REFLECTOR: Bus, Battery & Electrical Instrumentation

[Keith Hallsten]

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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