I have an LED power supply – constant current with output 1.4A/96W/23-69VDC. I want to buy a number of LEDs and connect these in series.
What do I need to calculate to know how many of the following LEDs I can add to this power supply?
Can I just do it all by Ohm's law?
https://www.led-tech.de/en/CREE-XM-L2-T4-on-Star-PCB
My calculation results in approximately 48 LEDss (though I would only want to push the power supply to say 80% which gives more like 38.)
Just wanted to see if I made this right here since it was a while I did this.
Best Answer
According to the datasheet, the LED's Vf is 3.05V @ 1500mA, which is close enough to the 1400mA constant current provided by your power supply.
The power supply's maximum output voltage is 69V.
69V / 3.05V per LED = approximately 22 LEDs in series. Say 20 to have some margin.