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Re: Europa-List: Alternator output measurement

Subject: Re: Europa-List: Alternator output measurement
From: Fred Fillinger <fillinger@ameritech.net>
Date: Mon, 28 Apr 2003 16:39:10

 > Does anybody know of a good way to measure the output of the 
alternator to
 > determine how close I am to using up all the capacity of that thing 
under
 > various conditions? I would even like to display that in the aircraft 
on a
 > permanent basis, if it is at all possible.
 >
  > Thanks,
  > Dave
  > A227 Mini U2

A voltmeter across the battery provides a rough idea. For a given RPM,
switching things on should should show the same volts meaning that
whatever available extra current is charging the battery.

A quickie ammeter check is a digital voltmeter, with a 200.0 millivolt 
scale, across the length of the positive battery cable.  That presumes 
alt output is not connected directly to the battery, else move it 
temporarily upstream.  #4 wire will show .00025 mV for each amp for each 
foot.  Of significance is that the cable end farthest from the battery 
is more positive than at the batt.  A larger drop is obtained by idling 
for a while with all loads on, then if the minus sign on the voltmeter 
is showing, observe at what RPM it extinguishes.

Regards,
Fred F.




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