This will be my first time trying to power my Arduino from an external source rather than an USB port.
I will need to power my Arduino Nano (Rev 3.0) with an external 24V DC power supply (from a 24V, 36Ah lead acid battery), so I was wondering what I could do.
I have three possible solutions:
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Connect the 24V power supply to a 24V-to-12V DC buck converter, and supply the 12V voltage to the Vin pin on Arduino Nano to power my Arduino Nano.
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Connect the 24V power supply to a 24V-to-12V DC buck converter, and supply the 12V voltage to a voltage regulator (LM7805), and supply the 5V voltage to the 5V pin on Arduino Nano to power my Arduino Nano.
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Connect the 24V power supply to a voltage regulator (LM7805) directly, and supply the 5V output voltage to the 5V pin on Arduino Nano to power my Arduino Nano.
Do all of the 3 solutions work theoretically? Will all of them successfully power the Arduino Nano? Which one is better?
EDIT
I will get my 24V DC supply from a 24V, 36Ah lead acid battery, and I will use my Arduino Nano to power a DC motor via L293D and buttons. I am not sure how much output current I will need, but I think it wouldn't be a lot. Will the 24V, 36Ah lead acid battery affect my choice?
Best Answer
The most efficient solution would be to use a 24V->5V DC->DC converter.
Adding a 7805 at any point will simply waste power - the 7805 (or any other linear regulator) just acts as a resistor. The current drawn from the 24 volt source will equal the current required by the Arduino (plus a bit for the regulator operation).
With a DC-DC converter, the power drawn (not the current) from the 24V source will equal the power required by the Arduino (plus a bit for the DC-DC converter operation and inefficency).