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LED driving and wiring question? Answered

I have read and read and read, and am still confused no where seems to be able to give me a straight answer, so i've come to the instructables forum for help. 

I am planing on wiring 16 leds in series driven by a driver.

The constant current driver's specs are'
in   -  85-277V, 50/60Hz, 0.5A MAx 
out -  650mA, 30-60V, 40W

The 3W leds run at 750mA, 3.2-4.0V

so each led circut should require 52.1v-65.5v,  and 48W. I was hoping to under drive them to increase their lifespan, as i had a different project fail when one led blew and killed the entire line.  

My questions are;

1) can i run 3 of these circuits off of one standard north american  plug 125V? 

2) will this work? and did i miss anything? 

3) can anyone recommend any simple improvements?

I've done as much research as i can, but i never have been good at electronics and circuits. and half of the things i find are contradictory. That's why i went into chemistry.  Thank you for reading this, and thank you for responding and helping me!



Best Answer 3 years ago

1.) Yes, easily.

2.) At the top end, at 4V led volts you just go out of spec at 650mA - I wouldn't worry about it. Your driver's maximum O/P volts is 60, your stack needs 65.

3.) Nope. Seems good to me.


Answer 3 years ago

awesome! Thank you for the reply! For queation 1) I guess my follow up question is .. how? I'm not sure I really understand how I can run 3*~60v off of a 125v plug... and how would I figure out how many I can run off of one plug?


Answer 3 years ago

That is the magic circuitry of the led driver, it holds a constant current.

If you tried running 30+ LEDs across the mains there would be serious trouble when a 5 cycle +20 voltage spike comes along, because someone shut of a big machine next door, there is no mains current limit and the LEDs may suck 2X or 3X current, They are exponential current hogs add melt / vaporize the silly die.


3 years ago

16 LEDs x 4.0 volts = 64.0 max volts

16 LEDs x 3.2 volts = 52.1 min volts

But there will be a mix of LED voltages split the differencesay 58 avg volts

The series string wants to pull 750 ma... But your driver can only deliver 650 ma....

So the driver will reduce voltage to the lamps until they pull 650 ma, which is what you want, to run them at a slightly lower power to increase their lifespan.