Go Down

Topic: How To Power Arduino With a 12v Car Battery? (Read 5 times) previous topic - next topic


The Arduino already has a regulator built-in so in theory you could just hook the car battery up to it directly.

I've done this with a standard Duemillanove and it works well for moderate loads (200ma and even up to 500ma). Beyond that you may want to consider a switching regulator. My setup is a boat with an alternator pushing the voltage up to 14.4V when charging.

I believe some credit is deserved for the Arduino design as it includes reverse voltage protection, ripple suppression capacitors and the 7805 power regulator is in itself a very robust chip with several protection schemes included. Keep in mind also that a car battery acts as a gigantic capacitor with excellent noise/ripple suppression.

There are all sorts of things that can cause problems related to power supply (e.g. disconnecting a battery terminal with the alternator spinning) and accordingly there is hardly any limit to what you can add in terms of protection against potential threats. Unless the device you build is very expensive I would not worry too much until real issues surface.

What always makes sense however is to add an inline fuse between the Arduino and the wiring to your battery. This is not to protect your Arduino, but rather the "vehicle" (car, boat, RV, other) which house your device and possibly people as well. A car battery can easily supply several hundred Amps for many seconds and as such fried supply wiring and potential fire is a real threat.

Igor R

Jun 26, 2009, 12:16 pm Last Edit: Jun 26, 2009, 12:19 pm by igorreal Reason: 1
I´ve tested in a car and bike without problems. I´ve only added a varistor between Vcc and Gnd.
How BenF said, the diode for reverse voltage protection and capacitor is already in the pcb.


Igor R.


Absolutely not:  that circuit is doomed.  Sooner or later the car will generate a voltage spike that fries it.

Funny,  I've got a GPS engine powered by the exact same power supply as that arduino (7805) that's been running fine for about 5 or 6 years.

If you've got a way to deal with the heat from the regulator, just plug it up to the arduino's DC jack and go.




What properties varistor did you use, i.e. what was its breakdown voltage. Would 12.7V be too low?



Go Up