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I'm doing a project that involves an Arduino Nano, a sound detection microphone module and a RGB Led strip (individually adressable leds). I also bought an accumulator so I can connect everything straight to the outlet.

The problem is that on 12V this accumulator cannot power the led strip at all and when I connected it to the laptop the Nano micro USB fried after I did about 4 tests.

My question is why can't the accumulator power everything and why the Nano got fried from the laptop which should have even less power? Would an Arduino Mega solve the problem or is it something about the wiring? (the wiring was checked by someone with experience)

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    How big is your strip (how many LEDs)? And are you providing it with power through the Arduino? – chrisl Jan 10 '20 at 18:24
  • what is an accumulator? – jsotola Jan 10 '20 at 19:17
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I assume you are powering the Nano through VIN or USB, and you are then powering the LED strip from the Nano's 5V pin.

  • From the 12V battery the current flows through an LM1117 linear voltage regulator. Draw too much current (>800mA) and it will overheat and either shut down (if it's a good one) or melt (if it's an inferior Chinese clone).
  • From USB the current flows through an SS1P3L diode with a maximum rating of 1.5A. If you draw more than that you will blow the diode and the board will appear dead.

So basically you're drawing too much current.

The proper way of powering a setup like this is:

  • USB connection to power the Arduino only
  • 12V into a 5V switching ("buck") regulator rated for at least the maximum current the LED strip needs
  • 5V switching regulator into the LED strip directly
  • Connect the ground of the 5V to the ground of the Arduino

or

  • 12V into a 5V switching ("buck") regulator rated for at least the maximum current the LED strip needs
  • 5V switching regulator into the LED strip directly
  • 5V switching regulator also to the 5V (and ground) pin of the Arduino to power the Arduino

or

As above but with a 5V power supply instead of the 12V and switching regulator

Note that it is important that your supply can provide you with at least as much current as the peak current your system will need. If that is a problem then you can split the LED strip into chunks and power each chunk separately from a lower current supply.

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