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I am using a Nokia mobile charger that can output DC 5V at 350mA. I am connecting a 63 LED panel (salvaged from an old emergency light) to the charger directly, and the LEDs glow. I removed all the circuits from this emergency light, and only kept the LEDs panel, connected directly to the charger.

From what I know, an LED needs about 20mA of current, so 63 LEDs in my setup will need 1260mA of current. The charger I am using only outputs 350mA. How are the LEDs still glowing fine? What is happening here?

Basically I want to know what will happen in these cases:

1) If the item draws more CURRENT than what the power source can provide, what will happen?

2) If the source can provide more CURRENT (say if I switch to a 2A charger) than what the LEDs can consume, what will happen?

PS: I just play with these things, so my knowledge in this area is very limited.

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closed as too broad by Eugene Sh., Trevor_G, Leon Heller, laptop2d, Dave Tweed Oct 3 '17 at 12:03

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Basics are best explained in the subject textbook. SE is not a tutoring site, but for answering specific questions about electrical and electronic design. Some specific theoretical questions are acceptable too if some research effort is shown. \$\endgroup\$ – Eugene Sh. Oct 2 '17 at 17:54
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A LED is starting to glow at a much lower current than 20mA and they will even produce current if you put light on them.

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The 20 mA spec you often see for LED current is the maximum recommended current - LEDs will work at much lower currents (but will produce less light).

Your charger is rated to produce up to 350 mA. If you attempt to draw more than that, the output voltage will probably drop, and the charger will overheat, and may be damaged.

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