---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 11/06/16: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:49 AM - Re: Soldered lap splice has more resistance? (Alec Myers) 2. 10:49 AM - Re: Soldered lap splice has more resistance? (rampil) 3. 11:54 AM - Re: Soldered lap splice has more resistance? (jonlaury) 4. 02:32 PM - Re: Re: Soldered lap splice has more resistance? (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 03:49:06 AM PST US From: Alec Myers Subject: Re: AeroElectric-List: Soldered lap splice has more resistance? If solder had a high resistance, someone would invent a better one that didn't. The conductivity of 60/40 solder is (I read) 153 nanoohm metres. Pure copper is 17 nanoohm metres. This suggests that the very very thin layer of solder that separates the wires in a soldered lap-joint has the same resistance as a layer of copper 9 times as thick. 9 times very vey thin is still very very thin, and negligible compared to the length of the wire itself. I don't believe there's any reason to think the wire-solder interfaces will have any greater resistance than the various solid metal to metal interfaces in a correctly made crimp. > On Nov 5, 2016, at 6:13 PM, Lyle Peterson wrote: > > > Just another ploy to get more money from the uninformed. There is simply too much of this going on but it has been going on for a long, long time. That $756 sounds like a flat rate book figure. It includes removing all the seats, the windshield and the left front wheel. :) An experienced auto electrician will make a ton of money doing that repair all day long. > > This example is why buyers must do their research. Research the dealer and research the contemplated repair. Then do it yourself. > > Lyle > > >> On 11/5/2016 4:51 PM, jonlaury wrote: >> >> Not exactly off-topic, but the question arises from an automotive application. >> >> I have an intermittent START fault that doesn't show up on the dealer computer (3 different dealers). In their investigation, they found some rodent damage to wiring that powers the in-tank fuel pump in a VW Jetta TDI. The dealer wanted $756 to fix it >> I declined. >> >> I retrieved my car, cut out the damage and performed the typical lap splice to the 4 damaged wires, that Bob N. recommends. Specifically, mechanically binding the two lapped wire ends with 2 strands of the conductor, filling the bundle with solder, and covering with heat shrink. It didn't fix the starting fault, but the pump runs fine. >> >> When talking to the dealer again about this, and that I repaired the wiring damage as described, he claimed that soldering the wires together as described would add more resistance to the circuit and could start a fire. I coughed, and sputtered, as my BS meter pegged and exploded. >> >> He said only the VW butt splice method was acceptable. I asked for more details and was told that the VW method uses Crimp and Solder Sealed Butt connectors. I asked if he heard the word "solder" in there. That ended our discussion. >> >> So I think I know the answer to my question, but would like the group's verification. >> >> Thanks, >> JOHN >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=462096#462096 >> >> >> >> >> >> >> >> >> >> > > > > ________________________________ Message 2 _____________________________________ Time: 10:49:09 AM PST US Subject: AeroElectric-List: Re: Soldered lap splice has more resistance? From: "rampil" I think you are dealing with a language issue. You are speaking engineering, and the dealership is speaking income. My advise is to run (away)! (Sent from the Giza plateau where I am field testing my aviation apps ;) ) -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=462107#462107 ________________________________ Message 3 _____________________________________ Time: 11:54:20 AM PST US Subject: AeroElectric-List: Re: Soldered lap splice has more resistance? From: "jonlaury" Thank you all. This battle with VW is far from over and I'm sure they are going to try to hang their incompetent cap on my repair. For fun, I computed the resistance values of my two 1/2" splices from Alec's conductivity specs... total resistance added to the circuit is like 3.5 x 10 to -8, or about 1 billionth of an Ohm. My dog lying on the seat above the splice contributes a greater delta T to the wire than does the 'resistance' of the solder. [Laughing] Read this topic online here: http://forums.matronics.com/viewtopic.php?p=462112#462112 ________________________________ Message 4 _____________________________________ Time: 02:32:13 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Soldered lap splice has more resistance? At 01:53 PM 11/6/2016, you wrote: > >Thank you all. > >This battle with VW is far from over and I'm sure they are going to >try to hang their incompetent cap on my repair. For fun, I computed >the resistance values of my two 1/2" splices from Alec's >conductivity specs... total resistance added to the circuit is like >3.5 x 10 to -8, or about 1 billionth of an Ohm. > >My dog lying on the seat above the splice contributes a greater >delta T to the wire than does the 'resistance' of the solder. [Laughing] > A similar issue arose with a client a few years back who called to ask about 'heat sink grease' to put under a transistor being replaced. He didn't have any 'legacy' products purported to offer exceptional thermal conductivity but needed to expedite the repair. I suggested E6000 . . . just glue the puppy down. He was worried about the relatively low conductivity . . . I reminded him that the two mating surfaces were nearly flat . . . i.e. the gaps to be filled were probably under .001 inches. The conductivity of air (no grease at all) was a whole lot higher than just about anything else he might choose. Even tho the non-traditional filler had 'unimpressive' numbers, they were a whole lot better than air. Further, because the gaps were so thin, the difference between E6000 and the best money could buy was probably impossible to measure. 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