REFLECTOR: Wiring

[Laurence Coen]

Ron,

Before you get to worried about toasting your alternator while cranking I' like to tell you my story. I flew a Cherokee 180D for 18 years.  It didn't have a split master so the alternator was always on line and the field had a non-pullable breaker.  Never caused a problem.  The contention in the article was that alternator would have a 200A overload during cranking.  The starter is taking 200A so we should be able to disconnect the battery and have a perpetual motion starter.  First the engine is rotating at about 30 to 40 RPM with the starter.  At idle the alternator can't make more than 1/3 it's rated output and the engine would be spinning at 10 to 15 times faster.  In addition the voltage regulator also limits the current output  to 60A for a 60A alternator.  I had two alternator failures.  The first was the regulator which was of the mechanical vibrator type.  It was replaced with a solid state device and never caused any more problems.  The second was a diode failure that was a broken wire caused by vibration.  The diode still tested good but the lead was broken off.  The tachometer had about 1800 hours on it when this happened.  The alternator was rebuilt and was still in service a thousand hours later trouble free.

Larry Coen
N136LC


From: Ron N Velocity XLFG 
Sent: Friday, February 17, 2012 11:41 AM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Wiring


Simple note .
I have been chasing a engine issue on my Lt1 for months . I found the problem
to be a loose buss bar contact. Some times it would make good contact 
other times not at all. The bolt was barley snug .  I found it after reading the 
article on the Alternator (Thanks To who ever sent it  very enlightening. I will be changing
may alternator circuit to include a relay cut off of the field circuit  when starting the engine)
A must from what I read .
  The article also  talked about resistance of Switch contacts.
So I was doing some checking on the conductivity of a set of wires and bingo.
Found a contact that had some resistance that should have not been there.
So I put a new crimp on the wire made sure all of the other  screws were tight and now 
it runs much better. Frustrating how one wire crimp can cause me so much 
frustration.

Make sure all your life  connections are solid  Thanks Reflectorits

Ron


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