charging iPhones with 12v battery

Discussion in 'General Electronics Chat' started by electronewb, Apr 17, 2013.

  1. electronewb

    Thread Starter Member

    Apr 24, 2012
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    What's the best way to to charge an iphone from a 12v battery. Using an power inverter so going from DC to AC back to DC? or using a 5v voltage regulator?
     
    Last edited: Apr 17, 2013
  2. poopscoop

    Member

    Dec 12, 2012
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    A car charger. USB charging can be funny, as the phone may need to "request power".
     
  3. electronewb

    Thread Starter Member

    Apr 24, 2012
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    Not sure I know what you mean!!!!
     
  4. poopscoop

    Member

    Dec 12, 2012
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  5. electronewb

    Thread Starter Member

    Apr 24, 2012
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  6. TheComet

    Member

    Mar 11, 2013
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    The Iphone won't charge itself when plugged in to a USB port unless the hosting device tells the Iphone it's allowed to.

    I once read somewhere that you can bypass this if you apply 3.3V on each signal line using two resistors (don't connect the lines together).

    TheComet
     
  7. t06afre

    AAC Fanatic!

    May 11, 2009
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    If you can afford an Iphone. I am sure you can afford about 10 dollar on a car charger to. Unless you know how to do it. You may end up with a non working phone ;)
     
    screen1988 likes this.
  8. electronewb

    Thread Starter Member

    Apr 24, 2012
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    It has nothing to do with a car it's to charge it for when I go on remote locations I got both the battery and the inverter for free so might as well use them for something. http://www.youtube.com/watch?v=VBAY_j_4CJc My question is is it more efficient to just build one of those Altoids charger or use the inverter?
     
  9. Gibson486

    Member

    Jul 20, 2012
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    Well...you are in DC...so no need to convert to AC only to go back to DC. You are wasting most of your energy right there. They have battery charger circuits that do what you want to do.
     
    Mitch conrad likes this.
  10. electronewb

    Thread Starter Member

    Apr 24, 2012
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    Thanks. Tthats what I was thinking. I wonder how much energy in percentage I'm losing with the inverter. More or less than 50 percent?
     
  11. electronewb

    Thread Starter Member

    Apr 24, 2012
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    So I ended up using a cigarette lighter to USB adapter I rewired the + and - works like a charm Now I was wondering if I could push it and charge a laptop this time? Somehow bypassing the AC power supply going straight DC to DC
     
  12. vk6zgo

    Active Member

    Jul 21, 2012
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    The "car charger" plugs into the "cigarette lighter"(or what used to be called that) socket in your car,& converts 12V DC to the required charging voltage for your iPhone.
    It doesn't care where it gets its 12V DC from,so you could buy the required socket,complete with wander leads,connect it to your battery,
    plug in the "car charger" & be good to go!
     
  13. electronewb

    Thread Starter Member

    Apr 24, 2012
    260
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    But I'd like to charge a laptop and I red that laptops are a bit more finicky regarding voltage
     
  14. t06afre

    AAC Fanatic!

    May 11, 2009
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    Modern laptops, will not in any way charge. Unless they are connected to an approved powersupply. The charger will communicate with the laptop. If the laptop receive no data or wrong kind of data. It will not charge. And in some cases not start at all. You will have to get a combo power supply. That can handle both 12 volt and mains. You can order this at the place you got your laptop
     
  15. tigershark

    New Member

    Apr 23, 2013
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    I have been successful doing this same thing by simply using a 5 volt regulator. It may be interesting to note that if one happens to have a "spare" usb charger and is willing to sacrifice the micro B or one of the end adapters, it is only necessary to connect wires 1 and 4 to the positive and negative contacts on the phone or battery and simply plug the othe end into a computer or some 5 volt dock for an unspecified period of time to achieve a full charge. In this case neither an inverter or regulator is required. However if you so desire to use the 12 volt battery a voltage regulator of not less than 5 volts is a must. No "fast charge" from higher voltages here! I learned this the hard way when my charger malfunctioned and in order to charge the battery cell I used the stripped down USB cable quite successfully until payday allowed the purchase of proper gear. No ill-effects were observed and I later resoldered the USB cord and restored it to normal. Let me know how it goes. note: if you have a multimeter handy you may monitor the rechatging processs in real time in order to not exceed the cells reccommended milliamp spec. Tigershark
     
  16. electronewb

    Thread Starter Member

    Apr 24, 2012
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    For some reasons I can't start a new thread I tried on 3 different computers All I get is a blank page after I submit my new thread
     
  17. electronewb

    Thread Starter Member

    Apr 24, 2012
    260
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    Ignore previous post
     
  18. TheComet

    Member

    Mar 11, 2013
    88
    12
    From 12V down to 5V? I suggest using a step-down converter for that. It's going to be a lot more efficient than simply frying the 7V over a linear regulator.

    http://www.linear.com/product/LT1375
     
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