[info] Weatherpack - How to Build a Wiring Harness

Hardware inside and outside of the ECU
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AndreyB
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Weatherpack - How to Build a Wiring Harness

Post by AndreyB »

This thread is here at least to save this picture for my own reference, well, also to share the source link: http://www.colorado.edu/physics/EducationIssues/podolefsky/electric_motorcycle_howto_wiring.html
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Re: Weatherpack - How to Build a Wiring Harness

Post by kb1gtt »

That instruction is yuck from my point of view. There are many bad practices shown there. Things like using low quality crimp tools, and not mentioning to use stuff like fluxoff to remove the excessive flux, is bad news. If you use a proper crimp process it's reasonable to expect a 10 year or more life out of the connection. If you use sub par crimp processes, it's commonly you have contact ohms which causes heat issues, that can include fire. Also the contact resistance can cause tank circuit issues. Tank circuits are known for causing over voltage situations, which typically result in fire. Then there are things like skewed signals and odd gremlins that you chase for hours as you debug a problem. It's a really good idea to put in the extra effort to make a good and proper electrical connection.

I once had a customer request the use of a dellcity crimped on connector. I had a heck of a time getting a crimp tool that would crimp that connector properly, but I eventually got one that passed the tug tests. During my efforts to get that crimped properly, I learned allot about the importance of a proper crimp. I spend a bunch of time with a thermal camera seeing how it would heat up. I also got to run things through simulated circuits that mimicked real world solenoids and motors. I got to see some really odd issues caused by the ohms of a poor connection. If you don't want to chase magical beasts, and gremlins, I highly recommend doing proper crimps.

Here's some videos that help show proper crimp tools, and proper crimp processes.
-- This is a TE basic crimp training video it's 5 minute long
-- This is a guy testing proper tool which pulls at 193 lbs video is 1 minute
-- This is that guy testing a common non ratchet hand tool, it pulls at 12 lbs video is 1 minute
-- This is again that guy testing the above, but got it to pull as much as 27 lbs video is 1 minute
-- This is that guy showing a 3rd party ratchet tool, this one pulls at 83 lbs video is 1 minute

See below video relative to crimp procedures and quality inspections.
-- TE training advanced video 20 min

The summary of these videos is that tug testing is a good way to determine a good crimp. The OEM ratchet crimp tool passes at about a 200lb tug test, while an after market ratchet tool failed at about 1/2 of the OEM test, and non ratchet tools fail at about 1/10 of the OEM test.
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Re: Weatherpack - How to Build a Wiring Harness

Post by AndreyB »

If I do not trust my cheap crimping tool would it make things better if I solder over the crimp afterwards?
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Re: Weatherpack - How to Build a Wiring Harness

Post by kb1gtt »

At least for a while, and assuming your cheap crimp tool doesn't damage the connector, which is common on these more sensitive connectors like the weather heads, but less of an issue on flat spade, or ring terminals. Keep in mind your solder has flux, and you'll end up with extra flux on the wires. The flux is very aggressive when hot, and less aggressive when cold. Even when cold it still tends to corrode connections which causes damage, not today, but it is common to have a problem in 1 year-ish. I would say a proper crimp is among the best connections you'll get.

If you have patience and a good scrub brush, soldered with flux removed can be reasonably good as well. Many flux chemicals can be removed with isopropyl alcohol (rubbing alcohol).
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Re: Weatherpack - How to Build a Wiring Harness

Post by Horizenjob »

Proper crimping, soldering and wire wrapping provide gas tight connections. That way there will never be oxide between connecting parts. One reason you get such weird results with poor crimps is that metal oxides function like diodes. They will look OK if you use an Ohm meter one direction, but not the other! You can look at things like old battery chargers and see they use the metal case as a diode with a metal plate and oxide in the middle. This makes a crappy diode but it works and sure would have been cheaper before semi conductor diodes.

One reason I hate connectors is the expensive crimping tools. At my last job we had an whole tool box of them at several hundred dollars apiece. Like a dozen, so just finding the one you needed was exasperating, not to mention you had to look up the serial numbers.
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Re: Weatherpack - How to Build a Wiring Harness

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At work I got annoyed about finding the proper tools. I'm only on the floor once every month or so, but still it annoyed me. So I made cards like the attached and placed them in the bins where the components reside. I like t his approach as the picture of what should be in the bin, helps when people put the wrong thing in the bin, as well when there is an extraction tool, I put that there as well. I find this very helpful.

About tin coated and gold coated connectors, I seem to recall they don't oxide, instead the nickel in the tin tends to crystallize, which is based more on heat and scratches in the surface finish. It looks allot like oxide, but is a bit different. You can often get a much better long term connection if you put a dab of grease on the connector when inserting it. This prevents the surface scratched, which can be both a good and a bad thing. If you have some dust left from shipping or MFG, it might not scrape off, but typically these are good and reasonably clean, so that's typically not a problem.

Also do NOT use silicone based greases, silicone is a dielectric and it does some really odd things if you try using that in an electrical connector.

Lots of good info in the "tin commandments" see PDF found here http://www.te.com/documentation/whitepapers/pdf/sncomrep.pdf

Also good is the "golden rules" found here. http://www.te.com/documentation/whitepapers/pdf/aurulrep.pdf
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