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I'm planning on building a device for my car that sits somewhere in the rain tray or behind the dashboard. It will use automotive connectors so that things are sealed, easily connected and disconnected, etc. I plan on having it be controllable/configurable over USB, but I still want the unit to be sealed.

How feasible would it be to run the USB connection through the normal pins of the sealed connectors? It would be regular stranded conductors in the 18-20ga range, and I'd probably have to bundle, twist, shield and heat shrink them myself.

Is this a reasonable approach or is there something better I should be looking at... some specialized USB connector or something?

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  • \$\begingroup\$ I've seen pictures of specialized USB connectors protected from environment in another answer. I think that they may even have been for automotive use. I'll see if I can dig them up. Anyway, keep in mind that whatever you do power pin must mate first! \$\endgroup\$ – AndrejaKo Sep 11 '12 at 23:24
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    \$\begingroup\$ Here's a related question. \$\endgroup\$ – AndrejaKo Sep 11 '12 at 23:32
  • \$\begingroup\$ @TobyLawrence More likely than not, your approach will work. Perhaps, the data rate over USB will be lower. It might help if you make the cable with automotive connectors and evaluate it before you commit to the design. \$\endgroup\$ – Nick Alexeev Sep 12 '12 at 0:13
  • \$\begingroup\$ Yeah, I'd be connecting to a regular USB plug suitable for insertion into a host computer... it would just be everything before that that is custom. \$\endgroup\$ – Toby Lawrence Sep 12 '12 at 0:53
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I would recommend using proper sealed usb connectors. Molex makes some. They will be much more reliable than making your own. If you don't like the molex ones, searching for "IP67 usb" brings up several alternatives.

enter image description here

http://www.molex.com/molex/products/family?key=industrial_usb_type_a_and_b_plugs_and_receptacles&channel=products&chanName=family&pageTitle=Introduction&parentKey=sealed_connectors#overview

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  • \$\begingroup\$ Those Molex ones are mighty expensive! I heeded your advice and decided to do a bit of searching myself. I found a lot of options, but Mini USB seems to be where the sweet spot is... the receptacle ends up being 12 - 13mm in diameter which I potentially have the enclosure face real estate for. The normal USB connectors are hugeeee for sealed versions. \$\endgroup\$ – Toby Lawrence Sep 12 '12 at 0:42
  • \$\begingroup\$ Link to the ones I found for Mini USB: conec.com/catalogs/c1/ioconnector/… \$\endgroup\$ – Toby Lawrence Sep 12 '12 at 0:42
  • \$\begingroup\$ Yep, there is a wide variety depending on your needs. Molex just happened to be one I've seen before. \$\endgroup\$ – Grant Sep 12 '12 at 0:49
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In general, I have not had problems running USB (including high speed) through all kinds of nonstandard connectors, particularly multipin military-style circular connectors.

It seems to be much more important to use genuine USB cable between the connectors. Don't try to create your own cable from discrete wires and shields, etc.

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  • \$\begingroup\$ Well, it wouldn't be possible to do that as the contacts only come in one wire gauge range (16-20ga) that isn't small enough to crimp typical conductors in a genuine USB cable. In this case, I'd have to build my own cable, essentially, and do the twisting, etc. \$\endgroup\$ – Toby Lawrence Sep 12 '12 at 2:21
  • \$\begingroup\$ @TobyLawrence - Just because the connectors specify a maximum gauge doesn't mean you can't use them for smaller gauge wires, it just means that they may not crimp reliably onto those smaller gauge wires. If you're willing to do the crimps by hand, and possibly solder them in addition to crimping them, it should be no trouble at all to make them work, and the connections should be plenty relible. \$\endgroup\$ – Connor Wolf Sep 12 '12 at 2:41
  • \$\begingroup\$ While it's generally impossible to put larger gauge wire into smaller gauge crimp-pins, going the other way (small gauge wire in large-gauge pins) is generally not too much trouble. You may have to solder the pins after crimping them, to get them so stay attached reliably. \$\endgroup\$ – Connor Wolf Sep 12 '12 at 2:43
  • \$\begingroup\$ And there's certainly no reason you can't put extra copper (a short piece of the proper-gauge wire) along with the USB wire into the crimp region of the contact so that it works as intended. \$\endgroup\$ – Dave Tweed Sep 12 '12 at 3:24

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