The alt light (its a LED, not incandescent) on my Rotax 914 (over 900 hours) has
started to flicker even when at cruise (5000 rpm). It has often flickered when
at low rpm and it always turns full on when the engine is not running. I
have two Hall amp sensors but I can only display one at a time. At cruise, the
amps being delivered by the Rotax system are about 8 to 10 which I what I expect
given the loads turned on. At cruise the amps measured at the battery are
roughly 0, the indication will vary a little from +1 or 2 to 1 or 2 which I
take to be instrument error. The bus voltage is around 13.3 prior to engine
start. After start it slowly climbs to about 14.4 after 20-30 minutes of
cruise.
The aircraft is wired in accordance with AeroElectric Z-16. The battery is an
EarthX ETX680 and its monitoring circuit does not show any problem. I switched
---From lead acid to EarthX ETX36 in 2014 and in March 2017 changed to ETX 680C.
Ive only had this problem recently. Everything was normal at first after
installing
the ETX680C.
In 2014 I added external diodes to supplement the original Ducatti (PN 343620)
regulator/rectifier and a few months later I replaced that Ducatti R/R as the
alt light was illuminating while operation seemed normal. The replacement was
the later model Ducatti (PN 362001) but I left the diodes in place.
I discovered (I think during 2017) that the Rotax system was not delivering a
high
enough voltage to keep the EarthX fully charged. I added a diode in series
in the C lead to boost the voltage. While troubleshooting the charging problem
I changed back to the original Ducatti which has operated fine until the recent
flickering issue.
I cant decide if I have a battery problem or a Rotax/Ducatti problem.
Jim Butcher
Europa XS
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