"allow high voltage" .... hopefully the battery would do it's best to soak
it up (with the alternator's limited current generating capacity).
Cheers,
Pete
On Tue, Jan 21, 2014 at 2:31 PM, houlihan <houlihan@blueyonder.co.uk> wrote
:
> Hi David.
>
> One thing to bear in mind is that there are, as I understand it, several
> modes of failure of the Ducatti unit the most benign being that it just
> stops charging the battery and feeding the services.
> This is as you describe and as I also suffered ( why does this happen mid
> channel?) but I believe it can fail and possibly allow high voltage DC or
> AC onto the bus giving your expensive radio and other clever stuff a real
> hard time !
>
> In the UK there is very little difference in cost between the Schicke and
> the Ducatti they are very similar in size and the wiring is only slightl
y
> changed , one wire not connected, and the generator fail light has to
> become an LED.
>
> Tim
>
>
> On 21 January 2014 19:13, David Joyce <davidjoyce@doctors.org.uk> wrote:
>
>> davidjoyce@doctors.org.uk>
>>
>>
>> Nigel, Fascinating and impressively erudite. You have totally convinced
>> me that the way all new builders should go is with a Mofset bit of kit.
>> However my personal solution is to take the odd Ducatti at sale price o
ff
>> anyone not planning to fit them and fly with a spare! In 1000hrs I have
had
>> one failure. That was inconveniently 1/3 way between Holland and Clacton
,
>> but there was enough juice in the battery to get me all the way home wit
h a
>> bit of thoughtful systems management. I currently fly with Rowland's
>> spurned new Ducatti in my spares department under pax seat, but am prepa
red
>> to offer a modest price for another unwanted Ducatti!
>> Regards, David
>>
>> "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=E0 vu.
>>> When the issue of regulator/rectifier failures occur withing the Rotax
>>> community, the standard fix seems to be to simply replace like with lik
e
>>> (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/regulator
s
>>> failing and burning out alternators and wiring, cooking batteries and i
n
>>> extreme cases, squirting unregulated AC into the wiring loom and blowin
g 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 pract
ical
>>> 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 an
d
>>> what the potential solution might be. I compiled what I considered to b
e
>>> 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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