[HH] Portable Pi Power

[Tom Metro]

Make Magazine explains how to power a Raspberry Pi from an 18V power
tool battery:
http://makezine.com/projects/portable-pi-power-raspbery-pi-to-go/

The author first tried a simple linear regulator, which overheated, then
an off-the-shelf car adapter, which didn't have a stable enough output
to keep the Pi from crashing. Finally he tried a custom circuit using a
Murata's OKI-78SR-5/1.5-W36-C, which puts out 5-volts at 1.6 amps. The
OKI-78SR series are switching regulators designed to be almost drop-in
replacements for the old 78xx linear regulators, requiring minimal
support components.

 -Tom