Bill;

That is a very interesting read.  Would have been good to know before wiring
my airplane.  I didn't put in a separate switch for alternator field because
'Why should I - cars don't have one'.  I have a pullable breaker which I
occasionally pull when I expect to have the power on with the engine off for
extended periods - like entering flight plans, doing EFIS upgrades, or back
when I did a lot of programming of the EC2.  It hadn't occurred to me that
there could be increased contact resistance in the breaker causing higher
output voltage.

Nor had I considered that there would be high output current from the
alternator during start.  However; I question his argument on this point.
How much current will the alternator put out a cranking speed?  And even if
it is off during cranking; the moment you turn it on once the engine is
running, it senses low voltage (from the drawdown during cranking) and puts
out maximum current for a short time.  Anybody have any real numbers on
this?

Al G

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Sunday, July 26, 2009 6:31 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Charging Systems and Troubleshooting


This has some pretty good "how to" on troubleshooting your charging system.
It is based on a Piper system, but is pretty close to the Nuckolls way.
Also there was a discussion a while back about whether you should turn the
alternator on before starting the engine.  This has a different take on that
subject.

http://www.nflite.com/ChargingSystem.html

Bill B


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