Resistor check

[Fuzzy_Jedi_Slippers]

First off thank you in advance, if you have clicked on this post you are a kind person who is willing to answer the often asked question about resistors and olm's law.

Early one morning I did my calculations without a drop of coffee in me, I came up with needing two 1 om 2w resistors for my LEDs. I ordered, received and wired them confidently. After visually inspecting the wiring against the diagram from the NBv3 manual, I did a test using my wired up battery on exposed wires, careful to only expose the LEDS to a brief couple of seconds. It was a success!

So on to my question. After wiring everything for some reason I decided to revisit Olm's Law to triple check everything and this time my calculations came out different. Before wiring my LEDS to my sound board I want to make sure I have not goofed up.

Green/Green/white Cree XP-E2

Green R=1.2= 4 (battery rounded up) - 3.58 (forward voltage) / .35 (max current in amps)

White R= .85= 4 - 3.15 / 1

So in short both need a 1om resistor....

It's the wattage I'm way off on.

Green P= .147= 1.2 × .1225
White P= .85= .85 × 1

Ok? So my Green resistor should be a 1.2 om .147w which of course does not exist.
And my white should be a .85 om .85w ? Did I do something weird in my math. Long term what will happen if I run my LEDs with 1 om 2w resistors instead?

[Silver Serpent]

There's no need to round up your battery value. 3.7 is a perfectly safe value.

Your current value should typically be 1000mA or 1 amp. The 350mA value is just to turn the LEDs on. They run much better at higher values. 1A is safe, and is the typical value we use (it also makes the math easier!)

When you calculate the wattage, the value you get is a minimum. You can always use a higher wattage resistor, and it won't affect the brightness or the safety of your components. Don't go overboard, since 5w and 10w resistors are HUGE and take up a lot of valuable space in your hilt.

Long story short, your 1 ohm 2 watt resistors are fine.

[rlobrecht]

Your larger resistor is fine. Ohms you want close (and greater) to the calculated value. Larger Watts means a physically larger resistor, but otherwise doesn't impact your circuit.

[Fuzzy_Jedi_Slippers]

Thank you for your quick replies!