Today's Message Index:
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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
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| Subject: | Re: 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 <lyleap@centurylink.net> 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
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| Subject: | Re: Soldered lap splice has more resistance? |
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
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| Subject: | Re: Soldered lap splice has more resistance? |
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
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| Subject: | 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.
Bob . . .
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