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Getting USB power from car's fuse box

Discussion in 'General Electronics Discussion' started by AtomZap, Nov 29, 2016.

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  1. AtomZap

    AtomZap

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    Nov 29, 2016
    I'd like to have USB power in my car, even when the key is not in the ignition. I understand that I can get always-on power from my fusebox.

    I have a 5th-generation Honda Civic. The http://www.geocities.ws/ng_randolph/Civic/civic_info.html therefore applies to my car. Based on that pic, the "#1" (leftmost) connector is always on. So now I'm trying to find a way to link my USB cable to that.

    I already have a USB cigar-lighter car charger. What would I need to buy from the store?
     
  2. KTW

    KTW

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    Feb 22, 2015
    Last edited: Nov 30, 2016
  3. AtomZap

    AtomZap

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    Nov 29, 2016
    KTW, thanks for your reply. Could you kindly tell me whether I would need to create a hole to get the wiring from under the hood (where battery is) to the car's interior?
    Also, I think I have a spare connector (the always-on connector) in the fusebox. Why not use it?
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    You may have to. or you may be able to go through an existing wiring loom rubber grommet
     
  5. KTW

    KTW

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    Feb 22, 2015
    If that's the 50 amp fuse it's way too much for what you are adding to it.
    This requires a 10 gauge wire, too heavy for what you need.
     
  6. AtomZap

    AtomZap

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    Nov 29, 2016
    thank you, ktw and davenn for your replies.

    I've taken pics of the part below the dashboard, including fusebox. http://imgur.com/a/M38ue.
    Questions: Is this 12-volt fuse slot always on (on when the key is not in ignition)? If so, do I havea spare 12-volt fuse slot?


    There must be an existing wiring loom rubber grommet, right? I mean, there has to be a preexisting "tunnel" for all the other electrical stuff in the cabin, right? Or do I need to create a new hole?

    (How can I edit a post of mine? I wanna add this URL to my OP.)
     
    Last edited: Nov 30, 2016
  7. davenn

    davenn Moderator

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    yes, likely to be more than one existing place, it really just depends on how accessible they are under the dash area
     
  8. Kiwi

    Kiwi

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    Jan 28, 2013
    Just run a wire off the spare live #1 connector through a 2A fuse to a cig lighter socket. Put the fuse as close as possible to the fusebox.
    You will also need a negative earth wire secured directly to the car chassis.
     
  9. KTW

    KTW

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    Feb 22, 2015
    You can test all the 10 amp fuses in the picture with a 12 volt test light to see if there is 12 volts across both sides of the fuse when the key is off.
    If you find one then you can use a piggy back to replace that fuse,reinstall the 10 amp fuse in the piggy back and add a 2 amp fuse to your new wire to feed the charger.
    To answer your question, the best place to see where the wires are coming through the firewall is in the engine compartment.
     

    Attached Files:

    AtomZap likes this.
  10. AtomZap

    AtomZap

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    Nov 29, 2016
    My car has a cig lighter socket, and it is working just fine. But for security, I can't use that socket to power my device(s).
     
  11. davenn

    davenn Moderator

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    Sep 5, 2009
    what does that mean ??
     
  12. AtomZap

    AtomZap

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    Nov 29, 2016
    Sorry for my delay. To clarify: I don't want anyone to see that I have a device plugged in. And since the cigarette socket is in such a visible spot, I don't want to use it.
     
    davenn likes this.
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