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USB Charger for all things USB

Crispin Feb 25, 2010

  1. Crispin

    Crispin Administrator Staff Member Guru I am in great_britain

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    Well, my first DIY project. Small yet pretty handy if I may say so
    I have a sat nav and phone which both charge of a mini USB. Each though has a stonking great plug for the cig lighter and cables running across the dash.

    I was looking at one of the (many!) blank plates I have in the lowly LC4 (Like I said on another thread - one day I want a car that has no empty holes. All full of toys) and though I could cram two USB plugs into it.
    Each of the devices only uses 5V. USB is rated at 500ma max but these devices can edge over it when charging.

    So, armed with two USB sockets and a 7805 voltage regulator from Maplin for a princely sum of £1.50 I set about carving up one of the blanking plates.

    Here are some pics:

    The untouched plate. Mr T made sure it's strong enough for something:
    DSCF0036.jpg

    A view of the inside carved out:
    DSCF0038.jpg

    A note on the above (You figure these things out once it's too late!) Leave the middle set up upright "fins" in place. I hacked the inner portion of them off. You can see the short piece sticking up. Leave more of this sticking up. It makes a nice cage for the reg and heatsink.

    Top view of the hole carved out for the usb plug. Make sure you carve the hole close to the upright support. This way you can glue the whole plug to the fin which should give a nice strong bond. Failing that the plug will be suspended in the case. Not strong. Use a 5.5mm drill to drill out three adjacent holes. Square them off with a dremel (I wish) or a scalpel.
    DSCF0040.jpg

    The voltage regulator in it's heatsink. The heatsink, by shear luck, is the perfect size. The wide part of the fin is exactly (well, 0.2mm wider) than the blanking plate. As it's ali, a few rubs with sandpaper would sort it out.
    DSCF0041.jpg

    The USB plug in place: (I've since straightened it up a bit and unbent it)
    DSCF0042.jpg
    The heatsink, voltage reg and usb #1 in place.
    DSCF0045.jpg


    Tomorrow I'll to the other one and wire it all up. Once it's working and tested I will drown it all in potting compound which, once set, is permanent. It is good up to 130c and does a far job at heat transfer (not that there will be a lot of it)
    The voltage regulator is rated at 1A with it's own current limiter and thermal cut off so for car use it is pretty safe in the small area behind the dash. That said, there will still be a 2A QB fuse before it for shorts etc.

    Not sure where I will pick up 12V though. I'm sure I'll find something behind the dash. Worst case would be cig lighter.


    ...and she's done.

    In between showers today I decided to finish it.

    I installed the sockets under the mirror switch, I might move them to the LHS where the 2nd Start switch should be.
    Anyway, here are some pics as well as "how to" dismantle the center console.

    Please ignore the crumbs. That was this morning's toast
    Thanks to Gary's post on how to start removing the trim.
    First unscrew the gear knobs. (I may swap them when I put them back on to thwart stupid thieves. "This car has two gears but 6 High/Low range settings!")
    DSCF0047.jpg


    DSCF0062.jpg

    Some tugging at the console will cause the front clips to come undone.

    DSCF0063.jpg

    Remove the rubber mat in the drinks holder (non 120 drivers may skip this step. I believe they have no fancy stuff like drink holders )
    I did not see this initially and ended up pulling the whole lot off, including the front of the bin. Was pretty difficult to remove the the handbrake and gear levers.
    Once screw are out it will just pull up, slide forward slightly to get it over the handbrake.
    DSCF0066.jpg

    Once off, this little felle is visible. It's mention of VSC suggest it's for the stability control? Wonder what it is. Will look through the workshop manual at some point. I suspect it could be a yaw / attitude sensor? Nice and central to the vehicle.
    DSCF0064.jpg

    Some firm tugging will remove the console with the cig lighter, heater switches etc.
    DSCF0065.jpg

    Life is made easier if you remove all the plugs. No need to remember what's what. They all taped together as well as each plug being different. Even the L/R seat heaters.
    DSCF0067.jpg

    Route the wires through the fuse area. The fuse for the USB power is in here as well. It's an inline fuse and just lies at the bottom of the fuses.
    DSCF0069.jpg

    Once cable is routed through, I stripped some insulation of the pink wire which was positive. Covered everything up again with good quality insulation tape. Not the supermarket rubbish that unwinds itself after 6 months. I could have used some of those splicer clips but had none and did not fancy a trip to Halfords.
    DSCF0070.jpg

    Earth was picked up on the RHS. The panel around the fuses cover is held on by clips and one screw. This screw screws into a piece of nice shiny metal spot welded to the chassis.
    DSCF0072.jpg

    The final product:
    DSCF0068.jpg

    While I was there, I thought I would pick up some slack on the handbrake cable. When applied, you could pull it almost vertical. It would start biting about half way but had a lot of travel in it. If pulled fast you could also hear the cable slap the underside of the chassis. Mr T did service this and though it to be ok.... I know not. It did lock the back wheels through when fully one and try to drive.
    Anyway, I adjusted the nut a good few turns and now all seems well. It is fully applied in half the "distance" it used to be, the slap is gone and most importantly, there does not seem to be any noticeable drag on the car. First 5-10 turns could be done with my fingers.
    Note: Someone please tell me if I have done good or done bad on this. Should I put it back to where it was and adjust it elsewhere.

    DSCF0073.jpg

    Back to the USB:
    It works but it does not.
    Oddly enough it works with the phone and when directly connected to sat nav it's fine. Charges and is happy. However, when I connect it to the sat nav cradle it does not charge. I can only assume the power cable for the satnav is not actually 5V and might be a bit higher. I will strip it down and see what's going on.


    Next project: Turn the centre bin into a fridge with a couple spare Peltiers I have lying around. Should be perfect for keeping my beer, urm, mineral water chilled on those long trips.
     
  2. TonyP

    TonyP Super Moderator Supporter I am in uk

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    It might be worth adding some capacitors to that circuit to smooth out any noise etc.

    See here for an example: epanorama
     
  3. Crispin

    Crispin Administrator Staff Member Guru I am in great_britain

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    Yup, so far it has "sort" or worked. It appears most devices do not like the +/- data pins (the inner two) to float and must be pulled low. With open data pins, most devices do not recognise the plugs and don't charge. I did not know this at the time and now have to redo the whole thing.
    Seeing as I have the carputer in there, I am making another PSU (tapped off the 'puter) which I will use to power these, as well as just connect them to the 'puter.
     
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