---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 04/06/04: 22 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:10 AM - Re: alt/battery troubles (Jan de Jong) 2. 05:03 AM - Re: Re: alt/battery troubles (Robert L. Nuckolls, III) 3. 06:11 AM - Firewall penetration questions () 4. 06:14 AM - Single ignition hooked up to two batteries (Mickey Coggins) 5. 07:30 AM - Voltmeter Scaling Module (Rogers, Bob J.) 6. 07:36 AM - Re: Single ignition hooked up to two (Wallace Enga) 7. 08:54 AM - Re: Firewall penetration questions (Robert L. Nuckolls, III) 8. 09:31 AM - Re: Firewall penetration questions (Neil Clayton) 9. 01:36 PM - Re: Firewall penetration questions (Rick Girard) 10. 02:04 PM - Re: Re: alt/battery troubles (Charlie & Tupper England) 11. 04:19 PM - Firewall Fittings () 12. 06:06 PM - Re: Voltmeter Scaling Module (Robert L. Nuckolls, III) 13. 06:31 PM - Re: Re: alt/battery troubles (Rino Lacombe) 14. 07:16 PM - Re: Firewall Fittings (Jim Stone) 15. 07:47 PM - Re: Firewall Fittings (Robert L. Nuckolls, III) 16. 08:11 PM - Re: Round connector with D-sub pins? (N1deltawhiskey@aol.com) 17. 08:11 PM - Re: Round connector with D-sub pins? (N1deltawhiskey@aol.com) 18. 08:18 PM - Out of town for a few days . . . (Robert L. Nuckolls, III) 19. 08:32 PM - Re: Re: alt/battery troubles (Robert L. Nuckolls, III) 20. 08:34 PM - Re: Firewall penetration questions (James E. Clark) 21. 09:24 PM - Re: Re: alt/battery troubles (Robert L. Nuckolls, III) 22. 11:43 PM - Re: Firewall Fittings (Mickey Coggins) ________________________________ Message 1 _____________________________________ Time: 01:10:59 AM PST US From: Jan de Jong Subject: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: Jan de Jong > From battery ground terminal to starter's case measures .3 ohms, as > does anywhere on the engine case. That would mean a loss of .3 volts per amp? The measured resistance cannot be in series with battery and motor or it would not turn at all. Jan de Jong ________________________________ Message 2 _____________________________________ Time: 05:03:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 08:14 PM 4/5/2004 -0500, you wrote: >--> AeroElectric-List message posted by: "James Redmon" > >Parts came in early so I hooked up the two batteries in parallel this >evening. Zzzzing! Engine spins like crazy with a 10.3v bus voltage while >cranking. Tried cranking several successive times (more than 6 times, 10-15 >blades each)...no appreciable degradation of cranking power or voltage. I >think this will work just fine. Now, with the two 17ah bats in parallel, I >have 34ah of energy on tap - quite a comfortable margin, even for a all >electric airplane. > >Question: With the two batteries in parallel, do I have any special charging >concerns - either on the charger, or alternator? > >Thanks all, and especially Bob, for all the help. Nope. There's a lot of myth circulating around about paralleled batteries. It's TRUE that unequal batteries will both accept and deliver energies at what ever they're able to do as individual batteries. Neither battery has any way to sense/react to the presence of other batteries. You could have a dozen batteries in parallel and no single battery will behave any differently than if it were the only battery on line. The only concerns about "balance" between the two batteries is when total cranking current required is greater than the ability of one battery as illustrated in the case you've cited. Here it is NECESSARY to have two batteries of relatively strong capabilities. Let's say one of the two batteries was two years old and could barely get the engine started and you parallel it with a new one. We would EXPECT the new one to take on most of the burden for getting the engine started. In terms of service life for THAT battery, we expect it to degrade faster than it would when teamed with a second new battery. However, in terms of charging or in terms of total energy stored, both batteries will accept and deliver the total of its individual ability irrespective of how many batteries share the energy management responsibilities. If you have occasion to replace your starter, it would be interesting to see if a B&C starter would get the engine going on one battery. Tell you what, if you'll buy a B&C starter and put it on your airplane and don't find it to be a good value replacement for the existing starter, I'll buy it back from you. Bob . . . ________________________________ Message 3 _____________________________________ Time: 06:11:07 AM PST US From: Subject: AeroElectric-List: Firewall penetration questions --> AeroElectric-List message posted by: 1. When installing the Nuckolls/B&C dual ground block through the firewall, is it necessary (or desirable) to take steps to make the penetration more fireproof? Stainless plates on each side? Firestop putty around the brass bolt? 2. What about throttle/mixture/prop cables? These are pretty small holes with a metal fitting on the engine side, but Im just wondering if anything needs to be done to seal them up. Thanks, Dan OBrien ________________________________ Message 4 _____________________________________ Time: 06:14:43 AM PST US From: Mickey Coggins Subject: AeroElectric-List: Single ignition hooked up to two batteries --> AeroElectric-List message posted by: Mickey Coggins Hi, I'm looking for a way to reliably hook up a single electronic control module (engine ignition/computer) to two batteries. I've done a quick sketch and written some text, and I would love to get any feedback on this proposed method of doing this. Please be gentle, I'm quite a novice at this stuff. http://www.rv8.ch/article.php?story=20040406145425120 Thanks, Mickey -- Mickey Coggins http://www.rv8.ch/ #82007 QB Wings/Fuselage ________________________________ Message 5 _____________________________________ Time: 07:30:29 AM PST US From: "Rogers, Bob J." Subject: AeroElectric-List: Voltmeter Scaling Module --> AeroElectric-List message posted by: "Rogers, Bob J." This message is primarily to Mr. Bob Nuckolls, but others may wish to respond as well. At one time back in 2001, the AeroElectric Connection catalog offered a combination Voltmeter/Loadmeter with a Voltmeter Scaling Module ("VSM"), which I purchased (Catalog item VLM-14) for use in my experimental Mustang II kitplane with a Mazda 13B Rotary engine, which comes with an 80-amp alternator. The catalog offered (but I did not then purchase) a separate additional VSM if needed for a second alternator. I now am installing a second alternator (35-amp permanent magnet alternator -not a B&C product), but cannot find a source for the VSM anymore. It seems that neither the AeroElectric Connection nor B&C Specialty carries the product. I have a few questions. 1. From the installation instructions that came with the VLM-14, it appears that use of a double-pole, double-throw switch and a properly sized shunt for each alternator allows me to toggle the input to the Loadmeter back and forth between two alternators. If this is true, why do I need a second VSM? 2. If I do need a second VSM, where can I get one? 3. The catalog literature says "If your airplane is fitted with a permanent magnet alternator, order the 'PM' modification to delete the field voltage test and auto-switching features." Can you please explain why the use of a permanent magnet alternator requires that these two features be deleted? If I have two alternators, one PM and one regular, what is the proper setup? What would happen if I tried to use my VLM-14 with the PM alternator? Voltmeter Scaling Module This message is primarily to Mr. Bob Nuckolls, but others may wish to respond as well. At one time back in 2001, the AeroElectric Connection catalog offered a combination Voltmeter/Loadmeter with a Voltmeter Scaling Module (VSM), which I purchased (Catalog item VLM-14) for use in my experimental Mustang II kitplane with a Mazda 13B Rotary engine, which comes with an 80-amp alternator. The catalog offered (but I did not then purchase) a separate additional VSM if needed for a second alternator. I now am installing a second alternator (35-amp permanent magnet alternator -not a BC product), but cannot find a source for the VSM anymore. It seems that neither the AeroElectric Connection nor BC Specialty carries the product. I have a few questions. 1. From the installation instructions that came with the VLM-14, it appears that use of a double-pole, double-throw switch and a properly sized shunt for each alternator allows me to toggle the input to the Loadmeter back and forth between two alternators. If this is true, why do I need a second VSM? 2. If I do need a second VSM, where can I get one? 3. The catalog literature says If your airplane is fitted with a permanent magnet alternator, order the 'PM' modification to delete the field voltage test and auto-switching features. Can you please explain why the use of a permanent magnet alternator requires that these two features be deleted? If I have two alternators, one PM and one regular, what is the proper setup? What would happen if I tried to use my VLM-14 with the PM alternator? ________________________________ Message 6 _____________________________________ Time: 07:36:27 AM PST US From: Wallace Enga Subject: Re: AeroElectric-List: Single ignition hooked up to two batteries --> AeroElectric-List message posted by: Wallace Enga Mickey, I would suggest that you put separate fuses on each feed line between it's Bus and diode. Use either separate control switches in each feed line or a high quality double pole switch if you want single switch control. For the isolation diodes, use something similar to IR 100BGQ030 Power Schottky for as low as possible forward voltage drop. Use at least 16 AWG wire and 10 Amp fuses. This circuit powers not only the ECM computer, but also the fuel injectors, coil, ignition, ect. Definitely don't want any nuisance trips to OPEN this circuit. The current draw on the circuit will vary with engine power setting --- check with Jan Eggenfellner for the exact numbers. Wally Enga RV7 At 03:11 PM 4/6/04 +0200, you wrote: >--> AeroElectric-List message posted by: Mickey Coggins > > >Hi, > >I'm looking for a way to reliably hook up a single electronic >control module (engine ignition/computer) to two batteries. >I've done a quick sketch and written some text, and I would >love to get any feedback on this proposed method of doing >this. Please be gentle, I'm quite a novice at this stuff. > > http://www.rv8.ch/article.php?story=20040406145425120 > >Thanks, >Mickey > > >-- >Mickey Coggins >http://www.rv8.ch/ >#82007 QB Wings/Fuselage > > ________________________________ Message 7 _____________________________________ Time: 08:54:25 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Firewall penetration questions --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 09:07 AM 4/6/2004 -0400, you wrote: >--> AeroElectric-List message posted by: > >1. When installing the Nuckolls/B&C dual ground block through the >firewall, is it necessary (or desirable) to take steps to make the >penetration more fireproof? Stainless plates on each side? Firestop >putty around the brass bolt? No. >2. What about throttle/mixture/prop cables? These are pretty small holes >with a metal fitting on the engine side, but Im just wondering if anything >needs to be done to seal them up. There are a number of "eyeball" fittings that help with this effort. One example can be seen in photos at: http://www.rvproject.com/20030722.html does anyone on the list have a source to recommend for these fittings? Bob . . . ----------------------------------------- ( Experience and common sense cannot be ) ( replaced with policy and procedures. ) ( R. L. Nuckolls III ) ----------------------------------------- ________________________________ Message 8 _____________________________________ Time: 09:31:44 AM PST US From: Neil Clayton Subject: Re: AeroElectric-List: Firewall penetration questions --> AeroElectric-List message posted by: Neil Clayton I've been going through this very issue in the past few weeks. I ordered those eyeball fitting, and they're a lovely made product, but they expect an RV-like firewall - thin! My 3/8 firewall wouldn't work with them and I had to return them. I'm still trying to find a solution, or at least a workaround. Neil > >2. What about throttle/mixture/prop cables? These are pretty small holes > >with a metal fitting on the engine side, but Im just wondering if anything > >needs to be done to seal them up. > > There are a number of "eyeball" fittings that help with > this effort. One example can be seen in photos at: > > http://www.rvproject.com/20030722.html > > does anyone on the list have a source to recommend for > these fittings? > > Bob . . . > > > ----------------------------------------- > ( Experience and common sense cannot be ) > ( replaced with policy and procedures. ) > ( R. L. Nuckolls III ) > ----------------------------------------- > > ________________________________ Message 9 _____________________________________ Time: 01:36:13 PM PST US From: Rick Girard Subject: Re: AeroElectric-List: Firewall penetration questions --> AeroElectric-List message posted by: Rick Girard Neil et al, You might try Tony Bingelis' book, "Bingelis on Engines", chapter 3, Firewall Preparation, in which he showed how to make nice stainless steel grommet covers with a vice, socket and a plywood form. The same approach should work fine for almost any firewall penetration with a little eye ball engineering. Rick Girard ________________________________ Message 10 ____________________________________ Time: 02:04:21 PM PST US From: Charlie & Tupper England Subject: Re: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: Charlie & Tupper England Jan de Jong wrote: >--> AeroElectric-List message posted by: Jan de Jong > > > > >>From battery ground terminal to starter's case measures .3 ohms, as >>does anywhere on the engine case. >> >> > >That would mean a loss of .3 volts per amp? >The measured resistance cannot be in series with battery and motor or it >would not turn at all. > >Jan de Jong > I think it should be mentioned that measuring resistance of less than a few ohms is not something that is easy to do reliably. Resistance at the contact point of the probe itself can cause significant errors if you aren't very careful & 'deliberate' with the act of probing. It's a lot easier if you're using consumer grade meters to just measure voltage before & after every joint, with a good solid connection to the ground terminal on the battery itself. Attach the probe at the desired test point, then apply voltage to the circuit (including the load) & record the voltage at that point. Move on to the next point & repeat as needed, including the ground side of the load itself & any joints in the ground return path. A noticeable drop across any area except the load itself points to wiring/connection problems. If you see noticeable voltage on the ground side of the load, again, you have wiring/connection problems. Charlie ________________________________ Message 11 ____________________________________ Time: 04:19:51 PM PST US From: Subject: AeroElectric-List: Firewall Fittings --> AeroElectric-List message posted by: Bob et al --- Avery Tools carries a lot of good stuff for our market. They have swivel eyeball fittings to handle 1/8", 3/16" and 1/4" cables through the firewall. They're on the web at www.averytools.com Jim ________________________________ Message 12 ____________________________________ Time: 06:06:29 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Voltmeter Scaling Module --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 10:27 AM 4/6/2004 -0400, you wrote: >--> AeroElectric-List message posted by: "Rogers, Bob J." > >This message is primarily to Mr. Bob Nuckolls, but others may wish to >respond as well. At one time back in 2001, the AeroElectric Connection >catalog offered a combination Voltmeter/Loadmeter with a Voltmeter Scaling >Module ("VSM"), which I purchased (Catalog item VLM-14) for use in my >experimental Mustang II kitplane with a Mazda 13B Rotary engine, which comes >with an 80-amp alternator. The catalog offered (but I did not then >purchase) a separate additional VSM if needed for a second alternator. I >now am installing a second alternator (35-amp permanent magnet alternator >-not a B&C product), but cannot find a source for the VSM anymore. It seems >that neither the AeroElectric Connection nor B&C Specialty carries the >product. Correct. Westach was unable to produce instruments of the necessary quality to support the project. >I have a few questions. > >1. From the installation instructions that came with the VLM-14, it appears >that use of a double-pole, double-throw switch and a properly sized shunt >for each alternator allows me to toggle the input to the Loadmeter back and >forth between two alternators. If this is true, why do I need a second VSM? You don't. The VLM-14 offered a multiplicity of functions. (1) expanded scale voltmeter with autoswitching between main bus and e-bus depending on whether or not the main bus was hot (2) active notification of low voltage, (3) optional press-to-test for monitoring field voltage of a wound field alternator for diagnostic investigations and (4) zero to 100 percent loadmeter that could be switched to multiple shunts; in most cases a maximum of two shunts - one in each of two alternator b-leads. The toggle switch is used for feature (4) only. Autoswitching of the feature (1) was built into the product. >2. If I do need a second VSM, where can I get one? If you have one, that's all you need. >3. The catalog literature says "If your airplane is fitted with a permanent >magnet alternator, order the 'PM' modification to delete the field voltage >test and auto-switching features." Can you please explain why the use of a >permanent magnet alternator requires that these two features be deleted? If >I have two alternators, one PM and one regular, what is the proper setup? >what would happen if I tried to use my VLM-14 with the PM alternator? Not sure what you mean by "regular" alternator. Does it have an external regulator? If so, then you will want to install the components color coded in the installation manual as magenta. If it has an internal regulator, then the magenta wiring and magenta instructions are not applicable to your alternator. The installation instructions: http://www.aeroelectric.com/Catalog/AEC/9021/9021704F.pdf shows addition of a second loadmeter shunt in the b-lead of a second alternator. In this case, your second alternator is a PM device and the two loadmeter shunts would be wired like those shown in Figure Z-13 and switched as shown on page 9 of the instructions. bob . . . ________________________________ Message 13 ____________________________________ Time: 06:31:46 PM PST US From: "Rino Lacombe" Subject: Re: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: "Rino Lacombe" ...........Snip.............. > >Question: With the two batteries in parallel, do I have any special charging > >concerns - either on the charger, or alternator? > > > >Thanks all, and especially Bob, for all the help. > ..........Snip........... > > > If you have occasion to replace your starter, it would > be interesting to see if a B&C starter would get the engine > going on one battery. Tell you what, if you'll buy a B&C > starter and put it on your airplane and don't find it > to be a good value replacement for the existing starter, > I'll buy it back from you. > > Bob . . . I believe that Bob is right on this one. One good 17ah battery should start the engine properly -- it does on mine, every time! Rino ________________________________ Message 14 ____________________________________ Time: 07:16:20 PM PST US From: "Jim Stone" Subject: Re: AeroElectric-List: Firewall Fittings --> AeroElectric-List message posted by: "Jim Stone" I saw some thermoplastic rubber, firewall grommets at www.summitracing.com The item number is MOR-39050. You get several sizes for just 10 bucks. I figure these are a good start, then just cover with the one or two piece covers that are available at Spruce and various other places. Jim Stone ----- Original Message ----- From: Subject: AeroElectric-List: Firewall Fittings > --> AeroElectric-List message posted by: > > Bob et al --- > > Avery Tools carries a lot of good stuff for our market. They have swivel eyeball fittings to handle 1/8", 3/16" and 1/4" cables through the firewall. They're on the web at www.averytools.com > > Jim > > ________________________________ Message 15 ____________________________________ Time: 07:47:08 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Firewall Fittings --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 07:23 PM 4/6/2004 -0400, you wrote: >--> AeroElectric-List message posted by: > >Bob et al --- > >Avery Tools carries a lot of good stuff for our market. They have swivel >eyeball fittings to handle 1/8", 3/16" and 1/4" cables through the >firewall. They're on the web at www.averytools.com Can you give us a link to the parts? I poked around on their website and couldn't find the fittings. Bob . . . ----------------------------------------- ( Experience and common sense cannot be ) ( replaced with policy and procedures. ) ( R. L. Nuckolls III ) ----------------------------------------- ________________________________ Message 16 ____________________________________ Time: 08:11:40 PM PST US From: N1deltawhiskey@aol.com Subject: Re: AeroElectric-List: Round connector with D-sub pins? --> AeroElectric-List message posted by: N1deltawhiskey@aol.com Interested readers, this is a copy of an offline request, FWIW: Just couldn't stand not trying it out. The pins/sockets (machined type as sold by B&C) go into the connector just like the D-sub connectors, and the pins/sockets can be extracted just like the D-subs. As these pins are good for 24-20 ga. wire just like the D-subs. The connector is an AMP 205840-3 female 28 pin version with a 205839-3 male 28 socket connector. In the catalog I saw, they have versions for 3, 8, 28 and 63 pins, or about those numbers, in both female pin/male socket or female socket/male pin versions. For the 28 pin version, the hole size is 1-1/16" with a flange for securing with 4 small screws (they also make a corresponding unflanged type for use without bulkhead mounting). Regards, Doug > just wondering, did you buy the special pin's from AMP or use the one from > the d-subs? ________________________________ Message 17 ____________________________________ Time: 08:11:40 PM PST US From: N1deltawhiskey@aol.com Subject: Re: AeroElectric-List: Round connector with D-sub pins? --> AeroElectric-List message posted by: N1deltawhiskey@aol.com In a message dated 4/5/2004 5:36:35 AM Pacific Daylight Time, lhelming@sigecom.net writes: > You could try using safety wire for holding d-subs together rather than the > tiny screws. That way it cannot vibrate it self loose. Larry, Thanks, but already thought of that -- plan to use the little screws, and safety wire for its intended purpose, as a backup. With the round units, they do not require either of those efforts. Doug ________________________________ Message 18 ____________________________________ Time: 08:18:04 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Out of town for a few days . . . --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" Dee and I are headed for San Antonio for a few days to attend the Southwest Psychological Association convention. Be back in the saddle on Sunday . . . Bob . . . ----------------------------------------- ( Experience and common sense cannot be ) ( replaced with policy and procedures. ) ( R. L. Nuckolls III ) ----------------------------------------- ________________________________ Message 19 ____________________________________ Time: 08:32:09 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 04:03 PM 4/6/2004 -0500, you wrote: >--> AeroElectric-List message posted by: Charlie & Tupper England > > >Jan de Jong wrote: > > >--> AeroElectric-List message posted by: Jan de Jong > > > > > > > > > >>From battery ground terminal to starter's case measures .3 ohms, as > >>does anywhere on the engine case. > >> > >> > > > >That would mean a loss of .3 volts per amp? > >The measured resistance cannot be in series with battery and motor or it > >would not turn at all. > > > >Jan de Jong > > >I think it should be mentioned that measuring resistance of less than a >few ohms is not something that is easy to do reliably. Resistance at the >contact point of the probe itself can cause significant errors if you >aren't very careful & 'deliberate' with the act of probing. It's easier to do with the right equipment. See low resistance measurement techniques discussed in the chapter on grounding. Also, here's an article I did for another program describing a low-ohms adapter for digital multimeters. It has a resolution of 1 milliohm when used with the millivolt scale of most multimeters. See http://www.aeroelectric.com/articles/LowOhmsAdapter.pdf Bob . . . ----------------------------------------- ( Experience and common sense cannot be ) ( replaced with policy and procedures. ) ( R. L. Nuckolls III ) ----------------------------------------- ________________________________ Message 20 ____________________________________ Time: 08:34:01 PM PST US From: "James E. Clark" Subject: RE: AeroElectric-List: Firewall penetration questions --> AeroElectric-List message posted by: "James E. Clark" Bob, et. al., these fittings are available from Bob Avery at Avery Tools. They are in the $25-$30 each. I just purchased a few and recommend them and him. Bob will have them at Sun-N-Fun with a "show special" price. This type requires the drilling/punching of a hole of about 1.1" as I recall. (Don't have the paperwork handy) and they eyeballs come with holes of 3-4 different sizes. The *aluminum* eyeballs can be drilled out to a larger size to accomodate bigger cables of wires. He **ALSO** has the type that starts with the ~1" hole and two small holes for screws that go into a backing plate. The "front" side is then bolted on using four screw that also screw into the backing plate (2 screw hold the backing plate to the firewall and 4 screws attach the "engine side" plate that holds the "eyeball" in. This type comes with steel plate and aluminum balls or steel plate and steel balls. Due to the geometry of the steel "balls", they cannot be enlarged. I looked for pictures on Bob's website but could not find any. These items are though in his latest catalog (near the back). James [SNIP] > > >2. What about throttle/mixture/prop cables? These are pretty > small holes > >with a metal fitting on the engine side, but Im just wondering > if anything > >needs to be done to seal them up. > > There are a number of "eyeball" fittings that help with > this effort. One example can be seen in photos at: > > http://www.rvproject.com/20030722.html > > does anyone on the list have a source to recommend for > these fittings? > > Bob . . . > > ________________________________ Message 21 ____________________________________ Time: 09:24:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: alt/battery troubles --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 10:06 AM 4/6/2004 +0200, you wrote: >--> AeroElectric-List message posted by: Jan de Jong > > > > From battery ground terminal to starter's case measures .3 ohms, as > > does anywhere on the engine case. > >That would mean a loss of .3 volts per amp? >The measured resistance cannot be in series with battery and motor or it >would not turn at all. Good eye! Actually, he was probably making measurements with a garden variety multimeter which probably has a leadwire resistance on the order of .2 ohms. I've just published an article on low resistance measurements at: http://www.aeroelectric.com/articles/LowOhmsAdapter.pdf Used this fixture just today to measure residual resistance in a piece of equipment that faulted and caught fire. The power input leads showed about 200 milliohms to ground. With 28v applied, this produces a current flow on the order of 140 amps for a power dissipation of over 4000 watts in about 1 cubic centimeter of volume. Needless to say, it got pretty hot! Bob . . . ________________________________ Message 22 ____________________________________ Time: 11:43:01 PM PST US From: Mickey Coggins Subject: Re: AeroElectric-List: Firewall Fittings --> AeroElectric-List message posted by: Mickey Coggins >>Avery Tools carries a lot of good stuff for our market. They have swivel >>eyeball fittings to handle 1/8", 3/16" and 1/4" cables through the >>firewall. They're on the web at www.averytools.com > > Can you give us a link to the parts? I poked around on > their website and couldn't find the fittings. Hi, This product does not seem to be in their web catalog, but I've got it in the paper version. I've put a scan on my web site if anyone is interested. http://www.rv8.ch/article.php?story=20040407083459141 Mickey -- Mickey Coggins http://www.rv8.ch/ #82007 QB Wings/Fuselage