3.7v or 4.2v for calculating resistors?

Hey all,
Going to start a Tri-Cree RGB hilt using one of my many 3.7v 18650's as the power source. I know how to calculate resistor values needed, but not sure if I should calculate input voltage as 3.7 or 4.2 (fully charged pack). Or, should I calculate both and average them out?
Thanks!

Use the 3.7V value.

Thank you FJK! I'll calculate the 3.7v value.

I would also check out Erv's video on how to calculate actual vF for individual LEDs, as the datasheets can sometimes be inaccurate. It requires a benchtop PSU.

https://www.youtube.com/watch?v=S5IICsTwTYE

Quote:

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Originally Posted by BlessedWrath

I would also check out Erv's video on how to calculate actual vF for individual LEDs, as the datasheets can sometimes be inaccurate. It requires a benchtop PSU.

https://www.youtube.com/watch?v=S5IICsTwTYE

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A tenth of a volt here or there won’t really matter. The resistors are usually rounded up anyway, which covers inaccuracies in voltages.

Rounded up on the TCSS calculator and ordered the proper ones. Thanks for the help & input!