3.7v or 4.2v for calculating resistors?

[ViperR]

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!

[Forgetful Jedi Knight]

Use the 3.7V value.

[ViperR]

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

[Weaver]

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

[Forgetful Jedi Knight]

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

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

[ViperR]

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