# Adding permanent USB ports (lots of pictures)



## horseoutside (May 29, 2013)

Just finished adding two permanently powered USB ports for charging phone/tablet/GPS navigation.










Main points:
* Mounted in the blank button between fuel cap release and boot release buttons. (I don't have the internal movement alarm disabling button, so this was blank.)
* Powered permanently from the 15A cigarette lighter circuit.
* Independently fused.
* When idle, it draws 17mA at 12V. (0.204W)
* Capable of supplying up to 3A at 5V.
* Looks like a high-current supply to a phone/tablet. (Like an AC adapter)
* No cutting/tapping of original wiring.

The bad:
* It's not quite as tidy as I was hoping for. 
* The idle power consumption is slightly higher than I was aiming for. ([email protected] actual vs <[email protected] intended)

The unfinished:
* I haven't added red LEDs underneath it yet to match the dashboard lighting.

So, here's what I did:









Removed the button assembly by pulling gently on the left and right sides to release the clips. It's pretty weak, it comes away easily. Removing the button blank was a bit of a pain, you need to get a screwdriver/something pointy in from the back, between the buttons, to push the clips on the left and right sides out of the way.









Used a rotary tool with a milling bit to mill out all the plastic supports and walls.









Testing fit of USB ports, button blank is nearby.









Preparing to make a big hole for the USB ports.









First bit of cutting that will be visually apparent. No going back now!









Fine fitting done with small hand files.









USB ports anchored to the inside of the button blank by bending some of the little arms backwards. Not sure if the thin arms at the sides are intended for port mounting or plug friction, but I don't need them for plug friction as plugs are more than secure enough.









Using 220Ω resistors to tie the USB data lines together, which will indicate to most devices (not Apple devices though) that it's a high current source for charging. Apparently the Chinese standard is to just bridge them, the EU standard is to use a 220Ω resistor, and Apple do their own damn thing with more resistors as a voltage divider to produce varying voltages on the two data lines, which indicate various types of chargers. I don't own any iDevices, so I opted not to consider Apple compatibility.









Tidying it up with heatshrink.









Test fitting. Oops, it wobbles around.

















Pulling some donor plastic from stuff in the parts box.









This turned out to be much too thick, so I thinned it with more milling and filing.









Cutting up the waste material around a sheet of LRFs (Little Rubber Feet ) to use as flexible spacing material and vibration dampening material. Never thought I'd use the waste material from this, I owe this idea to the better half.









Gluing rubber pieces to the thinned piece of plastic.









Here's the switching DC-DC power supply, a Hobby King UBEC 3A/5V from http://www.hobbyking.com/hobbyking/stor ... 3a_5v.html which takes 6V-23V and provides a stable 5V. If it's happy all the way down to 6V it ought to survive engine cranking without charging devices noticing but I haven't tested that yet. Useful for other projects I have planned...









Whole assembly going into the button housing. It fits with a click and doesn't move. I've had to weaken the spring arms inside the USB port to hold plugs less securely, as the clips on the side of the button aren't designed to hold against someone yanking out a USB connector. This will likely be the first thing to fail, I'll probably need to figure out another way of spreading that strain. For now, I will unplug gently.









Making a wiring harness to allow me to plug into the existing cigarette lighter plug (Audi part # 191 919 321 if anyone is curious!) and adds an inline blade fuse holder.









Removing the tray and lid assembly is easy once you know how. There are three clips (looks like one was already broken on mine...) and I found it easiest to use my fingertips to push these from the inside by sticking my hand into the slot for the button assembly. I used a plastic spudger to release them the first time because I didn't know where the clips were.









Another shot of those clips, just in case someone finds it useful.









The harness wiring is routed under the tray where there's plenty of space. My stereo AUX/USB cables are also stored under there for now, I'll be adding those ports inside the tray later, I think. The coroplast-wrapped wiring loom on the left is for the fuel cap/boot release buttons/lighting.









The tray/lid assembly snaps back in easily, the buttons snap onto that, and we're all done.

Thanks for reading!

How could I have done this better? Where do you put your USB ports? Suggestions welcome!


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## Hoggy (May 8, 2002)

Hi, Looks good & very neat. Better than plugging the USB adaptor into ciggy lighter socket.
Can't understand why it would draw a current when idle though.
Hoggy.


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## horseoutside (May 29, 2013)

Hoggy said:


> Hi, Looks good & very neat. Better than plugging the USB adaptor into ciggy lighter socket.
> Can't understand why it would draw a current when idle though.
> Hoggy.


Thanks!

Ah, there's always some overhead in power conversion. Better than a transformer anyway! Might see about getting it switched, but I think it's low enough that I don't need to care. If I'm concerned I have a little Samlex "battery guard" unit (http://www.samlex.com/site/products/pro ... el=BG%2010) that will cut off the power when the voltage drops below some level you choose.


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## Charlesuk (Mar 12, 2012)

That's a really good idea, and it's still rather tidy! Good job 

Sent from the mobile device


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## Mondo (Feb 20, 2009)

Very nice, bud. Looks damn tidy to me; dunno what you mean about not being tidy enough. 

[smiley=thumbsup.gif]


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## IC_HOTT (May 29, 2010)

Excellent mod, I think it's very neat and good pics and write up.

Can you add some detail about the connections please? :wink:


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## horseoutside (May 29, 2013)

Thanks for the comments everyone! I don't think it's very neat, but I saw and obsessed over all the little mistakes, slips (milling bit, files, screwdrivers, glue...) so I have a slightly different perspective on it! I saw how the sausage was made. :/

I'm mostly worried about the connector assembly coming out when unplugging something, it has happened several times in testing and I haven't decided on how I'm going to take that (relatively serious) strain off the weedy button clips. Trying really hard to avoid gluing the whole damn thing in!



grasmere said:


> Excellent mod, I think it's very neat and good pics and write up.
> 
> Can you add some detail about the connections please? :wink:


Happy to. In order:

Using two spade crimp connectors to get into Audi's original cigarette lighter plug (#191 919 321) without having to cut it up or mutilate a whole cigarette lighter assembly. They fit, but not securely enough, so I have some heatshrink and a twist tie holding those connectors firmly against the plug. One of the shonkier parts of the whole thing, but I'll need to revisit this later anyway for the 12V power port relocation project...

From there it goes to lucar spade connectors for the inline fuse, then a little red JST plug. I'm using this because I have a pile of these for other projects and LED lighting around the house. I've sort of standardised on these connectors for 12V work everywhere including in a previous car, so it made sense to reuse it here.

The little white connectors between the DC-DC converter and the USB ports is another type of JST plug, used only because I want to be absolutely sure I'll never mix up the 12V and 5V supplies. I will likely be pulling 5V off this side of the system for another little project later, and I've blown up enough parts in the past to teach me to be careful with this. 

Er, sorry, I accidentally an essay. Does that answer your connector question?


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## IC_HOTT (May 29, 2010)

horseoutside said:


> Er, sorry, I accidentally an essay. Does that answer your connector question?


 :wink: yes thanks, appreciated


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## GPT TT (Mar 18, 2012)

Very good job


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## g-unit (Jan 21, 2012)

Top notch!


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## silkman (Jul 29, 2004)

**thread resurrection alert**
Very nicely done.

Do you remember where you got the dual usb socket? Cant find something similar...


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## Exuptoy (Sep 12, 2017)

silkman said:


> **thread resurrection alert**
> Very nicely done.
> 
> Do you remember where you got the dual usb socket? Cant find something similar...


I added these to a spare tile on the dash of the T5 last year. I just cut off the panel mounting tangs and set them in with a hot glue gun.

http://www.ebay.co.uk/itm/1x-Dual-Doubl ... Jh8r2zhjlQ


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