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# Using a 1500mA LED driver to power 1400mA of LEDs? Answered

I am building a light panel to grow lettuce indoors and need some help. I am relatively new to electronics and trying to learn.

The LEDs are:
Max. Forward Voltage: 3.0-3.6V
Max. Forward Current: 700mA

The LED driver:
DC20-39V 1500mA +-5%

I have done the calculations and will be using 20 LEDs in 2 strings with 10 LEDs in each resulting in 1400 mA at 36.0 VDC. So I bought the LED drivers stated above with the current knowledge i had. But after learning about Constant Current LED Driver, I'm not so sure anymore as the LEDs will not draw what they need, instead be supplied with a constant 1500mA.

Am I correct to assume that the LEDs will be fried driven in this configuration?

Is there a way to make it work or is the only option to buy a 1400ma LED driver?

Many thanks!

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## Discussions

Thanks for your input and valuble information. I will redesign and use one or multiple 700mA LED drivers to drive the LEDs in series as per your suggestions.

What you need is a 700mA constant current driver, that can put out 80V or so. You CANNOT run these high power diodes in parallel chains.

I recommend a proper driver, otherwise you will waste a lot of energy.

Electronic item draw current as they need it so as long as the power supply can provide the maximum current that will be demanded then all is OK. LEDs may be a different issue (see below)

The Power supply will NOT drive excess current through anything if it is not required.

LEDs in series will increase the voltage required but not the current LEDS in parallel will increase the current required but not the voltage.

AN LED is almost a short circuit to the power source, to prevent it drawing too much current there has to be something in the circuit to limit the current - This is usually a suitable resistor (many calculators for the resistor(s) on line) or a current limited power supply.

Caution - if you put several high power LEDs in Parallel and one fails then the extra current it was using will be shared through the others often leading to further failure if no other action is taken to limit the current.

http://led.linear1.org/led.wiz

http://led.linear1.org/category/led-basics/