Mailing List lml@lancaironline.net Message #54185
From: Gary Casey <casey.gary@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: Re: voltage variation
Date: Tue, 12 Jan 2010 08:02:26 -0500
To: <lml@lancaironline.net>
Randy,
You'll probably get more expert answers than mine, but here is what I would do if I didn't have an oscilloscope handy:  Measure the voltage on the field wire from the regulator to the alternator.  With no load and the battery voltage over 14 it should read a low voltage - 2 or 3 maybe, but not zero.  When you add load it should go up and with the battery voltage pulled down to 12.5 it should read full battery voltage.  If the field is full on and the voltage is still low there must be a problem with the alternator.  But before changing that I would check all the electrical connections between the alternator and battery, especially the alternator ground.  That would mean loosening and retightening all the bolts including the alternator mounts.  Being bolted to the engine usually provides an adequate ground, but is there a chance that it is not?
Gary


Just a quick question from a peon 235 driver,
 
 I am running a suzuki 55 amp alternator which i have removed the voltage 
regulator. I am using the old ford style regulator mounted on the firewall. 3 
weeks ago I was taxiing in and my voltage dropped so low 10v that my dynon 
glass panel went black and then came back on.
 I turned everything off and the voltage went to 14.7. Turn on the landing 
lights and loaded it up and it was back to 10 v or so.
 I replaced the voltage regulator as that was a cheap fix. It is still 
happening. The voltage hovers around 14.5v with little load and drops to 12.5 
or so  with a load at cruise.
 
 Is this just a simple case of the alternator needing rebuild. It has around 
400 hours or so..
 
 Randy Snarr
 N694RS
 235/320

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