Mailing List flyrotary@lancaironline.net Message #46421
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: RE: [FlyRotary] Over Voltage?
Date: Sun, 14 Jun 2009 20:11:42 -0400
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>

Hi Dave,

 

My alternator voltage  normally shows as 13.8 – 14.4 volts and has for years.  Even with the battery off line it reads a nominal 14 volts (don’t ask how I know {:>)).   Right after shut down my battery voltage will often read around 13 Volts – but will generally decay to around 12.7-12.8 volts.

 

Not knowing what your nominal voltage is – hard to say what the cause may be.  By the way, my alternator is the stock Mazda Rx-7 which has continued working well for over 10 years.

 

I would say to confirm you fancy talking voltmeter’s findings first with a separate voltohmeter, before anything else.  I have a “Low Voltage” warning light that started coming on after a number of years – turns out the circuit controlling it had slowly drifted out of calibration over the years.  An adjustment of a Pot put it functional again.

 

My personal opinion is that I would carefully monitor the voltage, but I would try a few local flights just to see if the situation continued.

 

Let’s know what you find

 

Ed

 


From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Sunday, June 14, 2009 7:21 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Over Voltage?

 

Today retuning from my flight my voltmeter started to complain "check voltage".  The bus voltage was reading between 14.2 - 14.6 volts.  Right after shut down the battery voltage was reading 13.3 volts.

 

Is this a sign of impending over voltage failure of the regulator? 

I am using the stock 70 amp alternator.  Do I need to replace it right away?  Use an external regulator?  Is it safe to watch it for another flight or two and see what it does?  Is it possible that oil mist could have gummed things up a little and spraying some contact cleaner into the alternator might do the trick?

 

How much voltage is too much before I need to land right away?

Thanks all.


--
David Leonard

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

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