Powering Arduino with car batteries Presumably, one powers an Arduino board with car batteries for long-term operation away from the power grid.

How can this be done, and what are the most (1) economic, and (2) reliable ways to do this? Specifically, do any additional risks to short the board with an extraneous discharge exist?
Use a switching regulator such as the LM2596. You can get a ready board from eBay for about US$1.



Just set the output voltage to 5&nbsp;V and feed the Vcc input of Arduino; this bypasses the onboard regulator.

The benefit is that unlike the linear onboard regulator, a switching regulator is very efficient which means less consumption and less generated heat on the regulator. An additional benefit is that it can withstand a higher input voltage (about 35&nbsp;V for the specified regulator), just in case the circuit is used in a vehicle that has 24&nbsp;V batteries.

The regulator has already several protections like for short circuiting, overheating, etc.