-a011/

4 - Philips Luxeon M ROYAL BLUE 12 Watt LEDs = Forward Voltage is 11.00V @ 700ma, = 44Volts*


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## alpg88 (Dec 17, 2014)

if you making them for underwater, you can get away with even smaller heatsink, but it still has to be exposed. you can not encapculate it.

yes you can add and remove any amount or type of leds, as long as voltage drop across all is not over 48v under 700ma current, you should be fine. driver does not care about types or amount of leds.


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## mnm99 (Dec 17, 2014)

Thanks. Why cant I encapsulate? 

Also I'm doing a terrible job soldering led to led. I tried 18ga solid wire and tinned it first and 16ga stranded tinned first. Put a dab of solder on the terminal and tried to solder together. Maybe my iron is too small, because it wouldn't bond if I put the iron on top. What gauge wire should I use?


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## alpg88 (Dec 17, 2014)

you can not encapsulate heatsinks. so they can be cooled by air\water.

18ga is fine for 700ma. there can be few reasons you can not solder. your iron is weak (i use 25W iron works just fine), you used no flux, you do not let the wire\contacts to get hot enough to for solder to stick. these are most common reasons, but not the only ones.


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## mnm99 (Dec 17, 2014)

I used artic silver to bond them to the aluminum. The encapsulation will be only on top of the led. I was hoping since the heatsink is bonded to the aluminum and water will be in the channel behind it that would cool enough. Doesn't the led transfer heat off the back?


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## alpg88 (Dec 17, 2014)

yes it does transfer heat off the back, where the heatsink is, you can encapsulate the top, no problems, the bottom you want to leave bare aluminum.


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## mnm99 (Dec 17, 2014)

I'm a little confused..The led with the heat sink is bonded to the bare aluminum in the dish shown. The encapsulation will go on top of the led and fill the dish to the edge. The dish is mounted to another piece of aluminum tube that I also bonded with Arctic silver adhesive to transfer the heat. The water will flow behind the led in the tube. I'm going to somehow protect the aluminum some on the outside. Either with a coat of primer and paint or something else. It will be in saltwater. The aluminum is 6063 so it's pretty resistant as it is.


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## alpg88 (Dec 17, 2014)

i can't see your pics from comp. i am on right now, i'll look at pics from home when i get there. do not want to say more untill i see pics, do not want to confuse you more.


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## mnm99 (Dec 17, 2014)

NP. Thank you


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## DIWdiver (Dec 17, 2014)

The reason you're having such a hard time soldering is that what you are soldering is bonded to an excellent heatsink. They are actually easier to solder before you glue them down, but even just the copper star makes it hard enough.

You need a good iron and a very good tip, (shorter and fatter is better), and some patience. If you can get a blob of solder on the pad to melt well, you're golden. Do that, then bring the wire in. If you can't do that, you'll never get a good joint.

For 700 mA, almost any wire size you want is fine. I wouldn't go less than 24 AWG just for ease of handling. Stranded is better if it's going to see vibration.


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## mnm99 (Dec 17, 2014)

I think I got it pretty good. I used 18 stranded. Made a blob on the pad. Tinned the wire. Then held the wire on the blob and it went down. After, I added a touch more solder on top. Seems pretty strong now.


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## alpg88 (Dec 17, 2014)

yes you seem to be good, what is mg clear? an epoxy? if yes than, :twothumbs, you can pour It in that tub, where leds sit. np.


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## mnm99 (Dec 18, 2014)

alpg88 said:


> yes you seem to be good, what is mg clear? an epoxy? if yes than, :twothumbs, you can pour It in that tub, where leds sit. np.



This stuff 
http://www.mgchemicals.com/downloads/tds/tds-8322-l.pdf


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## alpg88 (Dec 18, 2014)

DIWdiver said:


> The reason you're having such a hard time soldering is that what you are soldering is bonded to an excellent heatsink. They are actually easier to solder before you glue them down, but even just the copper star makes it hard enough.
> 
> You need a good iron and a very good tip, (shorter and fatter is better), and some patience. If you can get a blob of solder on the pad to melt well, you're golden. Do that, then bring the wire in. If you can't do that, you'll never get a good joint.
> 
> .




yes, this is most likely the case, i should have thought about it first, since i myself had experienced that before.


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