On Sun, 03 May 2015 15:15:00 -0400, J Burns
wrote:

On 5/3/15 9:06 AM, wrote:
In the aircraft world they are referred to as a 14 volt system, with
12 cell battery systems referred to as 28 volt.

I imagine that's because automobile systems were developed to power a
starter from a battery, and, in the days of generators, you could be
down to 12 volts on the road.

Aircraft electrical systems were designed primarily to power equipment
aloft, without much variation in engine speed.
And the avionics need to be designed to function optimally at the
prevailing operating voltage. Something designed with a 12 volt
maximum voltage wouldn't last long at 14 - and in the aircraft world
they are nothing if not precise when it comes to specs.

Automobile owners, if told their system was a 14 volt system, would be
all bent out of shape to find the resting state voltage to be only
12.6.