There is some unknown factor here. I need to use an LED to light an area of a device. The device has a 12V, 6A power supply. I was expecting to have to reduce the current from 6A in order to use the 12V LED but the LED is working as -is, connected directly to the 12V, 6A supply. How can this be? I expected the LED to get hot or to burn out. It isn't even getting warm. I'd like to know why.
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3 Answers
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Power supplies don't push current; loads pull. 6A is the maximum current that the supply can provide, but it's perfectly happy to supply less. If you have a load that's rated for 12 volts and you attach it to that supply (or any other 12 volt source) it will draw the current that it needs.
answered May 17, 2019 at 12:54
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\$\begingroup\$ It's this kind of answer with explanation that newbies like myself really appreciate, to drive home the basics before bad thoughts happen to us =) \$\endgroup\$ May 17, 2019 at 20:13
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The LED already contains the appropriate resistor to reduce the current to an acceptable level given a 12V power supply.
answered Jul 31, 2015 at 21:01
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\$\begingroup\$ Logical, there are no details on the LEDs. Should they not get warm due to the resistor? \$\endgroup\$– KayBeeJul 31, 2015 at 22:23
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\$\begingroup\$ 12V times 20mA is 240mW. That is true regardless of the resistor. \$\endgroup\$ Jul 31, 2015 at 22:25
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You had to connect a 12V LED directly to 12V! There is a build in resistor, so the current will be fine.