Powering an Arduino Nano with a 12v Battery

Hello everyone and thank you for taking the time to read my question :slight_smile:

I have been working on a project and do not know how to continue. There is probably a simple answer but I cannot seem to find it anywhere or I just suck at researching :slight_smile: I have been wondering whether I can power my Arduino nano on the vin and gnd pins with a 12v 4.5Ah batterie I feel as though that current would kill the Arduino or am I wrong? do I need to buy some extra bits so I can run the Arduino on the batterie or can I hook it up directly? Thank you :slight_smile:

Yes, you can run the Nano from 12volt.
No, you can't draw any current from the Nano (for sensors/LEDs) at that voltage.
Better to use a DC/DC (buck) converter to drop that voltage to e.g. 5volt. Pololu has a good range.
A car phone charger with USB socket could also be a good solution.
Leo..

I feel as though that current would kill the Arduino

Your feelings would be wrong. The nano itself will only use as much of the available current as it needs. As long as the batteries can source that much, all is good. If the batteries can source more, no big deal. The problem comes if you wish to power anything else off the 5V pin of the nano, like Leo says. The onboard regulator has to dissipate all the voltage over 5V as heat. The more current you try to use, the more heat is produced, and it wouldn't take much to destroy the regulator.

Phil-Henrich:
power my Arduino nano on the vin and gnd pins with a 12v 4.5Ah batterie I feel as though that current would kill the Arduino or am I wrong?

All what current? Ah isn't a measure of current.

Wawa:
Better to use a DC/DC (buck) converter to drop that voltage to e.g. 5volt.

Does a buck converter have high efficiency or can I just use a 5v voltage regulator(Which has probably got worst efficiency) would the regulator also do the job? Thank you for answering (:

Think of it this way - when you open the tap and water comes out, that only depends on
the pressure of the water, not the size of the reservoir containing it.

Phil-Henrich:
Does a buck converter have high efficiency or can I just use a 5v voltage regulator(Which has probably got worst efficiency) would the regulator also do the job? Thank you for answering (:

Buck converters are efficient. Just watch this video if you want to know.

Don’t bother with the linear voltage regulators because your Arduino Nano already has one connected to the VIN pin.

You have to elaborate your project and the components or modules you are using, only then can you determine the power supply. For example if you use a lot of modules that run on 5V then you shouldn’t connect them to your arduino 5V pin or if you have a lot of 12V modules then you can simply connect them directly to VIN and GND instead of buying a buck converter.

tinman13kup:
The problem comes if you wish to power anything else off the 5V pin of the nano

This might be a stupid question but does this include connecting a potentiometer to 5V pin?

Or maybe better to ask, will this work without a buck converter or do I need one in order to power arduino with less volts?

Thanks

  1. Yes the potentiometer counts as something driven by the 5V pin, though the impact is negligible. Ohms law applies... 5V, 10,000 Ohms = 0.5mA. Will that impact the onboard linear regulator... no... not really... but it is part of your total current budget.

  2. When the onboard regulator (which does not have a heatsink) is fed 12V, that voltage drop required to reach 5V needs to be dissipated by the regulator as heat. Regulators have current ratings, like 1.5Amps, for example... but that is based on a temperature of 25C inside the part. If the heat is not dissipated, you must DE-RATE the regulator... meaning... reduce the total load current to help keep the part within nominal operating temperature. If it gets too warm... it just shuts off to protect itself. Feeding 12V into Vin often means that you only have a budget of about 500mA and that must include the 75mA to 100mA the board is already using.

1 Like

pwillard:
Feeding 12V into Vin often means that you only have a budget of about 500mA and that must include the 75mA to 100mA the board is already using.

Even a Mega, with a larger regulator and more heatsink area, will eventually shut down if you draw more than 150mA from the 5volt pin with 12volt on V-in.

A Nano has virtually no heatsink for the 5volt regulator.
Educated guess is that the regulator eventually will shut down with a dissipation of >=0.5watt in the regulator.
12volt on V-in (RAW) means 12-5= 7volt across the regulator.
That's a total current budget of 0.5watt/7volt = ~0.07A = 70mA.
The Nano itself draws about 30mA, so a Nano could shut down after a while if you draw a combined current of more than 40mA from the I/O pins, the 5volt pin, and the 3.3volt pin.

@ pstruho
A 10k pot draws 0.5mA, as pwillard explained.
Add to that the ~3mA for driving the TIP120.
Not a problem, assuming the 12volt supply is 12volt (regulated).
Leo..

Perfect, thank you both for your replies! Really helpful explanations.

Buck converters run cooler, cost more, but introduce noise due to being switching power supplies. Linear regulators brute force it just throwing heat, are much cheaper and quieter electrically. If your circuit is sensitive to noise, like, say, an audio signal amplifier, big linear regulators with big heat sinks are preferred. I’m about to solder a regulator ground tab to my aluminum enclosure… Fingers crossed.

I got interested in this because a 9V 3A power brick wired straight to Vin and Gnd on a Nano smokes the AMS1117-5 regulator on a Nano in under 10 seconds. a little slower on an Uno. The Nano looks to have less heat sink area on the PCB. I’m starting to play with Schottky diodes and bypass capacitors between the barrel jack and the Vin / Gnd pins on the Nano.

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