I recently ran across this thread and thought to myself "awesome, i'll just run with my ebus on at all times, that makes sense!" However, I've been doing some more reading and found this in the VPX user manual, which seems to indicate that having the ebus on at all times may not always be very desirable:
"If you have a primary alternator and a secondary (backup) alternator only
one alternator (field wire) should be powered on at a time. Therefore, we
refer to one alternator as the primary and the other as the secondary. If
both are on simultaneously, they do not equally ?contribute? to powering
the loads. The one whose voltage regulator is set to the highest voltage
will draw all the current (sometimes called current hogging), possibly
overloading the alternator"
What does everyone think about the above consideration?
I have the following thoughts/questions:
1. Assuming a backup alternator was being 'seen' since it had the higher voltage and was overloaded, this would simply mean it couldnt keep up with the demand of the electrical system and therefore the battery would be depleted over time. This would manifest itself as a gradual voltage drop of a running system, correct?
2. Assuming a system with the Nuckols Z13/8 scheme, for example, that means essentially having two nonadjustable voltage regulators in having the "ford regulator" plus the built-in regulator on the plane power alternator, right? I wonder what the expected voltage output of each of these is..
3. There might be an interesting situation where in the Z13/8 the endurance bus would see higher voltage from the backup alternator but perhaps the main bus would see higher voltage from the main alternator due to the diode that exists between the main and endurance bus. Is it possible that two different buses could in fact 'see' two different alternators as described?
Here is a sample Z13/8 with a couple modifications, for reference to ponder these questions:
http://n42bu.com/SharedFiles/Z13-8R2-N42BU.png