Re: Progress

Rick Hole

Alternators can be expected to produce 13-14 volts at anything above idle,
though yours may be a pip-squeak (not saying it is less than adequate for
your need). But battery voltage below 12.2V indicates a discharged battery,
and 11.6 (after being charged) may indicate a worn out battery.

When using a magneto, battery voltage is irrelevant. The mag generates its
own power.



From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
Joseph M Snow
Sent: Tuesday, November 02, 2010 10:55 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Progress

Hi Mike,

You must be running an electronic ignition since magnetos would not require
any amps or volts. I have not yet received a DAR signoff; so, I don't have
a voltage reading during flight. Currently, the volt meter reads between
11.6 and 11.8 volts. Previously, when the alternator was charging, the
voltage read between 12 and 14+ volts, amps - between 2-4 amps at idle to
moderate rpms. Most likely, I believe one of the connections is bad or
wrong. I am using a John Deere, permanent magnet alternator and regulator.
I will post a report when I get it sorted out.

On one occasion during a night flight, I failed to activate the alternator
switch which sends power to the alternator field. The engine was fine
running on magnetos. But, lights got dim, radio transmissions were weak,
nav flags started appearing, etc. So, on that one occasion, I had lost the
alternator and was loosing the battery. Obviously, I survived the

Since my engine runs on a distributor, the engine will continue to run until
about 6 volts. Also, I am not sure I can operate simultanously the
emergency hand pump, fly the airplane and cope with an electrical failure
adequately. So, a backup emergency battery wired to run the ignition and
help transfer the fuel to the header seems prudent to me.


--- On Tue, 11/2/10, Mike Dwyer <mdwyer@...
<> > wrote:

From: Mike Dwyer <mdwyer@... <> >
Subject: Re: [Q-LIST] Progress
To: Q-LIST@... <>
Date: Tuesday, November 2, 2010, 6:59 PM

How many amps does the ignition draw in flight? Mine draws 0 when the
igniton is on but the engine is not running. You could consider the
starting battery is one source of power and the alternator the
second...But you'd want a quick indication of an alternator failure,
which is easy. Alternator working voltage =14, alternator dead,
Mike Q200 N3QP

Joseph M Snow wrote:

Hello Q-listers.

N240JS returned to the airport Monday, 11-1-2010. I have two issues to
resolve before calling the DAR: Alternator not charging and wiring an
emergency backup battery to the backup ignition circuit. Weight and balance
numbers are now within the flight envelope :) With two months to go, I
believe I can fly before the first of 2011.

Joseph Snow
Q2xx, N240JS


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