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Well I already asked some about this but now my doubts have evolved, hehe.

So, here is the thing.

If using a CV PSU in a parallel connection, V would be same and Amps would split equally between units connected right? if units are all the same.

If so, my doubts are these:

If units to be connected push 50,5V when driven at 1,15A, then, how would this PSU suit for the parallel connection:

Meanwell HLG-240H-48A

This PSU acts as CV as long as it doesn't reach current limit, once current limit is reached, it goes to CC mode. In CC mode, Voltage range is 24 - 48V. Current limit is 5A. Rated power is 240W.

In CV mode on the other hand, Current can be adjusted from 2,5A to 5A and voltage from 44,8V to 51,2V.

Units to be connected have a max current of 4120ma.

My idea is to use PSU in CV mode, adjusting Amps to 4,6A and volts to 50,5V.

So, given this config, if I connect 4 of these LED units to the PSU in parallel, those 4,6A should then be splitted en the 4 units and give 1,15A and the constant 50,5V to each? After having PSU adjusted to 4,6A and 50,5V through potentiometer??

Does this sound viable? Would current be split correctly? Do I need current limiting resistors? if so, how should I use them? What if I don't use them and just connect the 4 LED units in parallel directly to the PSU previously adjusted to 4,6A and 50,5V?

Any help will be much appreciated.

Thanks.

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1 Answer 1

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It's always a good idea to put a series resistor with the led array, remember they're semiconductors and without a resistor they are very sensitive to voltage changes. If you're not using a series resistor you should use the PSU in CC mode and define the total current that will flow through the whole circuit (in this case 4.6A) but only if the 4 units are exactly the same. Something to take care about is that if one of the units fails the current won't flow through this path, so the 4.6A programmed will be distributed among the other 3 units, in which case each one will drag about 1.5A and they can be severely damaged.

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  • \$\begingroup\$ Thanks for your answer. Thing is constant current region of PSU is at current limit which is 5A, so i guess I couldn't use it in CC mode if adjusting to 4,6A, right? Another thing is that if one of the units were to fail, if they dragged 1,5A there wouldn't be an issue with that being that each one can handle up to 4,12A max current on their own right? .... even if 2 of them fail that would mean 2,3A each which would still be in ranges.... \$\endgroup\$
    – Martin Miquel
    Commented Feb 10, 2017 at 3:34
  • \$\begingroup\$ If connecting in parallel using this PSU, how should I use resistors and which ones should i use? those would be there to limit current at 1,15A? being that 1/4 of the 4,6A? Thanks for your advice on this \$\endgroup\$
    – Martin Miquel
    Commented Feb 10, 2017 at 3:34
  • \$\begingroup\$ another thing is, why should I worry about possible voltage changes when in CV mode? wouldn't this mean voltage would reamin constant at adjusted value? 50,5V in this case? \$\endgroup\$
    – Martin Miquel
    Commented Feb 10, 2017 at 3:40
  • \$\begingroup\$ If you're using CV then you have to do this calculation. First yo need to know the total voltage dropout by the LEDs (I guess it's 50.5V as you stated before) we'll call it Vd, then the current you want to work with (1.15A for example) that we¡ll call I and then the voltage you're going to supply to the system (it must be more than Vd), we'll call it Vs. To get the required resistor you just have to calculate R=(Vs-Vd)/I \$\endgroup\$
    – Marcelo Espinoza Vargas
    Commented Feb 10, 2017 at 15:10

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