Pete-
Is this approach noisy at all? Can you hear any high-pitched whine in
the
audio system? Any insight into the switching converter (such as the
power it
can handle, where it is available, cost, etc). Either way, this could
come
in handy too, possibly for backup of the Ducati during flight. After
all, in
the 914, the pumps need to keep spinning and the time electrical
problems
crop up always seems to be at the most in-opportune time, like between
land
masses :).
I will be giving up the pad which would have been for the second
alternator, in order to place the oil regulator for the constant-speed
prop.
The front alternator alternative would require cowl mods, so it might be
an
easy two-wire switch-in solution for at least or just the pump, if our
infamous regulator fails (and assuming open diodes and not shorted scr's
is
the normal failure mode).
Backup also requires a reliable stator. Has anyone ever had the charging
coils go out?
Regards,
Greg
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Peter
Zutrauen
Sent: Tuesday, January 21, 2014 10:38 AM
Subject: Re: Europa-List: Ducati rectifier/regulators ... a different
perspective
Just as an aside......
Fwiw for my other homebuilt I added a custom tiny alternator (actually a
high-current model airplane 3-phase brushless permanent magnet
"outrunner"
motor) I decided to not fully load the alternator constantly with these
wasteful regulators (in an effort to save power as well as longevity)
but
instead let the rectified bus voltage climb to whatever the alternator
will
produce (~27V at cruise RPM). I then use a high-frequency switching
convertor (a potted single module) to convert down to 13.4V for
charging
the battery. The convertor comes on line at an input voltage > 17V.
Seems
to work well so far.
Cheers,
Pete
A239
On Tue, Jan 21, 2014 at 1:06 PM, nigel_graham@m-tecque.co.uk
<nigel_graham@m-tecque.co.uk> wrote:
I have followed this discussion with great interest and with an
increasing
sense of D=E9j=B1 vu.
When the issue of regulator/rectifier failures occur withing the Rotax
community, the standard fix seems to be to simply replace like with like
(at
elevated Rotax pricing) and fly on until the next unit fails.
Up until about five years ago, nearly all modern Japanese motorcycles
used
the same technology as that found on the Rotax 91x series engines,
permanent-magnet generators controlled by SCR rectifier/regulators. It
may
come as some surprise that for an industry renowned for precision and
reliability, nearly all of these major motorcycle manufactures have at
some
time, been plagued by problems with their SCR based rectifier/regulators
failing and burning out alternators and wiring, cooking batteries and in
extreme cases, squirting unregulated AC into the wiring loom and blowing
up
ECUs. It was just such a failure that "sparked" my interest :-(
Known as "Shunt Regulators" the SCR technology runs extremely hot and
requires more cooling air than modern styling and space allows.
The solution was a move towards MOSFET controlled regulators and the
numerous web-based one-make discussion groups were full of information
and
advice on the reasons for failure, the benefits of the change and
practical
advice on how to convert.
It was by trawling these groups that I was able to build up a good
understanding of how these R/Rs worked, what was causing the problem and
what the potential solution might be. I compiled what I considered to be
the
best informed snippets of information into the attached document.
The first half gives an overview of a typical design of an SCR
Rectifier/Regulator for use on a permanent-magnet generating system and
the
second half discussed the relative merrits of SCR versus MOSFET.
It would be interesting to know which technology the the after-market
Schicker and Silent-Hektic R/Rs use.
Nigel
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