---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Fri 06/14/13: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:45 AM - Erratic voltage output (MacDonald Doug) 2. 08:12 AM - Re: Erratic voltage output (FLYaDIVE) 3. 02:57 PM - Re: Erratic voltage output (Roger Lee) ________________________________ Message 1 _____________________________________ Time: 07:45:12 AM PST US From: MacDonald Doug Subject: RotaxEngines-List: Erratic voltage output I'm having an erratic voltage output problem on my 912UL powered CH-701.- =0A=0ATo try and fix the problem I have replaced the voltage regulator and verified I have no loose connections in the electrical system.- Even wit h a new regulator I am still getting the same voltage spikes when at full p ower.- At idle and during run-up the voltage reading on my analog VDO vol tmeter is rock solid.- It indicates about 14 volts once up off of idle po wer 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 flyi ng with a light electrical load, the digital voltmeter tops out at just ove r 14 volts but drifts around as low as 13.7.- If I put on my nav and stro be lights the voltage drops to 13.3-13.6 range but the needle on the analog meter continues to vibrate the same.=0A=0AThe only other components (besid e the regulator) in the electrical system I can think of which might be cau sing the voltage spikes are the capacitor or a problem with the actual alte rnator 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 legi timate issue and not simply a display problem.=0A=0AI'm pretty good at chas ing electrons but this issue has me stumped.- Anyone have any ideas what could be causing my erratic voltage output?=0A=0ADoug MacDonald=0ACH-701, N orthwestern Ontario ________________________________ Message 2 _____________________________________ Time: 08:12:59 AM PST US Subject: Re: RotaxEngines-List: Erratic voltage output From: FLYaDIVE Doug: 1. Being that your Analog Gauge is vibrating indicates that you may have a Vibration issue... Such as being in need of a Dynamic Prop Balance. 2. For a battery to charge you need 13.8 to 14.2 VDC - Less than that you are not charging. 3. Being that the voltage is correct at idle and fluxuates at cruise speed could be an indication of (a) A heat issue or (b) A vibration issue or (c) Both 4. There are a few funky issues with Rotax and their internal voltage production - Too Bad Rotax has never solved this problem. *Barry* *"Pilots think they are mechanics, because they can buy tools at Home Depot."* On Fri, Jun 14, 2013 at 10:44 AM, MacDonald Doug wrote: > 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 > > * > > * > > ________________________________ Message 3 _____________________________________ Time: 02:57:40 PM PST US Subject: RotaxEngines-List: Re: Erratic voltage output From: "Roger Lee" Hi Doug, This happens when the ground is poor. Try a test. leave the existing ground in place and install a more direct and solid ground from the battery, to the engine to the wiring ground block for the plane. I have had numerous issues like this I cured by installing a much more direct and solid ground. It won't hurt to try it and rule it out as a factor. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center - Heavy Maint. 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