powering an Arduino in a car

Thread Starter

Deen198

Joined Feb 17, 2022
8
Hello,

I know this topic has been discussed many times. But after spending hours searching on the web I just couldn't find a definite answer to my problem.

So I would like to continuesly power an arduino (or ATmega328) in my car to monitor 12V signals.
Here is the schematic:
scetch.jpg1. First off all, would this work? I know software better than hardware :)

2. And second, What would be the safest way to power the arduino whilst keeping the power consumption as low as possible.


2a. Should I just take a car usb car charger? (how do I know it's a good and safe one, design and componentwise?)

2b. Should I create something myself? I found these regulators which seem suited for this; https://www.infineon.com/dgdl/Intro...4.pdf?fileId=5546d46146d18cb40147440c4569288d

3. Power consumption is apparently much lower on 3.3V compared to 5V on the arduino. As the Arduino will always be on, I don't want the battery to drain in 2 weeks. How could I power this with 3.3V?

Any help would be appreciated
 

MisterBill2

Joined Jan 23, 2018
13,689
A linear regulator will be the simplest option, but a switching regulator will be more efficient. What is the value of leaving the Micro powered when not using the car for a long time?
Using a separate battery that is isolated from the vehicle electrical system but gets charged when the car is running will avoid the dead battery problem. It will also isolate the micro from vehicle electrical system noise and spikes.
 

Thread Starter

Deen198

Joined Feb 17, 2022
8
A linear regulator will be the simplest option, but a switching regulator will be more efficient. What is the value of leaving the Micro powered when not using the car for a long time?
Using a separate battery that is isolated from the vehicle electrical system but gets charged when the car is running will avoid the dead battery problem. It will also isolate the micro from vehicle electrical system noise and spikes.
The value when powered is around 35mA on 5V, which is quite high. Therefore is was looking at 3.3V, and maybe also reducing the clockspeed from 16mhz to 8.

How would I make such a system with a separate battery? could you share a sketch? thanks
 

MrChips

Joined Oct 2, 2009
27,651
Step #1
Check the AUX 12V outlet or USB charger port to see if power is still available when the car ignition switch is off.
If there is no power then you might have to find a spare fused line from the 12V battery.

However, there are other solutions.
Firstly, you want to check power consumption of your Arduino or any other MCU options.
Investigate all power saving modes. Many MCUs can be powered down to consume less than 1μA @ 3.3V

Your safest option is to power your MCU from a Li-ion cell and recharge it when required. You can design a system that will run for months or years on one power charge. You can also have the cell charged when the car is running.
 

KeithWalker

Joined Jul 10, 2017
2,604
Hello,

I know this topic has been discussed many times. But after spending hours searching on the web I just couldn't find a definite answer to my problem.

So I would like to continuesly power an arduino (or ATmega328) in my car to monitor 12V signals.
Here is the schematic:
1. First off all, would this work? I know software better than hardware :)

2. And second, What would be the safest way to power the arduino whilst keeping the power consumption as low as possible.


2a. Should I just take a car usb car charger? (how do I know it's a good and safe one, design and componentwise?)

2b. Should I create something myself? I found these regulators which seem suited for this; https://www.infineon.com/dgdl/Introduction to Automotive Linear Voltage Regulators BR-2014.pdf?fileId=5546d46146d18cb40147440c4569288d

3. Power consumption is apparently much lower on 3.3V compared to 5V on the arduino. As the Arduino will always be on, I don't want the battery to drain in 2 weeks. How could I power this with 3.3V?

Any help would be appreciated
What 12V signals are you monitoring?
Do you need to monitor them continuously or could you sample them at intervals?
If you can sample them, how often do they need to be checked?
If the time between samples is long enough, it would be possible to put the processor into sleep mode between the samples.This would greatly reduce the power requirements.
 

MrSalts

Joined Apr 2, 2020
2,596
I would get an Arduino Nano Every with onboard SMPS stepdown regulator - it can handle up to 21v supply input. 200uA quiescent power on the monolithic voltage regulator.
https://store-usa.arduino.cc/products/arduino-nano-every?selectedStore=us
Here is the datasheet on the regulator installed on the Arduino Nano Every
https://www.monolithicpower.com/en/...eet/lang/en/sku/MPM3610GQV-Z/document_id/2090

Don't confuse the Arduino Nano Every with the Nano. Better processor, better design (all components on one side so you can mount the Nano to another board with its castellated holes, better regulator. And, cheaper ($12 for genuine Arduino - not available as a clone, yet).

Also, don't run the relay coil directly from the Arduino.

you may not need a relay, just get a transistor ir Mosfet.
 
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