I'm considering a project that would involve connecting a very
low-power Computer on Module and an LCD display inside a vehicle.  The
vehicle will not be driven or possibly even started for an entire week
so what I'm wondering is if anyone knows how long I might have on a
fairly standard car battery if I'm using ~35 Watts from the LCD and
the CoM?

My goal is a full 7 days so if I need to use a lower power LCD so be
it.  Otherwise I will need to find a different way to power the
device.

And yes, the CoM will be running Linux.

-- 
Donovan Niesen