I would like to use an Arduino Nano in my campervan and measure Temperature and RV. For the ease of installing would like to use the car battery as power source and connect the battery direct to the VIN of the nano. Car battery voltage fluctuates between 12 and 14.6 Volts. Can this damage the Nano or have an effect on the readings. If yes, what are the ways to solve this?
The recommended value is 7V - 12V.
You can use Car batter which is 12V. The 14V flactuation you see during kHV electrical firing of kHV nozzles.
Suppressing of the noise coming from the the electrical firing of the nozzles would be a callenging job that I had to solve (partial success) while making a Taxi Meter using ATmega328P MCU of UNO/NANO Board,
Here is the problem. The battery voltage and charging voltage are not the problem. The problem is when you start the engine, the starter motor uses a huge amount of current. When that current is suddenly shut off by the starter solenoid switch, a very high voltage is created that feeds directly back to the battery and everything that is connected to it. The battery just acts like a big resistor and doesn't really care because the pulse is short.
You will notice your vehicle has an accessory circuit for all the other devices in the vehicle. That circuit is OPEN while the starter is running and still off when the starter stops, so the accessory devices do not see the turn off pulse from the starter.
So, if you connect your Arduino directly to the battery circuit, is will be subject to the high voltage pulse form the starter system and that will destroy the Arduino, etc.
If you do connect to the battery, you will need to construct a safety circuit to save the Arduino. So search for such a protective circuit.
Thanks for your reply. But the 14.6 volt max is coming from the car dynamo/alternator when driving (charging voltage of the battery). When not driving the voltage drops to 12-12.8 Volt or so.
Thanks, see your point. The nano will be connected to the same powersource as the car radio. This should avoid the puls you explained I guess. Voltage still can reach 14.6 Volts during driving.
That will work fine. Does you vehicle need the key turned to the "acc" position? Easy to forget to do that to keep the Arduino turned on.
Thanks Paul. Actually I connect the Nano the the household battery of my camper (which is
charged by the car dynamo or a solarpanel). And Arduino is always turned on. But is voltage then fluctuates between 12 and 14.6 volts: does it affects my readings? Or damage the
Nano?
You need to read the specification on the nano and its range of input voltages .
Note that if using voltages towards its top end , then driving any sort of load will over heat it .
Easiest quick fix is a couple of capacitors and a 7809 regulator ( as per its data sheet ) to provide your power source , then you know it will be fine .
Thanks. To be on the safe side I now will connect the nano to a car USB poort to at least avoid high voltages. Do not know if that 5 volt output voltage is regulated.
Hmmm … maybe it is ..
The 5v will need connecting to the 5v pin , not the Vin .
Ok, will do. Easiest way to find out USB is regulated or not is to monitor a change in the readings whilst driving and not.
I have had luck doing this.
- With a 1A fuse, connect a diode, anode to +12v, cathode to capacitors in parallel 1000uF(two 470uF @ 35V is okay)/1uF/100nF add bidirectional transorb TVS going to GND.
- Diode cathode to ferrite bead, to buck converter set to 8v, output to Arduino Vin.
chassis GND to ferrite bead then to buck converter GND, then buck converter output GND to Arduino GND..
This is the path that I've used and it's the safest since it should be a clean 5V. Trivial connection using a USB cable to the arduino. Otherwise you will need a regulator on the car 12V for the reasons previously stated.
Thanks a lot. Will first connect the Nano to a car USB and see what happens. If things go wrong I will follow your scheme.
Thanks a lot, will follow this advice and see what happens.
Arduinos were designed for and are are intended for experimentation and learning, often with breadboards. Most important, the boards are not protected against harsh, dirty or electrically noisy environments found in industrial, automotive and other commercial applications. It is unreliable as it is not suitable for industrial, automotive and other commercial operation.
There is many good app notes such as AN2689 by ST on automotive electronics. reading it will help you a lot.
https://www.st.com/resource/en/application_note/cd00181783-protection-of-automotive-electronics-from-electrical-hazards-guidelines-for-design-and-component-selection-stmicroelectronics.pdf
Also take a look at these: Distilled Automotive Electronics Design | Analog Devices and
Transient Voltage Suppression in Automotive Applications
AEC-100 https://media.monolithicpower.com/mps_cms_document/w/e/Webinar_-_Fundamentals_of_AEC-
This will give you an idea of what to expect.
Hint different Arduinos have a different maximum Vin. Read the data sheet.
It's becoming more and more frequent that when we say "arduino" we don't necessarily mean the original Mega328P-based device. The term now spans such a wide range that maybe we need to come up with a new name. e.g., "Arduino-based controller."
Yes, I know this OP specifically refers to the Nano, but it's an issue I've been thinking about more and more often.
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Yes and how many different Nano's are there and which processor do they have. None were designed for the automotive environment that I know about. To me Nano has become a form factor and not even then are they all pinned out where they would be compatible. We both know what the automotive environment is like, but most of the world sees it as a thing with a big 12V battery as did the OP.
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