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 increasin
g
> sense of D=C3=A9j=C4=85 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 use
d
> the same technology as that found on the Rotax 91x series engines,
> permanent-magnet generators controlled by SCR rectifier/regulators. It m
ay
> come as some surprise that for an industry renowned for precision and
> reliability, nearly all of these major motorcycle manufactures have at so
me
> 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 an
d
> advice on the reasons for failure, the benefits of the change and practic
al
> 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 t
he
> 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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