Ray Andraka wrote:
: If you have a split master, you can approximate the action of the automotive
: starter
: lockout by leaving the alternator side of the master off until the engine is
: started, then
: turning it on. This also has the benefit of not putting the field load (up to a
: couple of
: amperes) on the battery before and during the start.

Another little tidbit on this idea is to wait for a little bit
before energizing the alternator field (with split master). The
alternator actually presents a fairly significant amount of torque load
when putting out full output, which it does briefly when flipped on after
starting. I generally wait until the oil pressure has built up and
stabilized for a bit before flipping on the alternator and watching the
ammeter spike.

I'm not familiar with the PA-23 electrical topology, but someone
who does feel free to correct this thinking. It's probably just like the
PA-24 and older PA-28's, which have a single toggle 'Master' switch. In
this case, that master switch turns on the main contactor relay at the
battery. The problem with this is that if the field stays energized while
the master is turned off, the main power sink and buffer in the system
(battery) is now disconnected. If there wasn't much current going into
it, it's not a problem. If the battery was low, had just been started,
etc, etc, there could be 50A going into the battery that disappears from
the bus. This will cause the "load-dump" transient voltage spike
mentioned before. If the field(s) can be turned off individually, I would
think that's the appropriate technique. Kinda like power
increase/decrease is mixture/prop/throttle and throttle/prop/mixture,
respectively. Electrical startup would be master/starter/alternator field
and shutdown the reverse.

-Cory

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