As with the others who have answered, and they are correct...Here are a
couple more tidbits from some old questions I've answered befor:
Quick and dirty for the Rotax mounted alternator/dynamo with external
regulator:
Your field wire (C on the regulator) should read battery voltage with
the engine off. If it does not that's the problem. I have seen folks
run the alternator warning light in series with the C lead to the bus.
If the light bulb fails, you open the field circuit and kill the
regulator. The light circuit must be independent of the C lead
connection to your bus. Read the Rotax installation manual about the
wiring requirements.
Noting that the R and B+ leads (which are tied with the C lead, through
the panel usually) are reading battery voltage not 13.8 volts. The
regulator is not putting out.
Check your 30 amp circuit breaker/fuse coming off the regulator. If all
the above are good, it's the regulator.
Solid state rectifier/regulators put out about 12 volts on the L circuit
and as others have stated, the C circuit and R/B+ should read about
13.8. If the diodes in the regulator fail, your L circuit will put out
a voltage which is about 1.3-1.8 volts less than your C circuit (same as
your bus) and the fail light will still not alert you to a failure as it
is a 12 volt bulb... Just like your car, the alternator light never
comes on with this type failure, only the battery failure is your
indicator unless you monitor your volts and amps.
Rarely do the Rotax coils in the dynamo fail, It is most likely your
regulator.
Bud Yerly
Custom Flight Creations
----- Original Message -----
From: kevin siggery<mailto:ksiggery@mac.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Monday, February 11, 2008 4:08 PM
Subject: Europa-List: 914 alternator/regulator
<ksiggery@mac.com<mailto:ksiggery@mac.com>>
Before we start the nightmare process of replacing the alternator on
914-powered G-ROOV could anyone point us towards possible other
problems with the electrical system recently identified:
Before start, master on, we see I=0 amps, V=11.
Engine off, loaded I=-5, V=11.
Engine running (essentials on) I=-4, V=11
Engine running (full electrical load) I=-5, V=11
Besides the fact we should be seeing 12V from the battery (we are
charging it now) to my non-expert eye this would suggest alternator
problems but strangely, the =91idiot light=92 is not illuminated which
suggests that V (alternator) is greater than V(battery) i.e.: we do
not have an alternator problem (unless the lamp has blown and we are
being misguided).
Alternatively if the regulator is shot one would expect to see V
falling as a function of load (I think) but this is not the
case...although we believe the Ducati regulator is not exactly the
best on the market and prone to quite frequent failure.
We are leaning towards simply swapping out the regulator at this
stage.
Any thoughts most welcome.
thank you
Kevin Siggery
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avigator?Europa-List>
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