3V battery for 1.8-2.2V LED

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lukutu
 
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Joined: Sat May 21, 2022 7:41 am

3V battery for 1.8-2.2V LED

Post by lukutu »

Hi, I see a lot of videos that show an example of a ~3v LED burning out using a 9V battery and that you need a resistor to prevent that from happening.

I have a red/green LED that is marked as 20ma with 1.8-2.2V. I have two battery cells, each 1.5V, to make up a total of 3V. When I connect it, the LED does not burn, probably because it isn't providing too much current all at once. However is it safe to keep it like this? If I leave it for a long time, would it burn out? I don't see how feasible it is to have a resistor of size 1V to prevent this. How do circuit boards or other LED professionals wire it up such that red 1.8-2.2V don't burn out?

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adafruit_support_bill
 
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Re: 3V battery for 1.8-2.2V LED

Post by adafruit_support_bill »

You can use a resistor calculator like this to determine the appropriate resistor
https://www.digikey.com/en/resources/co ... s-resistor

With a 3v battery and a typical red LED with a forward voltage of 1.8v and rated for 20mA, you would need a 60 ohm resistor.

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