From: RicArgente@cs.com
Message-ID: <75.10dbac3e.27cdb74e@cs.com>
Date: Tue, 27 Feb 2001 21:07:10 EST
Subject: Re: Lights on - VisionMicro OFF
To: LFrantz@compuserve.com, lancair.list@olsusa.com
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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Hey Jim, thanks much for the electrical lesson!  I'll let you know what I 
find...

Later
Rick   ;-)


In a message dated 02/27/2001 6:17:46 PM Eastern Standard Time, 
LFrantz@compuserve.com writes:

> When the lights come on, there is lots of current flowing around in the
>  wires and through battery, circuit breaker and ground connections.  Lots of
>  current flowing through a poor connection results in a huge voltage drop
>  across that connection leaving little voltage to run a voltage sensative
>  instrument like the VM.  
>  
>  For example, let's assume the landing light draws 10 amps, the VM draws 1
>  amp and somewhere in that circuit that is common to both there is a loose
>  or poor connection that has a resistance of 0.3 ohms.  With only the VM
>  turned on, the voltage drop across the connection is .3 ohms x 1amp = .3
>  volts.  That means that there is still 11.7 volts available to run the VM
>  which is no problem (12-.3=11.7 volts).  But when the landing light comes
>  on, the current is 11 amps (1 amp VM and 10 amp light = 11 amps).  The
>  voltage drop across the bad connection is now .3 ohms x 11 amps = 3.3
>  Volts. Now the voltage available to the VM is only 12-3.3=8.7Volts which is
>  not enough to run the VM properly.
>  
>  With the electrical system and landing lights on, you could use your volt
>  meter to measure the voltage at the VM.  If it is low as I suspect, then
>  measure the voltage drop across the various connections common to both the
>  VM and the landing lights.  I would start at the battery connnections, and
>  work your way up the path that the current takes.  Somewhere along that
>  path you will find a connection that has a significant voltage drop across
>  it. I'm assuming the voltage drop is not due to an undersized wire which
>  could also cause the same problem.
>  
>  If you wish to forward this to the mail list that is OK.
>  
>  Good luck,
>  Jim Frantz
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