how to work out MA of driver ?

hey guys so i have been looking at LEDS which are 350ma

now what i want to know if i see a driver which is 30watt, and it does not say what ma it is but does say the Amp and such how can i work out if say 3 leds each running 350ma will work in series ?

also if i put 3 leds in a series will it add up each 350 so in total thats 1050 or is it just 350ma ?

last question would a driver which is 30 watt and 3.3amp cook an led which runs just 350ma ?

littlegrow said:

hey guys so i have been looking at LEDS which are 350ma

now what i want to know if i see a driver which is 30watt, and it does not say what ma it is but does say the Amp and such how can i work out if say 3 leds each running 350ma will work in series ?

also if i put 3 leds in a series will it add up each 350 so in total thats 1050 or is it just 350ma ?

last question would a driver which is 30 watt and 3.3amp cook an led which runs just 350ma ?

Click to expand...

You are wright and wrong at the same time dude !

The '30W' statement means the driver is designed for a maximul power of 30W.
On it's label you will find the constant current output, in mA or A (does not matter, is just a question of math 1A=1000mA).

You really skipped the physics class, don't you ? When two ore more devices are connected in series, the current passing that chain of devices is the same wherever you measure it.

And yes, a 3.3A driver will instantly cook any 350mA led which have a voltage drop lower than the driver output.

Don't choose the leds starting with the driver. Pick the LEDs you want to use and find a matching driver.

lol

you could take a 1750mA constant current adapter and make a parallel circuit connecting 5 LEDs that are powered at 350mA each. A circuit in a series is connecting the positive of the driver to the positive on an led, then the negative of that LED to the positive on another LED until you get to the end and run the negative from the driver into the negative of that last LED, that would power each LED at 1750mA and burn them out if they are rated for 350mA A parallel circuit would be wiring the positive AND negative from the driver to an LED, then connect the positive AND negative from that LED to the next LED.

in a serial circuit, the forward voltage required to power all the LEDs needs to be added up, so if an LED takes 3.3V, and there's 3 of them, that's 12.9V forward voltage required to power that. If the driver is 1750mA, Each led would receive 1750mA, which would burn out a lot of LEDs. Also, many LED drivers have a minimum Voltage as well, so if you have an LED that happens to run at 1750mA, but only takes 5V, but the drivers minimum voltage is 10V, it will fry that LED that way too.

If you do plan on splitting up the output of a driver like this, each segment should have very similar if not exact same forward voltage.

frying an LED happens in a split second, so be careful.

in a parallel circuit, the forward voltage the driver needs to output is only added up in one section of the parallel circuit, so if you have a 1750mA driver and 15 3.3V LEDs, and you wire 5 sets of 3 LEDs in a series and wire the positive and negative of the driver in a parallel circuit to the 5 sets of 3 LEDs, The driver will still only need to power 12.9V forward voltage, but each set of LEDs will draw only 350mA, the 1750mA current divided by 5.

If you go this route, really check that your soldering is solid, because if the parallel circuit broke after the first LED set for example, that 1750mA would all wind up in the one set of LEDs and likely damage them.