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1. 11:10 PM - Re: Erratic voltage output (Paul Grimstad)
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| Subject: | Erratic voltage output |
We have been experiencing wild fluctuations on the amperage meter, running a
912uls with Dynon 180 EFIS engine monitor. The spikes range from +5 to -6.
Voltage is also high (high 13's), but then it seems to settle down after
takeoff. I thought the high voltage maybe because we just installed a new
battery.
We also just installed a new voltage regulator and when we grounded the
plane and took a look at the condition we found the two power leads going
into the regulator were completely melted and the heat was starting to melt
the plastic mounting socket on the Ducati voltage regulator. We replaced the
spade connectors on the main power leads and replaced the wiring socket
plug-in connector as well.
We had heard that the Rotax engine electronic system is very sensitive to
the requirement of the ground connection, so additionally we ran a 10ga
copper wire from the base lug on the voltage regulator to the negative
terminal connecting stud at the battery/airframe. This has not solved the
problem. I flew 7hours last weekend and near the end of the flight time, I
noticed the amp gauge still jumping up and down.
I have spoken with several knowledgeable Rotax guys and both asked me if I
ran the ground from the base of the voltage regulator directly to the engine
block?
So, this afternoon I removed the wire socket plug connector and inspected
the wire ends and crimped connectors. There was no sign of heat damage, so I
reconnected the primary connection plug. I made up another ground wire with
soldered wire ends and waterproof shrink tubing. I then installed the new
ground wire from the mounting bolt on the base of the voltage regulator
directly to the engine block. Tomorrow I will run the engine and see if the
problem is solved.
Hope this helps, I will let you know how it goes.
Paul Grimstad,
Team RV12
Portland, OR
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Carl
Sent: Saturday, June 15, 2013 1:25 PM
Subject: Re: RotaxEngines-List: Erratic voltage output
Hi Doug
You stated you have no loose contacts, you could have a poor contact. Two
years ago I had an intermittent charging problem that took two day to trace.
It was in an in-line fuse holder, the rubber coated ones that take ATC
fuses. The fuse looked fairly normal but when I cut the holder open it was
corroded and burnt. Replaced problem gone.
Carl
----- Original Message -----
From: MacDonald Doug <mailto:dougsnash@yahoo.com>
Sent: Friday, June 14, 2013 10:44 AM
Subject: RotaxEngines-List: Erratic voltage output
I'm having an erratic voltage output problem on my 912UL powered CH-701.
To try and fix the problem I have replaced the voltage regulator and
verified I have no loose connections in the electrical system. Even with a
new regulator I am still getting the same voltage spikes when at full power.
At idle and during run-up the voltage reading on my analog VDO voltmeter is
rock solid. It indicates about 14 volts once up off of idle power and my
digital voltmeter show about 13.6 Volts. Once I apply takeoff power the
analog voltmeter needle starts to vibrate wildly plus and minus about 1-2
volts and the digital voltmeter becomes unstable. If I am flying with a
light electrical load, the digital voltmeter tops out at just over 14 volts
but drifts around as low as 13.7. If I put on my nav and strobe lights the
voltage drops to 13.3-13.6 range but the needle on the analog meter
continues to vibrate the same.
The only other components (beside the regulator) in the electrical system I
can think of which might be causing the voltage spikes are the capacitor or
a problem with the actual alternator coils. I thought the problem may have
been a bad analog gauge but given that the digital readings are also erratic
I believe it to be a legitimate issue and not simply a display problem.
I'm pretty good at chasing electrons but this issue has me stumped. Anyone
have any ideas what could be causing my erratic voltage output?
Doug MacDonald
CH-701, Northwestern Ontario
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