X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao103.cox.net ([68.230.241.43] verified) by logan.com (CommuniGate Pro SMTP 5.3c4) with ESMTP id 4032079 for flyrotary@lancaironline.net; Sun, 20 Dec 2009 10:55:35 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.43; envelope-from=alventures@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao103.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20091220155459.LKIA26337.fed1rmmtao103.cox.net@fed1rmimpo03.cox.net> for ; Sun, 20 Dec 2009 10:54:59 -0500 Received: from BigAl ([72.192.128.205]) by fed1rmimpo03.cox.net with bizsmtp id KTuy1d00B4S1t5C04TuywP; Sun, 20 Dec 2009 10:54:58 -0500 X-VR-Score: -30.00 X-Authority-Analysis: v=1.1 cv=hxRkenI+XOLoHPjz51PhBd6+pm8nOe1puOOeXS7yE/Y= c=1 sm=1 a=62EDHGUDnBYA:10 a=Vegc0WxVmH5BHtpNDyThtA==:17 a=Ia-xEzejAAAA:8 a=N8B9JuSIAAAA:8 a=Onn9qQcjIifqX91qORMA:9 a=FgA06KWrbLvlV3wCd9Pv6P85hSUA:4 a=EzXvWhQp4_cA:10 a=xXeMbL9VJNRoKs5E-CAA:9 a=Giyn-qSCGovTYNkU7csA:7 a=Mtv2HlsNIuGNjKhEWzrKSG42_aoA:4 a=Vegc0WxVmH5BHtpNDyThtA==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Real Life No Alternator test Date: Sun, 20 Dec 2009 07:55:33 -0800 Message-ID: <7EBCBE2B26974C8FAAD613DA2E90D8C1@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01CA8149.CEE28D70" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Importance: Normal Thread-Index: AcqBFwrdhcydJrpwQjmxivFjIqvW+wAcwNog In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_0006_01CA8149.CEE28D70 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Dave; =20 Regarding the varying, or higher charging voltage, I've had similar behavior. I've determined that a possible cause is the difference where = you are measuring the voltage, and what the regulator is seeing. I provide = the field current from a separate source, having undone the internal = connection from the alternator output. You may have a similar setup. That means = that any resistance - voltage drops - from the battery to the alternator = field, will result in the regulator seeing a lower voltage, and increasing the output. =20 I have two potential contact resistance points in that circuit; the = battery contactor, and a pullable breaker that I use to turnoff the field = current if I want. A couple of weeks ago when I started up the voltage (at the = EM2) was reading over 15V, and triggering the over limit light. After a = couple of resets of the breaker, and a couple of shutdowns (turning off battery contactor), the voltage settled down at 14-14.5. =20 I'm not fully convinced the contacts were the problem, but I think it likely. May be relevant to your situation. =20 Early this year I had replaced the voltage regulator after seeing high voltage. Next time I'll replace the pullable breaker or the battery contactor. =20 (I bet the skiing at mammoth was great, and the weather beautiful.) =20 Al =20 =20 =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard Sent: Saturday, December 19, 2009 5:52 PM To: Rotary motors in aircraft Subject: [FlyRotary] Real Life No Alternator test =20 I have been having an intermittent and slowly worsening problem with = high voltage. Over most of the last 30 hrs or so it settled in around 14.6 = or 14.7 volts. But on yesterday's flight home from Mammoth I noticed it hovering around 15V and some of my avionics were acting up, so I decided = to do a little alternator out experiment. =20 I turned off the alternator and all unnecessary draw - radio, strobes, = Blue Mountain EFIS, electric AI. I kept on the engine instrumentation, transponder, music (a most critical item given the beauty of the = sunset), audio panel, rocky mountain microencoder, and trio auto pilot (also = allowing me to more fully enjoy the flight). I was showing 8 amps to run the = engine bus (coils and injectors). =20 =20 With my 33 amp hour Panasonic SLA battery I flew for 45 minutes and 200 miles over the Sierras, passing dozens of airports, and into the LA = basin before it got dark enough that I decided to turn the lights on. The = plan was to turn the alternator back on when the voltage dropped below 11.5 = volts but it never dropped below 11.9V. It did charge at a brisk 60amps when = I turned the alternator back on so there couldn't have been too much time left. Still, that did quite a bit of confidence building regarding the ability to carry on in the event of an alternator failure. =20 I also set a personal record for the most beautiful and clear sunset I = have seen while flying. I could see San Nicholas Island from over 150 miles away. =20 Time to install a spare alternator. --=20 David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net ------=_NextPart_000_0006_01CA8149.CEE28D70 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Dave;

 

Regarding the varying, or higher charging voltage, I’ve had similar behavior.  I’ve = determined that a possible cause is the difference where you are measuring the voltage, = and what the regulator is seeing.  I provide the field current from a = separate source, having undone the internal connection from the alternator = output. You may have a similar setup. That means that any resistance – voltage = drops – from the battery to the alternator field, will result in the regulator = seeing a lower voltage, and increasing the output.

 

I have two potential contact = resistance points in that circuit; the battery contactor, and a pullable breaker = that I use to turnoff the field current if I want.  A couple of weeks ago = when I started up the voltage (at the EM2) was reading over 15V, and triggering = the over limit light.  After a couple of resets of the breaker, and a = couple of shutdowns (turning off battery contactor), the voltage settled down = at 14-14.5.

 

I’m not fully convinced the = contacts were the problem, but I think it likely.  May be relevant to your situation.

 

Early this year I had replaced = the voltage regulator after seeing high voltage.  Next time I’ll = replace the pullable breaker or the battery contactor.

 

(I bet the skiing at mammoth was = great, and the weather beautiful.)

 

Al

 

 

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Saturday, December = 19, 2009 5:52 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Real = Life No Alternator test

 

I have been having an intermittent and slowly worsening problem with high voltage.  Over most of the last 30 hrs = or so it settled in around 14.6 or 14.7 volts.  But on yesterday's flight = home from Mammoth I noticed it hovering around 15V and some of my avionics = were acting up, so I decided to do a little alternator out = experiment.

 

I turned off the alternator and all = unnecessary draw - radio, strobes, Blue Mountain EFIS, electric AI.  I kept on the = engine instrumentation, transponder, music (a most critical item given the = beauty of the sunset), audio panel, rocky mountain microencoder, and trio auto = pilot (also allowing me to more fully enjoy the flight). I was showing 8 amps = to run the engine bus (coils and injectors). 

 

With my 33 amp hour Panasonic SLA battery I = flew for 45 minutes and 200 miles over the Sierras, passing dozens of airports, and into the LA basin before it got dark enough that I = decided to turn the lights on.  The plan was to turn the alternator back on = when the voltage dropped below 11.5 volts but it never dropped below = 11.9V.  It did charge at a brisk 60amps when I turned the alternator back on so = there couldn't have been too much time left.  Still, that did quite a bit = of confidence building regarding the ability to carry on in the event of an alternator failure.

 

I also set a personal record for the most = beautiful and clear sunset I have seen while flying.  I could see San = Nicholas Island from over 150 miles away.

 

Time to install a spare = alternator.


--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net http://RotaryRoster.net

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