It is not just the extra heat in the LED that may be shortening there life.
I have 7 LEDs on each blade, They are rated at 20mA each. That should be a total draw of 140mA on the pack. When I used the resistor that the calculator said for 3.7V the 7 LEDs were pulling 525mA measured. Once I put in the LEDs for 4.2V I was getting the correct 140mA for the full duration of the battery. I could not tell the difference in brightness with just my eyes, I still had to crank up the lighting on the heli so the blades did not wash it out.
The battery I use is a 200mAh LiPo. it is only rated for 2 C discharge. With the lower resistor values I was exceeding the max output rating of the LiPo. Some people are using even smaller cells. Measure you current to be sure you are not risking the LiPo.
I never checked to see if different online calculators gave different results. They shouldn't, but we'll never know till someone gets ambitious enough to check.
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Jeff Borowski
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