DiY LEDs - How to Power Them

Tazbud said:

I was looking at cree's chart for forward voltage on 3070's. I'm a bit lost understanding FV. It seems up to 42V @ 1950mA, slightly less is needed for lesser current but not proportional?

My two flower shelf drivers have voltage range -43V @ 1050mA. so... ok there.

I was heading towards another two (CXA's) for Veg shelf. The smaller current drivers in the rasnge are:

-64V @ 700mA and -86V @ 500mA..

Can I use the 500mA for two CXA's but not the 700mA?

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With your veg drivers it's either 1 @700 since the driver will not supply the minimum of 84 volts for 2 3070s or 2 @ 500 since it will supply the minimum but it's near the max voltage of the driver so I'm thinking the driver may run a bit toasty.

Just add up max voltage and that's the minimum voltage you need for your drivers. Amperage wise as long as you're under the max amperage you're golden. OK?

Ok thanks FranJan, I thought it was so, though i'm easily confused.
Think i'll set up 1x 500mA for veg, 1 driver to 2 3070, see how it runs. 2x separate1050mA flower.

I have now dived headfirst into my own DIY led project and ordered 4x Cree cxa3070 and 4x MeanWell lpc-60-1400. But after reading around a lot i have two questions that i have not been able to find the answer to, so i was hoping one of the guru's here could lend a newb a hand

First, do i need fuses for the lights? if so what amperage should they be? And do i connect one fuse per driver on the AC side?

Second is, do i need a heavy duty timer? I have seen alot of people have melted their timers with HPS, but is this also necessary with LED's? My initial plan was to get a cheap analog timer that is rated for 16A/3500W.

First, do i need fuses for the lights?
safety first, so yes

if so what amperage should they be?
depends on your Voltage...

for MeanWell LPC-60-1400
0.8A/230VAC
1.4A/115VAC

And do i connect one fuse per driver on the AC side?
yes

https://www.rollitup.org/t/looking-for-a-driver.840201/page-2#post-10764945

Thanks alot Guod!
I am running 230VAC, so i will buy a pack of the 0.8A fuses and holders.
And always safety first, that is the reason i asked

The primary job of the circuit breaker in an AC system is to protect the wire itself. So if any part of the wire between the circuit breaker and the LED driver shorts, it will pop the breaker removing the opportunity for the wire to heat up. If you want to add an extra layer of protection (for yourself) on the AC side you can use a GFCI outlet or inline GFCI. This is especially a good idea if you are working with AC power in a wet or damp environment or if you will be working around many AC connections very often. They are only $7 for 120V but may be pricey for 240V.

I sometimes add fuses to the DC side of the driver to try and protect the driver and the LED string in the case of a short or a driver malfunction on the DC side. You can size the fuses based on the output current of the driver and you can get fast-blow round fuses and fuse holders reasonably cheap at most hardware stores.

The Mean Well LPC-60 series has built in protection for short circuit and over voltage on the DC side

SupraSPL said:

The Mean Well LPC-60 series has built in protection for short circuit and over voltage on the DC side

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The drivers I bought had over-current, over-temp, and over-voltage protection
They weren't as economical though.

Hello! I'm building a few lamps around Meanwell HLG-120H-C700A. They are dimmable from 350-700 mA.

I accidentally bought 24 gauge cable, which is rated for 577 mA. Do you guys think it will be ok to run 700 mA? The cable will only be about 6 foot long in total.. This should be ok, right? I don't care if there is a minimal loss in efficiency, but if there is substantial loss or unsafe, i really need to undo some soldering and invest in 22 ga cable.

It would help a lot if anyone had an answer! Great thread buy the way! It was great input here that made me go with these drivers.

Ok. I think i found the answer to this on this page. http://www.powerstream.com/Wire_Size.htm

It seems like 24 ga will give me a voltage drop of 2,16 percent if the wire is 7 feet. Still it's the wire stevesleds recomends for 3 watt leds... Hmm. Maybe most folks doesn't use 110V-drivers..

Fiveleafsleft said:

Hello! I'm building a few lamps around Meanwell HLG-120H-C700A. They are dimmable from 350-700 mA.

I accidentally bought 24 gauge cable, which is rated for 577 mA. Do you guys think it will be ok to run 700 mA? The cable will only be about 6 foot long in total.. This should be ok, right? I don't care if there is a minimal loss in efficiency, but if there is substantial loss or unsafe, i really need to undo some soldering and invest in 22 ga cable.

It would help a lot if anyone had an answer! Great thread buy the way! It was great input here that made me go with these drivers.

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no if anything you should be using a cable with a higher rating than 700mA, if that will be your final current. Squeezing more current into a cable not designed to handle it, is going to end badly.

safety meeting said:

no if anything you should be using a cable with a higher rating than 700mA, if that will be your final current. Squeezing more current into a cable not designed to handle it, is going to end badly.

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Thanks fpr yout reply! I'm not sure if i will go higher than 577 mA, since my grow space is small and i like the efficiency advantage of lower amps. But creating unnecessary restrictions seems stupid.. Playing with the calculator i linked to in my previous post, tells me that you are right when you advice me to oversize the cables. There is a significant loss even from 22 ga..

But are you sure it really is dangerous to go with 24g? I imagine the copper would get a degree warmer and thats about it.. but then again, i'm just speculating. (i'm also one of those guys that keeps asking till i get the answer i like...) Also find it strange that stevesled recommends 24 ga for 3 watt leds...

The reason i'm so stubborn is that it seams impossible to find solid copper cable where i live, and that i find it very difficult to solder with the twinned cable. I'm also able to only use the 24 ga cable on my 8 small heat sinks and use heavier duty cable to connect them in series with my two drivers. This would leave me with less than 2 foot 24 ga cable per driver and a loss of 0,5 % volts, which i find acceptable..

Hey guys..

I have a simple question that doesn't really require a thread so was hoping the lighting gurus could help me out a bit in this one

I'm am looking at getting 18 of these Philips from rapid http://www.rapidled.com/solderless-philips-rebel-es-660nm-deep-red-led/ as my entry in to DIY...

I'm was after some advice on what meanwell driver or drivers I would need to power these...I will be using them on two heat sinks running as side lighting 9 on each heat sink

if 18 can be run on one driver that is fine and if i need two then also I don't mind..

Also is it possible to work out via rough calculation what the total draw would be.. I don't have a multi meter and like I said, its an entry level DIY project to see how I go...

Hi Dox, what you want is pretty straightforward. Finding the info you need is harder.

http://www.philipslumileds.com/products/luxeon-rebel/luxeon-rebel-color#deep-red

So if it's an LXM3 the most voltage each will use is 2.8 volts. So the driver you need to run 18 of them would be a constant current driver that supplies no more than 700mA, which is the max amperage you can use on a LXM3 660, and at least 50.4 volts (18 LEDs x 2.8 volts) or say 51 volts. So the driver you want must supply 51 volts or above at least, so 49 volts would be no good but 52 volts would be fine. The current you want to use is up to you just don't go over 700mA and you'll be okay. Now if you run at a lower amperage, the voltage used by the LEDs will go down (1.8 volts per LED), but the above way of selecting a driver will make sure you'll have enough voltage in all situations. Oh and wattage is whatever the amperage is x the total voltage. Actual wattage will be a bit higher because of driver overhead and any other inefficiencies.

I think 2 drivers would be better for you btw. Just in case of driver failure you won't be up a creek without a paddle.

Good Luck!

FranJan said:

Hi Dox, what you want is pretty straightforward. Finding the info you need is harder.

http://www.philipslumileds.com/products/luxeon-rebel/luxeon-rebel-color#deep-red

So if it's an LXM3 the most voltage each will use is 2.8 volts. So the driver you need to run 18 of them would be a constant current driver that supplies no more than 700mA, which is the max amperage you can use on a LXM3 660, and at least 50.4 volts (18 LEDs x 2.8 volts) or say 51 volts. So the driver you want must supply 51 volts or above at least, so 49 volts would be no good but 52 volts would be fine. The current you want to use is up to you just don't go over 700mA and you'll be okay. Now if you run at a lower amperage, the voltage used by the LEDs will go down (1.8 volts per LED), but the above way of selecting a driver will make sure you'll have enough voltage in all situations. Oh and wattage is whatever the amperage is x the total voltage. Actual wattage will be a bit higher because of driver overhead and any other inefficiencies.

I think 2 drivers would be better for you btw. Just in case of driver failure you won't be up a creek without a paddle.

Good Luck!

Click to expand...

My like button is gone but thanks for the advice...I appreciate it

its early days in this project so will take it all on board and h ave a look online for a few drivers... will probably report back here before the final purchase though...

EDIT...

in regards to the total wattage...(in a rough estimate).. I assume the 700mA is 0.7 when you multiply it by the voltage?

and


Is it possible to go over the volts required IE 60 or 70 volts as long as the amperage is within range?

You're welcome.

Yes it's OK to have a driver that gives 60 or 70 volts in this case. The LEDs will only "take" what they need, and if anything the driver would not have to work at it's maximum capacity. As always just stay under the max amperage.

FranJan said:

You're welcome.

Yes it's OK to have a driver that gives 60 or 70 volts in this case. The LEDs will only "take" what they need, and if anything the driver would not have to work at it's maximum capacity. As always just stay under the max amperage.

Click to expand...

One last naive question... I see drivers have a rated power.... for example... 0.76mA 54V rated power 40W driver...is this how much power the unit will use or does this mean how much it will power the string of LEDS up to?


Regards and thanks again for taking the time to help

It's roughly the maximum amount of watts the driver will draw under full load. It's actually redundant in a constant current setup at least since you know .76 Amps x 54 volts= 41 watts or 40 watts but it does remind you that your circuit, with overhead, should not be drawing more than 40 watts. You do want to stay away from using the driver at it's maximum rating since this puts a heavier workload on the driver and will produce more heat So if you have a 2 Amp COB LED you want to run at around 40 watts, which is 1 Amp x 40 volts = 40 watts, you would get a constant current driver that produces 1 Amp and at least 40 volts but since there is always some power lost somewhere to overhead you'd be better off getting a driver that does 1 Amp and 50+ volts, (50+ watts), and now you have a bit more overhead here. The circuit takes what it needs to run. It will not run at 50 watts because you're using a 50 watt driver, it will only draw 40 watts and the "50 watt" driver can supply that easily. See what I mean?

Don't worry about watts in an LED circuit per se. Voltage and amperage are your keys, watts are just the product of the circuit.

Am I helping or hurting you here? LOL

FranJan said:

It's roughly the maximum amount of watts the driver will draw under full load. It's actually redundant in a constant current setup at least since you know .76 Amps x 54 volts= 41 watts or 40 watts but it does remind you that your circuit, with overhead, should not be drawing more than 40 watts. You do want to stay away from using the driver at it's maximum rating since this puts a heavier workload on the driver and will produce more heat So if you have a 2 Amp COB LED you want to run at around 40 watts, which is 1 Amp x 40 volts = 40 watts, you would get a constant current driver that produces 1 Amp and at least 40 volts but since there is always some power lost somewhere to overhead you'd be better off getting a driver that does 1 Amp and 50+ volts, (50+ watts), and now you have a bit more overhead here. The circuit takes what it needs to run. It will not run at 50 watts because you're using a 50 watt driver, it will only draw 40 watts and the "50 watt" driver can supply that easily. See what I mean?

Don't worry about watts in an LED circuit per se. Voltage and amperage are your keys, watts are just the product of the circuit.

Am I helping or hurting you here? LOL

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Seriously man... its a great starting point... just the shit I needed to understand... it isn't so much the building but the calculations of it all... I have lurked for a while on here so I know you guys more than you know me and this place seems to be full of lighting sluts and who doesn't love a slut...I mean that in the highest possible regard BTW!!!

I spent my morning looking at various drivers getting my head around their data sheets so you may have created a monster...

Ok just wanna share the answer I got from Steve led when asking about 24 ga cable and higher Amps.

"I calculate that 24 GA solid core can handle up to 3.5A.

Can your provide your reference equation?

Thanks!
Jeff"

My reply:

Reading a bit further in to The subject tells me that 0,577 is the generic textbook recommendation for transfer of electricity with 24 ga. The calculator I used didn't take chassi-wiring in to account.. A real calculation of max amp has to deal with factors as: length of wire, bundle of wires or not, surrounding temp, tolerated drop of Volts, and type of insulation etc.

I will use about 1,5 feet of wire, and my new data tells me that it won't be dangerous at all. Temp in cable will raise about 10 degrees, and I will have a volt-drop of about 0,7%. I find this acceptable but would probably have opted for a slightly thicker cable if I knew what I now know..

3,5A is the same max current for chassi wiring as I have found, but that would give a raised temp of about 30 degrees in cable, and a significant drop in voltage if my sources are accurate..
Thanks for your reply, I know feel that it's at least safe to go with 24 ga. And as I said it really is nice to solder with it!

I Might as well share he latest reply i got from Jeff at stevesled, even if I do find it a bit to good to be true...

"We have been using the 24ga for the past 5 years and almost 9,000 customers running at 1A, with a temp rise of less than 0.50 degrees F, when measured with our FLIR camera.

You won't have an issue with it."