How do i figure out what led driver i need

[John08007]

I am in the process of rebuilding a chinese blackbox light. It had some burnt out led's and a bad driver. I purchased replacement led's, they say 3.2-3.4v, 700ma, 3w. I understand with them in series i add up the watts to get the total wattage. But what i cant fig out is the voltage. Everything i read says 12 or 24v, dont i need to get a driver that puts out 3.2 volts?

 

[Lasse]

You need a driver that put out a constant current at max 700 mA and variable voltage with maximal output at least to 3.4 V x how many LEDs you have connected in the serial chain (daisy chain) Look for constant current drivers

Sincerely Lasse

 

[John08007]

Thats what i was thinking after i posted this. So for example 10x 3.4-4.0v led's in serial then i need a 34-40 volt driver, correct? How does the variable voltage work, they have a potentiometer to adjust the voltage?

 

[Lasse]

Nope it adjust itself. Please Google constant current led driver

Sincerely Lasse
.

 

[Michael Lane]

I am in the process of rebuilding a chinese blackbox light. It had some burnt out led's and a bad driver. I purchased replacement led's, they say 3.2-3.4v, 700ma, 3w. I understand with them in series i add up the watts to get the total wattage. But what i cant fig out is the voltage. Everything i read says 12 or 24v, dont i need to get a driver that puts out 3.2 volts?

The black box lights typically have the LEDs in one channel in series, so you'd need to add up the forward voltage of each LED in the string and use a driver that supports that voltage. I think the black box drivers are around 90 volts output. I haven't had much luck sourcing drivers that can work at that voltage with a current above 300mA.

 

[bblumberg]

Meanwell makes a dizzying spectrum of drivers. You can easily get several hundred volts at 700+ mA. The question is whether you want to have this much electricity near water.

See here for the full list
http://www.meanwellusa.com/product/led/LED.html

I like the HEP series to power LDD-H drivers and the HLG series to do what you are considering. f you want between 95-190v and 525-1050 mA, then maybe this one HLG-185H-C1050. Or pick another one that fits your needs.

Are you quite sure that all of the diodes are in series in a single channel? They might have some channels in parallel to keep the voltage needs down.

 

[John08007]

I was thinking once i desolder the diodes i could get out a continuity meter to make a road map, confirming that they are in series

 

[oreo54]

3.2-3.4v, 700ma, 3w. I understand with them in series i add up the watts to get the total wattage. But what i cant fig out is the voltage. Everything i read says 12 or 24v, dont i need to get a driver that puts out 3.2 volts?

You got the help on the voltage thing..but keep in mind that the diodes you bought AND the ones still good can vary quite a bit..
But getting to the Wattage thing.............above is incorrect.
3.4 x 700mA =2.38W each..3W is more of a "class" thing sort of telling you max wattage..

most BB drivers are 550mA so 3.4(actually slightly less at that mA ) x .550 =1.87 W
55 x 1.87W = 102w not 165W

Meanwell does make some large DC voltage drivers but most fall in the "out of range" for one reason or another.
The bigger ones do have an "AB" series which is dimmable (b) and you can adj the current (a) but most apper to be special order..
normally you can just get dimming OR current adj.
There may be others since Meanwell makes a heck of a lot of "stuff"..

Inventronics made some more equivalent to bb drivers but hard to find..

On continuity/diode/low Ohms a digital VOM "usually" will dimly light A(1) diode w/ the correct polarity..
Testing many in series is a bit different.
You can use like 9v battery to test 2-3 in series..
you can build a test "driver".. i.e meanwell LDD-HW (LW) w/ low mA and a power supply.
Voltage max of ps will determine how many in series one can test...How few is one (V(f) needs to be greater than driver minimum which I believe is 2V-ish ..
i.e 24/3.4 = 7
Also keep in mind 7 at 350mA will test "bright"..so don't stare at them..

HLG-120H-c1050(AB)
"Best fit" if you can find it..
74-128V
525-1050mA current

https://www.meanwell.com/Upload/PDF/HLG-120H-C/HLG-120H-C-SPEC.PDF

 

[bblumberg]

HLG-120H-c1050(AB)
"Best fit" if you can find it..
74-128V
525-1050mA current

https://www.meanwell.com/Upload/PDF/HLG-120H-C/HLG-120H-C-SPEC.PDF

Both A and B variants are in stock at Mouser...

 

[oreo54]

Both A and B variants are in stock at Mouser...

Yea but no "AB"...................

 

[John08007]

Ok, i used a meter to determine this led fixture has 3 channels of led's, channel 1 and 2 have 26 in series, channel 3 has 3 in series. The led's that i purchased off ebay are all 700ma, 3.2v-3.4v except 425-430nm are 3.5-4v, the original drivers for the 2 main channels are 55-85v, 570-590ma. I am assuming that since the ma is different i need to replace the drivers?

1 other thing, am i correct that since the original led's must have a lower ma that i camt mix and match orig with new led's?

 

[oreo54]

Ok, i used a meter to determine this led fixture has 3 channels of led's, channel 1 and 2 have 26 in series, channel 3 has 3 in series. The led's that i purchased off ebay are all 700ma, 3.2v-3.4v except 425-430nm are 3.5-4v, the original drivers for the 2 main channels are 55-85v, 570-590ma. I am assuming that since the ma is different i need to replace the drivers?

1 other thing, am i correct that since the original led's must have a lower ma that i can't mix and match orig with new led's?

The mA is a sliding scale..
The drivers "set" the mA output by changing the voltage..

As long as the string doesn't go under 55V total or over 85V total (@ 580-ish mA) there is nothing to change..

mAybe think of it this way..the current draw and voltage are all a co-related sliding scale. It's not in any way a "set" number..

As you increase the voltage across the diode it "draws" more current.
When a driver "locks" the current at 550mA say it will increase the string voltage till it reaches that point.
After that it will run in relatively steady state.. supplying enough voltage to keep the current stable and at it's setpoint.

700mA @ 3.2-3.4 is only ONE point in a continuum..

https://www.ledsupply.com/blog/constant-current-led-drivers-vs-constant-voltage-led-drivers/