Aircraft wiring with 12v ignition?

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
6,307
Location
Saline Michigan
Markproa,

14V DC is the approximate voltage of the system with the alternator running and charging your battery. Yes, your battery is a 12 Volt battery, but that is actually 12.6V if measured with most volt meters. Put a big load on it, like cranking your engine and it can go below 10V and some electronics will reboot when that happens. Your 12 V battery will not recharge at 12V or 12.6V, but will require a voltage on the order of 14V to recharge, which is about where the regulator for your charging system is set. So in airplanes we call it a 14V system, because that is where we run the system. And in cars, they call it a 12 V system, because that is about what the car runs at with the lights on and the engine not running. Same battery chemistry and same regulator functions, different names. Rrrrr.

Could be worse, we could get into why we use magnetic headings on the ground and with ground based navaids and airport winds, but true headings for wind aloft, or why we use mph for airport wind on the ground and knots for winds aloft, or why we used to use Fahrenhiet temperature on the ground and Celsius aloft. OK, in the States we finally fixed that one...

Billski
 

cluttonfred

Well-Known Member
HBA Supporter
Joined
Feb 13, 2010
Messages
7,009
Location
World traveler
Getting back to the topic, I was thinking that a push-pull battery disconnect could be used as a manual master switch and/or emergency disconnect or even one of the key-type units could be modified to operate remotely.

remote disconnect.jpg
key disconnect.jpg
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
12,252
Location
Memphis, TN
As long as the amp draw is not too high when you close one of the race emergency switches it will work. It will arc so high amp switching will eat it up. It’s really designed to stay connected until an emergency.
 
Group Builder
Top