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How do I hardwire a 7 port USB hub into my truck for charging USB devices?

Discussion in 'The Coffee Shop ~ Chit Chat' started by PantheraUncia, Sep 1, 2012.

  1. PantheraUncia

    PantheraUncia New Member

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    I am sure allot of people want USB Chargers in their older cars, trucks, etc that do not have them. I have used a number of cigarette lighter adapters with either 1 or 2 USB ports and they are absolute junk. The most common point of failure is the cigarette lighter adapter and socket in the vehicle.

    So to get a real 7 port USB hub working in your vehicle it comes down to getting the right amps and voltage more or less.

    I looked at the D Link 7 port USB 2.0 HUB I have on my computer at home and the power adapter's specs are:


    • Input: 100-120V~0.4A, 50-60Hz LF
    • Output: +5.0V ===== 3A

    I looked around and some of the new USB chargers that plug into the cigarette lighter with 2 ports say they pull 3.1 amps (One USB port takes 2.1A and the other 1.1A) Apparently Ipads and tablets need 2.1 amps or they will not charge. (I noticed this with some USB ports on my laptop. The Ipad will "conntect" for data, but it will not charge off that USB port on the laptop which is odd.

    So my guess (I will need help here) is that if I want this 7 Port USB 2.0 HUB hardwired in my truck somewhere I would have:


    • Input: 9v-14v (Typically 12v)
    • Output: I need 2.1amps per USB port to charge what ever is plugged in so (14.7 amps) total and +5volts

    Also to make this work, I would need to regulate the Input down to 5v some how from 12v. In searching for the answer to all this, I also read that I might need a DC to DC converter? not sure how that works, it seems redundant.
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  2. Conlan Rose

    Conlan Rose Super Moderator

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    That's what stinks with DC it is difficult to change the voltage. But regulating the amps should be easier. This is probably why the usb chargers for the cigarette port die or kill the port but surprisingly the cheap one I got a while back has survive for like 3-4 years.
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  3. SurrealOne

    SurrealOne Former Member

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    You hardwire an inverter to do the AC->DC conversion ... and size that inverter based on the wattage you need and the type of equipment you'll be using (modified sine for things like coffee pots and saws ... and pure sine for TV's, computers, and the like).
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  4. moogvo

    moogvo Moderator

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    There are several ways to convert 12 volts into 5 volts. You can use a transformer, resistors, converters, regulators... Etc. Buying an inverter to convert 12 volts into 120 volts so you can reduce it back down to 5 volts is really incredibly inefficient.

    If nothing else, you can get one of those triple lighter plug outlets that have a USB connection and steal the regulator from that.

    The bad news is that you won't get a USB hub to handle 14 amps. 2 to 3 is about all you are going to get out of it.

    A dc to dc converter allows you to put 9 to 16 volts in and will give you a steady output voltage. In communications installations, we use dc to dc converters to operate 2 way radios off of a deep cycle battery as a backup. We set the output to 13.8 volts so that no matter what the battery voltage actually is, the converter provides a steady 13.8 volts until the battery is depleted.

    Similarly, I have an electronic cigarette that has a single 3.7 volt battery, but will let me adjust the voltage to the atomizer coils from 3.3 to 6.0 volts, regardless of the battery's charge and voltage.
    Last edited: Sep 1, 2012
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  5. SurrealOne

    SurrealOne Former Member

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    It's INCREDIBLY EFFICIENT when you buy a 400w inverter for 5 dollars at an auction. And these things show up at NC auctions all the time...
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  6. moogvo

    moogvo Moderator

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    An inverter converts amps into volts to make higher voltages. In this case, he is wanting to reduce voltage. The problem with converting 12 to 120 and back down to 5 is that amperage is drawn to create the high voltage and to run the modified sine wave at all times, whether the inverter is loaded or not. What you are doing is like going from north Carolina to Virginia by way of texas. If he has other use for 120 volts in his truck, then an inverter is okay for that, but I wouldn't use an inverter to do the job of a simple regulator or converter. It's almost like replacing the dome lamp with a household light bulb.
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  7. SurrealOne

    SurrealOne Former Member

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    Knowing Nak, I don't think he cares how it's done as long as it's cheap, effective, and reliable. An inverter can meet all of those criteria....
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  8. moogvo

    moogvo Moderator

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    Converters are cheaper than inverters and won't run the battery down if left on overnight. Just pointing out the options and the "correct" way to do it from an engineering standpoint.

    If GM were to make built in USB charging ports, they wouldn't do it with an inverter. There is always the triple dc outlet with the single USB port, then plug double USB port chargers into the 3 outlets. There's your 7 ports.
    Last edited: Sep 1, 2012
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  9. PantheraUncia

    PantheraUncia New Member

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    This is getting funny now :). What exactly is cheap? :) Could I potentially get 7 x 2.1A USB cigarette lighter chargers; gut them out so I have the reguators, pcb's, etc and then fabricate an enclosure that would fit all of them with one main postive in and negative out for the whole set of them.

    I assume they would need to be wired in parallel? wired in series the amps would go up; well, but they have the regulators on each one.....

    Anyway, let me know if that is one option, probably more expensive than it needs to be; and that would let my bypass the cigarette lighter socket.

    Come to think about it, my truck has 3 cigarette lighter sockets all in a row and I don't smoke, so I am already wired for 3 positives and 3 negatives right up to the dash if I remove all of them and hard wire USB ports up there behind the little flip door that hides them.
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  10. PantheraUncia

    PantheraUncia New Member

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    And I do have a 1500w power inverter, but I hate using it, and I was not considering using it to power a usb hub with 120v AC. It is for stuff that requires more power than a USB Hub....
    #10
  11. tbplus10

    tbplus10 Moderator

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    GM does make built in USB charging ports, it might be worth a look to see how their doing theirs and if it's a simple swap/install or entails lots of extra wiring and components.
    Many 2011 and up trucks come with the USB port that connects to the stereo and can recharge items.
    #11
  12. PantheraUncia

    PantheraUncia New Member

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    My Kenwood headunit has a USB port on it, but I believe it only has enough power for the 1 USB port, not sure it has power for charging an Ipad, it might charge a cell phone.

    I need multiple ports anyway (at least 3) for my personal phone, my on call phone for work, and my ipad. It would be allot simpler to reverse engineer a 7 port hub to get extra ports and make it compatible with the power system in the truck, well I thought it would be.

    And then if I have my phone plugged into the USB port on the head unit, where does the thumb drive go with my music on it ? :)
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  13. Jaele

    Jaele New Member

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    Just a quick note... Even though the iPad says its not charging it actually is, it's just not as fast. If you are plugged into the laptop and using the iPad it will recharge the battery a little slower then what is being used. Not sure if this helps you in your decision making.
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  14. moogvo

    moogvo Moderator

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    Originally, your question was how to take 12 volts and make it into 5. The easiest way, assuming that you do not have the electronics knowledge needed to design and build this particular circuit. Rather than to give you a parts list of the materials you would need to build it yourself, I told you that what you want is already out there.

    Advance auto sells a cigarette lighter adapter that has 3 lighter sockets and a USB port for charging. Now, you could get one of those and use it in one of two ways:

    1. Take the unit apart and take the already engineered regulator out and use that to power the USB hub that you said you wanted to use in the first place or,

    2. Use the unit as-is and buy 3 cigarette lighter to double USB adapters, plugging one into each of the unit's cigarette lighter sockets, giving you a total of 7 USB charging ports.

    At no point did I ever suggest you buy all of those items and dismantle them all for the parts to make a completely custom enclosure.

    Either way, you are never going to be able to pull 14 amps through any circuit of this type.
    Last edited: Sep 2, 2012
    #14
  15. PantheraUncia

    PantheraUncia New Member

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    Thats not what I meant..... Anything that gets plugged into the cigarette lighter socket is a problem, whether it is a usb adapter, spot light, etc. They are just really prone to failure.

    So my thinking was to get 7 x 2.1 amp cigarette lighter USB adapters where each one has the resistors, regulator, pcb and gut them and make 1 unit with a single hot and a single cold lead that I can wire into the truck somewhere making it a clean install or factory type look.

    That should give me 7 usb ports with 2.1a to each one for faster charging.
    #15
  16. PantheraUncia

    PantheraUncia New Member

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    That is good to know, although I think I am using the power quicker than it can charge in that case :)
    #16
  17. PantheraUncia

    PantheraUncia New Member

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    I got a chance today to disassemble one of the 2.1a single USB cigarette lighter adapters and here is what I found:

    [​IMG]
    Here you can see the parts of the USB adapter.

    [​IMG]
    Top view

    [​IMG]
    Bottom View

    [​IMG]
    Close up of the hot and cold connectors.

    So this thing is already regulated down to v5 2.1a from 12v. What I am thinking about doing is taking 7 of these units and gutting them out of their cigarette lighter adapter and then installing them in a 7 port USB Hub housing for a normal USB Hub.

    I am going to remove the coil spring for the positive connector and replace it with a red 10g wire for hot and the clip (negative) with a black 10g wire for the negative on each one.

    I am thinking about adding a terminal strip for later expansion if needed.

    And then I can just take the positive and negative from the cigarette lighter socket in the truck, remove it and put caps on them to connect them to the terminal blocks wires.
    #17
  18. PantheraUncia

    PantheraUncia New Member

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    Actually I just found this:

    http://www.ladyada.net/make/mintyboost/icharge.html

    Apple is trying to be sneaky. They always have to do something dumb to make stuff not work with normal stuff.
    #18
  19. SurrealOne

    SurrealOne Former Member

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    That's why I don't monetarily reward them with my money. Ever.
    #19
  20. PantheraUncia

    PantheraUncia New Member

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    So this project is moving forward now after being benched for a few weeks. After learning how to solder and make a mess of it at [MENTION=50075]SurrealOne[/MENTION] 's place, I picked up a soldering iron and decided I was going to fix me some leads on the USB charger in the photos above.

    (This is my second attempt at soldering anything) so it is not the best.

    [​IMG]

    [​IMG]

    [​IMG]

    So what I have now is 1 2.1amp USB charger with leads that I can either splice into my + and - cigarette lighter power cables behind the dash. All I need are 6 more to get 7 ports and an enclosure that will fit it all.

    Then I will have my 7 port USB charging station in the truck.
    #20

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