---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 09/24/17: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:37 AM - Re: Voltmeter & Ammeter normal ranges (andymeyer) 2. 04:09 AM - Re: Unsupported coax length (Bill Watson) 3. 05:38 AM - Re: Re: Voltmeter & Ammeter normal ranges (Sebastien) 4. 05:56 AM - Re: Voltmeter & Ammeter normal ranges (user9253) 5. 06:28 AM - Re: Voltmeter & Ammeter normal ranges (Charlie England) 6. 06:36 AM - Re: Re: Voltmeter & Ammeter normal ranges (Sebastien) 7. 06:59 AM - Re: Voltmeter & Ammeter normal ranges (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 02:37:36 AM PST US Subject: AeroElectric-List: Re: Voltmeter & Ammeter normal ranges From: "andymeyer" Are your lines to/from the shunt twisted pair? If not, you may be getting loop current from elsewhere in the system. Not sure how much, but worth a check. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473114#473114 ________________________________ Message 2 _____________________________________ Time: 04:09:27 AM PST US Subject: Re: AeroElectric-List: Unsupported coax length From: Bill Watson No answers here, just what I did: I ran my RG400 through grommets but also ran several other wires along with it. They were bound together with the waxed thread stuff at roughly 12" to 18" intervals. It seems to me that combining wires in a bundle provided a certain level of support. I think some of the written guidelines suggest the same. My guess is that RG400 alone thru grommets is just fine as well. On 9/23/2017 8:58 PM, Paul Eckenroth wrote: > Looking for advise on what the max acceptable unsupported horizontal > length of RG400 coax might be. I have 23" between fuselage ribs and > was planning on running the coax through a grommet in the tooling > holes but then started questioning if this was good practice. So > opinions are requested. > > Thanks > Paul --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 3 _____________________________________ Time: 05:38:37 AM PST US From: Sebastien Subject: Re: AeroElectric-List: Re: Voltmeter & Ammeter normal ranges They aren't my lines but I'll check :). I'm also going through the install manual for the 120 and looking for documentation on the alternator and voltage regulator. Thanks for the idea Andy. Sebastien > On Sep 24, 2017, at 11:34, andymeyer wrote: > > > Are your lines to/from the shunt twisted pair? If not, you may be getting loop current from elsewhere in the system. Not sure how much, but worth a check. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=473114#473114 > > > > > > > > > ________________________________ Message 4 _____________________________________ Time: 05:56:43 AM PST US Subject: AeroElectric-List: Re: Voltmeter & Ammeter normal ranges From: "user9253" As long as system voltage is above 13, it is impossible for current to flow out of the battery. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=473122#473122 ________________________________ Message 5 _____________________________________ Time: 06:28:38 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Voltmeter & Ammeter normal ranges I did get the pic, but honestly didn't pay any attention to it. Just took a look. Note that voltage never drops below 14V. So the charging system is working great. My personal opinion is that you have too much of the wrong information, and not enough needed information. Where is the shunt wired into the system? Is it really a shunt, or a hall effect sensor? What does the current do with *all loads except the battery removed*? (Yeah, I know you can't do that since the monitor is embedded in the EFIS.) How about with everything turned off except the EFIS/monitor? A typical shunt has, IIRC, a 50 millivolt full scale output to the meter. Assuming it's a 60A shunt the output at the currents you're measuring would be wandering around a few thousandths of a volt. That is a very small signal, and as others have hinted, relatively easy to impress noise onto the lines. And the most minute variations in resistance of any connection anywhere in the sense circuit could cause large variations in voltage at the meter. I seriously doubt that there's anything wrong with the charging system. There *may* be issues with the sensor and/or its wiring, but if it were my plane, I'd almost feel like I was getting too much knowledge for my own good. :-) On Sat, Sep 23, 2017 at 11:14 PM, Sebastien wrote: > I'm guessing from some of the responses I'm getting that the picture I > attached did not go through. The apparent current flow out of the battery > is not from a high load. We're talking a 40-60 amp alternator powering 10 > amps worth of instruments and radios. The load cycles from -2 to +2 amps at > least 50 times over the course of a 1 hour flight and it's not because > someone's hiding under the floorboards flicking the lights on and off :). > > I'll try attaching the engine analyzer data again tomorrow. I did manage > to check a few minutes of data from an identical analyzer in a different > aircraft and while it did cycle up and down a bit, it never showed > negative. > > Sebastien > > On Sep 24, 2017, at 04:50, ashleysc@broadstripe.net wrote: > > Hi Sebastien; > Flow out of the battery is not abnormal and will happen whenever your > aircraft consumes more power than its alternator can generate. It is not > generally a signal to land immediately, but to reduce power consumption > (like turn off the landing lights). > Cheers! Stu. > > ------------------------------ > *From: *"Sebastien" > *To: *aeroelectric-list@matronics.com > *Sent: *Saturday, September 23, 2017 4:09:48 PM > *Subject: *AeroElectric-List: Voltmeter & Ammeter normal ranges > > I am doing the test flying on a friend's RV-6 and as part of the > preparation I set up the engine monitor (Dynon 120) to display the > following on the voltmeter and ammater: > > Voltmeter: Red below 10V, Yellow 10-13.8V, Green 13.8V-14.5V, Red > 14.5V > Ammeter (wired to show current flow in to the batter): Red < 0A, Green 0 - > 5A, Yellow 5-30A, Red > 30A. > > Battery is an Odyssey PC680 AGM. Alternator and regulator unknown, came > with the kit from Van's 10-20 years ago. My guess is Plane Power. > > First Question: Do the ammeter settings seem reasonable? Obviously any > discharge (<0A) is red as indicative of a problem that requires landing > ASAP. Normal charge after a start has been observed to be < 5A within a > minute after start, a hard start or low battery would obviously make this > worse so I set green as 0-5A but don't have any good basis for this. Same > for the yellow and red bands. I want the yellow band to indicate that a > long time in this area is a problem, and red to be an immediate problem. > Normally once the battery has been charged after a start the value should > be zero so perhaps the green band should be 0-1A? What charge level going > into this battery would indicate an immediate problem (red band)? > \ > After first flight the low current alarm was constantly going off so I > changed it from <0 to <1. Second flight had similar but not as frequent > problem so I was going to lower it a little more but then I was able to > download the engine monitor data to Savvy and WOW is it fantastic being > able to look at graphs of engine data. I have no idea what normal would > look like but here is a snap shot of the second flight: > > You can see the battery amps wander between -2 to +2, with excursions to > -3 +3 later in the flight (during large engine power changes). > > Second Question: Is this behaviour indicative of: > > A. Normal operation > B. Sensor problem > C. Charging system or battery problem > D. Something else > > Thank you all for your input. > > ________________________________ Message 6 _____________________________________ Time: 06:36:11 AM PST US From: Sebastien Subject: Re: AeroElectric-List: Re: Voltmeter & Ammeter normal ranges Exactly. Joe could you please confirm that the jpeg below is visible? If so it's obvious that while the voltage seems to be moving around a tiny bit, it never gets to the point which would allow the amperage shown. It's always above 14V. Also I checked some data with the engine shut down and while the amperage still wanders around it's 1 A or less (-5.5 to -6.5 A) On Sun, Sep 24, 2017 at 5:54 AM, user9253 wrote: > > As long as system voltage is above 13, it is impossible for current to > flow out of the battery. > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=473122#473122 > > ________________________________ Message 7 _____________________________________ Time: 06:59:53 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltmeter & Ammeter normal ranges At 06:09 PM 9/23/2017, you wrote: >I am doing the test flying on a friend's RV-6 and as part of the >preparation I set up the engine monitor (Dynon 120) to display the >following on the voltmeter and ammater: > >Voltmeter: Red below 10V, Yellow 10-13.8V, Green 13.8V-14.5V, Red > 14.5V >Ammeter (wired to show current flow in to the batter): Red < 0A, >Green 0 - 5A, Yellow 5-30A, Red > 30A. Assuming you do monitor bus voltage and have active notification of low voltage, then there is no operational value for monitoring battery current. Battery ammeters in airplanes were a carry-over from the terrestrial vehicles where the minus-zero-plus instrument in the battery charge/discharge line was the simplest single monitor of system health during normal vehicle operations. The ammeter would be expected to show a heavy recharge rate right after cranking the engine . . . or after a jumper cable start on a dead battery. After some interval of normal operation, the battery accepts less and less recharge energy and the needle migrates toward zero. Under normal ops (votlage about right, battery charged) the needle would rest at or just slightly above zero. If generator output was insufficient (low engine rpm, high system loads, regulator voltage drifting downward, generator failing) the needle would present some value below zero. While truly an analog instrument, its BEHAVIOR was closer to 'digital' in that it was never intended to be READ so much as observed as a go/no-go panel instrument. Ammeters of all types are of little to no value as sources of operational data in flight. Ammeters in the battery lead are pretty much useless when compared to an accurate voltmeter paired with active notification of low voltage. Calibrating a battery ammeter with alarm settings will be an exercise in futility. Suggest you move the ammeter sensor to the alternator b-lead and eliminate any alarm functions from this reading. The ammeter is most useful as a maintenance tool for diagnosing why the VOLTAGE is low and/or the LOW VOLTS warning light was illuminated in the air. 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