how to get a clean 12v Car battery supply to power up my arduino?

I'm doing an arduino project,and I HAVE TO to power the Arduino off the car's battery, I can't connect it through lighter connector and i need it to be hidden. I’m using an Arduino Mega R3.

I heard how the voltage of a car battery can spike and fluctuate while running and how it can get up to 14 volts. I can’t use a USB charger because I’m planning using a class D amplifier to sound purposes that needs up to 4A of current. I’m using a 2x100W TPA3116 amplifier .

I read a buck converter or similar can do the job, do you think this can work?

[http://www.dfrobot.com/index.php?route=product/product&path=70_119&product_id=752#.UfKJTEnnOxU]https://www.dfrobot.com/product-752.html#.UfKJTEnnOxU]http://www.dfrobot.com/index.php?route=product/product&path=70_119&product_id=752#.UfKJTEnnOxU](https://www.dfrobot.com/product-752.html#.UfKJTEnnOxU)

And if not this, what else do you think I can do to use the car battery as a power supply for my arduino?

The Arduino has a built-in 5V regulator and is rated to operate from 7V to 20V. I have an Arduino running in a vehicle off the (nominal) 12V with no problems. You can get into trouble if you “drop” a lot of voltage across the regulator while drawing “extra” current but if you are not powering extra stuff from the Arduino’s 5V power supply you should be fine.

You might get a reset if the voltage drops when you start the car, but the battery may not drop down to 5V and depending on your application it may be OK if the processor resets when you start the car.

I can’t use a USB charger because I’m planning using a class D amplifier to sound purposes that needs up to 4A of current. I’m using a 2x100W TPA3116 amplifier .

Presumably, the audio amplifier will be running directly from the 12V? FYI - You can’t get 100W without a higher power supply (or very low impedance).* Does that amp have a voltage-boosting power supply? Do you know if it’s a bridge amplifier? You also can’t get 2x100W from a 25W voltage converter…

  • Power (Watts) = V2/R

That’s RMS voltage, not peak-to-peak. So that gives you about 5VRMS from 14.4 or (10VRMS from a bridge amplifier) without counting the voltage-loss across the amplifier.

I'd recommend to use some kind of LC filter and a TVS diode installed right near Arduino to filter high voltage spikes which are very likely top be present in a car 12V lines. Buck converter is not necessary.

DVDdoug:
I have an Arduino running in a vehicle off the (nominal) 12V with no problems.

Is it connected directly to the battery?

DVDdoug:
Presumably, the audio amplifier will be running directly from the 12V?

I’ll use a boost converter to have a power supply of 24V for the amplifier. The arduino is just sending a control signal to a relay to activate or deactivate that supply. This is ‘the diagram’: http://prntscr.com/mgytll

I tested all the system with a clean Laboratory DC Power Supply but the only thing missing is to make sure i can use the car battery as my power supply.

I’d recommend to use some kind of LC filter and a TVS diode

I like the TVS diode solution.

DVDdoug:
FYI - You can’t get 100W without a higher power supply (or very low impedance).* Does that amp have a voltage-boosting power supply? Do you know if it’s a bridge amplifier? You also can’t get 2x100W from a 25W voltage converter…

But you can use most of the amplifiers on which 2x100W is written…
For most of them it’s just pure lies…

http://forum.arduino.cc/index.php?topic=7497.15

In this thread you can find good answers... I use arduino in my car with buck converter and TVS and it is running for 3 months for now witout problems