Depending on the electrical load you are running you likely won't get
14 when running. Especially if you turn on the landing light, pitot
heat etc. A new alternator is really not that expensive but you can
test some other things first. As others have mentioned, you want to
check the grounds. Is the voltage consistant in flight or does it
bounce around? Anyone with a fuel injected engine should put buying
something like an EDM high on their priority list. As a side benefit,
such a device will show you voltage at all times so you can track it
durin the flight if its not holding steady.

-Robert


On Feb 16, 1:41*pm, Mike Harvey Mike.Harvey.
wrote:
Hello, *I own a 65 m20e with a io360. *Recently been experiencing noise
on com1 and have read about low voltage being a problem with nav/com's.
I have a king ki 165 for both com1 and com2. *I've tried to diagnose the
problem and it appers that my alternator isn't charging the batter
correctly nor is it bringing the system bus up to 14volts. *I've
noticed this via a volt meter to the 12 volt(car type) adatper(although
i don't know if this is the correct procedure) and I've also made notes
of the bus voltage before starting and after shutdown on a long flight
and it went from 13.5 volts to 12.2 volts(enging off). *Does this seem
like it could be a low voltage noise from a alternator not charging
correctly. *If so has anyone had experience repairing alternators on
m20e. *I would imagine a new one would cost around 1K. *But I don't
know.

Thanks

Mike

--
Mike Harvey