---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 10/25/09: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:16 PM - Re: Need help with desicsion (Bob-tcw) 2. 05:47 PM - Re: Need help with desicsion (ROGER & JEAN CURTIS) 3. 06:23 PM - Re: Need help with desicsion (Bob-tcw) 4. 07:53 PM - Flakey UPS AT GPS/COM (DEAN PSIROPOULOS) 5. 08:43 PM - Re: Flakey UPS AT GPS/COM (Don) 6. 11:08 PM - Confusing (Speedy11@aol.com) ________________________________ Message 1 _____________________________________ Time: 04:16:34 PM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: Need help with desicsion I believe you slipped a zero. 6 awg is 0.4 mOhms per foot so the voltage drop on 4 feet is just under 0.1 volts. An easy rule of thumb to remember is 10 awg wire is 1 milliohm per 1 foot, every three wire sizes doubles the resistance. (so 7 awg would be about 2 milliohms per foot.) -Bob Newman ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Friday, October 23, 2009 11:37 AM Subject: Re: AeroElectric-List: Need help with desicsion > > > At 08:25 AM 10/23/2009, you wrote: >> >>I am running a 60 amp alternator in my system and can't decide which way >>to go with the wire size to the main bus. #8 is good to 57 amps, my max >>continuous load is 45 amps. If I get right up to the 60 amp load for some >>reason this will exceed the wire limits, I will also have a 60 am ANL. >> >>Is the #8 wire a compromise or is it just fine, or should I go up to #6? >>I do have the #6 wire, so it is not a matter of saving $, just the weight, >>the only thing I would need is some lugs. I bought the #6 wire without >>really thinking this through. I want to do this the best way possible, >>not just what will work. So since materials are not the issue which way >>would you guys and gals go. >> >>Thanks for the help, am I over thinking this! > > Assuming that you're alternator b-lead is 4' long, > a 6AWG at 4 mOhms/Ft will drop 60 x .004 x 4 = .96 > volts at full load. If your alternator is an externally > regulated device then the regulator senses BUS voltage > instead of B-terminal voltage and it will compensate > for the voltage drop. However, if internally regulated, > the bus will run about 1.0 volts low during full load > operations. In practice, you'd never be able to realize > that loading because loads on the alternator are a > combination of system requirements + battery recharge > currents. For a 14.2v setpoint, a 13.2v bus wouldn't > significantly stimulate the battery to soak up the > joules it would like to have if the bus were actually > higher. > > If your alternator is externally regulated, then > voltage drops in the b-lead only limit your minimum > speed for full alternator output . . . which at > take-off or cruise settings is not a limiting > factor. > > The trends are moving toward internally > regulated (b-lead sense) and small b-lead feeders > COMBINED with all other wires between the alternator > and battery can stack up voltage drops that will > impact battery recharge performance. This is why > the Z-figures generally show 4AWG or larger for > b-lead feeders . . . and all other fat-wires. > > Having said that, unless your battery is seriously > discharged, these simple-ideas in physics have > little perceivable effect on your operations. > Going to the wire tables is not particularly > useful for fat-wire calculations since their > recommendations are based on temperature rises > that generally fall WELL BELOW that which the > wire will tolerate in your airplane. The hard- > hat consideration is for voltage drop under the > worst case conditions. There are additional > voltage drops to be considered for the full- > up system. > > Know that automobiles tend to use fat-wires that > are a lot smaller than the aviation community > would find acceptable for meeting design goals. > At the same time, except for a severely discharge > battery, automobiles almost never encounter conditions > that exploit the full capability of the > alternator. I've often suggested that if it > were my airplane and the batteries were up front, > I'd craft all the fat-wire paths with 4AWG welding > cable for reasons that are not readily revealed by > praying over the wire table . . . > > > Bob . . . > > > ________________________________ Message 2 _____________________________________ Time: 05:47:46 PM PST US From: "ROGER & JEAN CURTIS" Subject: RE: AeroElectric-List: Need help with desicsion Bob N., I believe you slipped in the wrong direction. #7 AWG is larger than #10 AWG therefore the resistance should be less. Roger -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob-tcw Sent: Sunday, October 25, 2009 7:13 PM Subject: Re: AeroElectric-List: Need help with desicsion I believe you slipped a zero. 6 awg is 0.4 mOhms per foot so the voltage drop on 4 feet is just under 0.1 volts. An easy rule of thumb to remember is 10 awg wire is 1 milliohm per 1 foot, every three wire sizes doubles the resistance. (so 7 awg would be about 2 milliohms per foot.) -Bob Newman ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Friday, October 23, 2009 11:37 AM Subject: Re: AeroElectric-List: Need help with desicsion > > > At 08:25 AM 10/23/2009, you wrote: >> >>I am running a 60 amp alternator in my system and can't decide which way >>to go with the wire size to the main bus. #8 is good to 57 amps, my max >>continuous load is 45 amps. If I get right up to the 60 amp load for some >>reason this will exceed the wire limits, I will also have a 60 am ANL. >> >>Is the #8 wire a compromise or is it just fine, or should I go up to #6? >>I do have the #6 wire, so it is not a matter of saving $, just the weight, >>the only thing I would need is some lugs. I bought the #6 wire without >>really thinking this through. I want to do this the best way possible, >>not just what will work. So since materials are not the issue which way >>would you guys and gals go. >> >>Thanks for the help, am I over thinking this! > > Assuming that you're alternator b-lead is 4' long, > a 6AWG at 4 mOhms/Ft will drop 60 x .004 x 4 = .96 > volts at full load. If your alternator is an externally > regulated device then the regulator senses BUS voltage > instead of B-terminal voltage and it will compensate > for the voltage drop. However, if internally regulated, > the bus will run about 1.0 volts low during full load > operations. In practice, you'd never be able to realize > that loading because loads on the alternator are a > combination of system requirements + battery recharge > currents. For a 14.2v setpoint, a 13.2v bus wouldn't > significantly stimulate the battery to soak up the > joules it would like to have if the bus were actually > higher. > > If your alternator is externally regulated, then > voltage drops in the b-lead only limit your minimum > speed for full alternator output . . . which at > take-off or cruise settings is not a limiting > factor. > > The trends are moving toward internally > regulated (b-lead sense) and small b-lead feeders > COMBINED with all other wires between the alternator > and battery can stack up voltage drops that will > impact battery recharge performance. This is why > the Z-figures generally show 4AWG or larger for > b-lead feeders . . . and all other fat-wires. > > Having said that, unless your battery is seriously > discharged, these simple-ideas in physics have > little perceivable effect on your operations. > Going to the wire tables is not particularly > useful for fat-wire calculations since their > recommendations are based on temperature rises > that generally fall WELL BELOW that which the > wire will tolerate in your airplane. The hard- > hat consideration is for voltage drop under the > worst case conditions. There are additional > voltage drops to be considered for the full- > up system. > > Know that automobiles tend to use fat-wires that > are a lot smaller than the aviation community > would find acceptable for meeting design goals. > At the same time, except for a severely discharge > battery, automobiles almost never encounter conditions > that exploit the full capability of the > alternator. I've often suggested that if it > were my airplane and the batteries were up front, > I'd craft all the fat-wire paths with 4AWG welding > cable for reasons that are not readily revealed by > praying over the wire table . . . > > > Bob . . . > > > ________________________________ Message 3 _____________________________________ Time: 06:23:50 PM PST US From: "Bob-tcw" Subject: Re: AeroElectric-List: Need help with desicsion oops. I sure did. ,#7 awg would be 1/2 mohm..#13 is 2 mohms . my bad -Bob Newman ----- Original Message ----- From: "ROGER & JEAN CURTIS" Sent: Sunday, October 25, 2009 8:43 PM Subject: RE: AeroElectric-List: Need help with desicsion > > > Bob N., > > I believe you slipped in the wrong direction. #7 AWG is larger than #10 > AWG > therefore the resistance should be less. > > Roger > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob-tcw > Sent: Sunday, October 25, 2009 7:13 PM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Need help with desicsion > > > I believe you slipped a zero. 6 awg is 0.4 mOhms per foot so the > voltage > drop on 4 feet is just under 0.1 volts. > > An easy rule of thumb to remember is 10 awg wire is 1 milliohm per 1 foot, > every three wire sizes doubles the resistance. (so 7 awg would be about 2 > milliohms per foot.) > > -Bob Newman > > > ----- Original Message ----- > From: "Robert L. Nuckolls, III" > To: > Sent: Friday, October 23, 2009 11:37 AM > Subject: Re: AeroElectric-List: Need help with desicsion > > >> >> >> At 08:25 AM 10/23/2009, you wrote: >>> >>>I am running a 60 amp alternator in my system and can't decide which way >>>to go with the wire size to the main bus. #8 is good to 57 amps, my max >>>continuous load is 45 amps. If I get right up to the 60 amp load for >>>some > >>>reason this will exceed the wire limits, I will also have a 60 am ANL. >>> >>>Is the #8 wire a compromise or is it just fine, or should I go up to #6? >>>I do have the #6 wire, so it is not a matter of saving $, just the >>>weight, > >>>the only thing I would need is some lugs. I bought the #6 wire without >>>really thinking this through. I want to do this the best way possible, >>>not just what will work. So since materials are not the issue which way >>>would you guys and gals go. >>> >>>Thanks for the help, am I over thinking this! >> >> Assuming that you're alternator b-lead is 4' long, >> a 6AWG at 4 mOhms/Ft will drop 60 x .004 x 4 = .96 >> volts at full load. If your alternator is an externally >> regulated device then the regulator senses BUS voltage >> instead of B-terminal voltage and it will compensate >> for the voltage drop. However, if internally regulated, >> the bus will run about 1.0 volts low during full load >> operations. In practice, you'd never be able to realize >> that loading because loads on the alternator are a >> combination of system requirements + battery recharge >> currents. For a 14.2v setpoint, a 13.2v bus wouldn't >> significantly stimulate the battery to soak up the >> joules it would like to have if the bus were actually >> higher. >> >> If your alternator is externally regulated, then >> voltage drops in the b-lead only limit your minimum >> speed for full alternator output . . . which at >> take-off or cruise settings is not a limiting >> factor. >> >> The trends are moving toward internally >> regulated (b-lead sense) and small b-lead feeders >> COMBINED with all other wires between the alternator >> and battery can stack up voltage drops that will >> impact battery recharge performance. This is why >> the Z-figures generally show 4AWG or larger for >> b-lead feeders . . . and all other fat-wires. >> >> Having said that, unless your battery is seriously >> discharged, these simple-ideas in physics have >> little perceivable effect on your operations. >> Going to the wire tables is not particularly >> useful for fat-wire calculations since their >> recommendations are based on temperature rises >> that generally fall WELL BELOW that which the >> wire will tolerate in your airplane. The hard- >> hat consideration is for voltage drop under the >> worst case conditions. There are additional >> voltage drops to be considered for the full- >> up system. >> >> Know that automobiles tend to use fat-wires that >> are a lot smaller than the aviation community >> would find acceptable for meeting design goals. >> At the same time, except for a severely discharge >> battery, automobiles almost never encounter conditions >> that exploit the full capability of the >> alternator. I've often suggested that if it >> were my airplane and the batteries were up front, >> I'd craft all the fat-wire paths with 4AWG welding >> cable for reasons that are not readily revealed by >> praying over the wire table . . . >> >> >> Bob . . . >> >> >> >> >> > > > ________________________________ Message 4 _____________________________________ Time: 07:53:27 PM PST US From: "DEAN PSIROPOULOS" Subject: AeroElectric-List: Flakey UPS AT GPS/COM I know there are several folks out there who have UPS AT (now Garmin) Apollo GX-60/65, SL-30/40 avionics. I've followed the installation instructions very carefully but I'm still experiencing some issues that seem attributable to the connector pins on the unit occasionally not making good contact with the connector/sockets on the tray. My GX-65 has to have a pin grounded in order for the unit to NOT go into simulation mode. The wonderful consequence of this DUMB design decision is that unit has been entering SIM mode occasionally after I turn the avionics on. I can make it stop if I turn it off and joggle the radio in the tray a little and then turn the unit on again. I checked the connectors on the back of the tray and they are not loose and they are installed on the backside of the tray per the instructions. There don't seem to be any loose pins and none of the wires are loose, broken or otherwise unattached. I've installed the unit in the tray with the cam per instructions taking care not to over tighten but to make sure the cam is as tight as seems possible. I was also getting a COM radio failure on the same unit but the radio tested out fine, after jiggling the antenna connector on the back of the tray I stopped getting the failure but am wondering how long that will last. Question, is anyone else experiencing this? Is there a cure? Having to jiggle a $3000.00 piece of equipment back and forth in the tray to make it work is outrageous. Please advise! Bob is there any similarity in the connector pin world to the correlary that a switch will fail sooner if not used (due to the contacts not rubbing over each other and keeping corrosion at bay)? UPS AT uses DB-15 and DB-30 connectors with crimp on gold plated pins/sockets which I used with tefzel wire grounded to a forest of tabs. I have a 2 gauge tefzel wire from the tabs to the battery ground. Please advise. Thanks all.... Dean Psiropoulos N197DM RV-6A Tampa bay area ________________________________ Message 5 _____________________________________ Time: 08:43:56 PM PST US From: "Don" Subject: RE: AeroElectric-List: Flakey UPS AT GPS/COM Dean, My Garmin 480 had the same problems. The solution was to push the unit in a little harder before the cam is turned. The units must seat all the way to work and the cam can't do that if the unit is not in far enough first. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of DEAN PSIROPOULOS Sent: Sunday, October 25, 2009 7:32 PM Subject: AeroElectric-List: Flakey UPS AT GPS/COM I know there are several folks out there who have UPS AT (now Garmin) Apollo GX-60/65, SL-30/40 avionics. I've followed the installation instructions very carefully but I'm still experiencing some issues that seem attributable to the connector pins on the unit occasionally not making good contact with the connector/sockets on the tray. My GX-65 has to have a pin grounded in order for the unit to NOT go into simulation mode. The wonderful consequence of this DUMB design decision is that unit has been entering SIM mode occasionally after I turn the avionics on. I can make it stop if I turn it off and joggle the radio in the tray a little and then turn the unit on again. I checked the connectors on the back of the tray and they are not loose and they are installed on the backside of the tray per the instructions. There don't seem to be any loose pins and none of the wires are loose, broken or otherwise unattached. I've installed the unit in the tray with the cam per instructions taking care not to over tighten but to make sure the cam is as tight as seems possible. I was also getting a COM radio failure on the same unit but the radio tested out fine, after jiggling the antenna connector on the back of the tray I stopped getting the failure but am wondering how long that will last. Question, is anyone else experiencing this? Is there a cure? Having to jiggle a $3000.00 piece of equipment back and forth in the tray to make it work is outrageous. Please advise! Bob is there any similarity in the connector pin world to the correlary that a switch will fail sooner if not used (due to the contacts not rubbing over each other and keeping corrosion at bay)? UPS AT uses DB-15 and DB-30 connectors with crimp on gold plated pins/sockets which I used with tefzel wire grounded to a forest of tabs. I have a 2 gauge tefzel wire from the tabs to the battery ground. Please advise. Thanks all.... Dean Psiropoulos N197DM RV-6A Tampa bay area ________________________________ Message 6 _____________________________________ Time: 11:08:06 PM PST US From: Speedy11@aol.com Subject: AeroElectric-List: Confusing Hey guys - I have a puzzling question for you. At least it's puzzling to me. I'm studying my downloaded engine monitor data and it appears that when I transmit on the radio that I get an amperage spike and a simultaneous voltage drop. That makes sense - but, at the same time my OAT readings drop several degrees F and then recover to normal after the transmission. The OAT probe is in a NACA duct on the bottom of the wing and it is exposed to the bent wire radio antenna. Is it possible that the signal from the radio antenna is affecting the OAT readings when the radio signal hits the OAT probe? Confused in Daytona Beach, Stan Sutterfield ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.