REFLECTOR: Bus, Battery & Electrical Instrumentation

[Terrence Miles]

Lar, Keith,
I'm not the smartest bunny in the woods on this...but Larry could be mean 
retifier and not diode w/ regards the field windings?  Also Ammeter could 
help in flight as you download to show actual load being pulled off the 
source into the users and back to ground.  In the event of an alternator out 
this might help you look around some more to make sure that all is off.  
Knowing the draw of your min in-flight load can only be done w/ an ammeter.
Terry

>From: "Keith Hallsten" <KeithHallsten at quiknet.com>
>Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
>Subject: RE: REFLECTOR: Bus, Battery & Electrical Instrumentation
>Date: Sun, 19 Jun 2005 13:02:04 -0700
>
>Larry,
>
>
>
>What was the voltage on the bus when you had the bad alternator diode?  I
>would expect that it would be lower than usual, and a voltmeter would show
>that an issue was present.  If the voltage was, say, 14 volts the battery
>would have charged.
>
>
>
>My point is that a voltmeter will tell you everything you need to know as a
>pilot.  An ammeter might be handy when troubleshooting, which should be 
>done
>on the ground.
>
>
>
>Keith
>
>
>
>
>
>   _____
>
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>Behalf Of Laurence Coen
>Sent: Sunday, June 19, 2005 7:44 AM
>To: Velocity Aircraft Owners and Builders list
>Subject: Re: REFLECTOR: Bus, Battery & Electrical Instrumentation
>
>
>
>Keith,
>
>
>
>I experienced such a failure mode on my old Cherokee once.  Alternators
>generally have three separate windings, each with there own diodes.  Metal
>fatigue broke a lead off a single diode.  The alternator made power, but 
>not
>quite enough.  As a result it would come real close to floating the load 
>but
>not enough to recharge the battery.  It took about a month to kill the
>battery.  The second time the battery died I pulled the alternator and 
>found
>the problem.
>
>
>
>Larry Coen
>
>N136LC
>
>----- Original Message -----
>
>From: Keith <mailto:KeithHallsten at quiknet.com>  Hallsten
>
>To: 'Velocity Aircraft <mailto:reflector at tvbf.org>  Owners and Builders
>list'
>
>Sent: Saturday, June 18, 2005 1:57 PM
>
>Subject: RE: REFLECTOR: Bus, Battery & Electrical Instrumentation
>
>
>
>Al,
>
>If your alternator stops producing, the voltage on the bus powered by the
>ammeter will instantly drop to whatever the battery(s) tied to that bus 
>will
>support.  That cannot be more than 12 volts or so.  Therefore, a low-volts
>alarm set at 12.5 volts will instantly warn of alternator failure.  That's
>why I don't think an ammeter is necessary.  I am not aware of any failure
>mode for an alternator that will result in low amperage without
>corresponding low voltage.
>
>Keith
>
>
>
>
>   _____
>
>
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>Behalf Of Al Gietzen
>Sent: Friday, June 17, 2005 11:35 PM
>To: 'Velocity Aircraft Owners and Builders list'
>Subject: RE: REFLECTOR: Bus, Battery & Back Order
>
>
>
>   What voltage do you all trigger the low voltage
>
>warning?  I am guessing that since alternator produce 14V and the
>
>battery is at 12, simplistically it should be set to 13V or so, taking
>
>the middle.  Is there a standard value that is the "industry standard"?
>
>
>
>My engine monitor will read bus voltage and the current from the 
>alternator.
>I can set the alarm limit for low current output (probably something lower
>than what it takes to just run the engine) to give early detection of low
>alternator output.  Possibly one reason for an ammeter.
>
>
>
>Al
>
>
>   _____
>
>
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