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  1.'s Avatar
    ...Hi guys sorry if this's not the correct place for posting this thread!

    I have an iPhone 3GS - 32MB

    *****For those who want to ONLY Know wich is the doubt that I have go to the last paragraph!
    *****If you want to know what was the project I've done, wich is nothing new, lose the 5 minutes reading it and do it yourselfs too! :)

    ******CHARGER VOLTAGES TO E PRESENT IN USB Data+ and Data- for charging the iPhone:

    Everyone knows that the "iDevices" charger for being acepted and efectevly charge the Device as to have present in the Data- and Data+ of the "USB conector" certain voltages so that the iDevice recognizes the "certified apple charger"....

    ALSO depending on wich voltages it identifies if it is a normal charging conected to the USB port on your computer wich drains 0,5A (500mA) from the computer's USB port and if at Data- we have 2,8V and at Data+ 2,0V te charger it's recognized as an EXTERNAL CHARGER and it will drain about 1A (1000mA) from the charger! - this distition it's obvious for those who haven't followed what I meant, that not all USB ports can supply 1A wich would damage the computer's power supply otherwise of course we would use allways 1A and the charging with allwys be a lot faster (theoretically, not in praticce, half the time for a full charge)!


    At the moment I've just finished an "external" battery for my phone! - i.e. I've used a laptop battery that is going to be VERY usefull when I'm travelling that has 10 times the capacity of my iPhone's 3GS battery... In pratice I will use this battery for charging or allways conected, if I'm seated with my backpack in a long train travell, to my phone when I don't have a wall socket or a computer at hand... this is done with 98% efecience using a DC to DC converter based on the "34063AP" IC... Datasheet search: 34063AP ..... wich makes the laptop battery be an extra, very practicall since I've managed to insert everything inside the battery, power supply!!!


    The cirtuit is working perfectlly as I projected it and indeed I've noticed that the eficiency is really almost 100%... (this means that in pratice there's almost no loss in charging the battery in a socket and the using the battery to charge my iphone making this a very usefull method of having the iDevice working for 10 times (in the case of my battery) longer without needing a power socket or a computer for charging the iPhone!


    since it's an "hardware stuff" it' not because it's jailbreaked or anything like that!
    I've noticed along doing this project that all the carefull resistor calculation I've done so that I would put the refered voltages in USB Data+ and Data- so that the iPhone in charging mode would drain 1A (1000mA) fro the battery for fast charging.... BUT when I was introducing a little switch for the regular 500mA for when I just want the external batery to serve as a power supply in wich thje iphone is not charging is simply using the external batery's energy insteard of is internal battery... (like if I was using the iPhone allways conected to the USB port on my computer..and this way when the "train travell" finishes I disconect it and I've been for the past day using the phone and when I'm ready to leave the train (or plane or ship) the iPhone is fully charged because he never used the internal battery) I'VE NOTICED THIS:

    *******THE DOUBT:

    FOR SOME REASON WHEN I SIMPLY CONNECT THE CABLE TO MY PHONE 3GS WITHOUT HAVING CONECTED NO VOLTAGES TO Data+ nor Data- the phone charges with 500mA as if there was present in Data+ Data- the mencioned 2.0Volts , BUT They're not even conected!

    I've tried conecting the cable this way (with Data+ and Data- not even conected) to serveral devices that have USB plug (set top boxes, computers, laptops, routers) and MY iPhone 3GS charges with them all!....
    I EVEN TRIED A DIRECT CONECTION using a stabilized power supply using regulator IC 7805... and it charges with 500mA.....

    SO, I NEVER GET THE MESSAGE: "Charging is not supported for this device" - wich bugs everybody's minds so often!!!

    **** MY QUESTION:

    - Is this ONLY a property of the iPhone 3GS?
    - Is this a property of ONLY "MY" iPhone 3GS?


    Thanks guys!...
    IF YOU MAY FIND USEFULL TO DO THIS EXTERNAL BATTERY PROJECT JUST SAY SO THAT I'LL HELP YOU OUT!!! using a broken laptop's battery that is working but you have no use for it JUST SAY SO and I can help you guys out ding your project... (it's diffferente for each battery since the main problem is "where to get the energy from the power cells since it varies from battery to battery AND THE CHARGER SINCE THE LAPTOP IS BROKEN HAS TO BE DONE CAREFULLY BECAUSE Li Ion Batteries MUST NOT PASS 100% (full) charging because THE MAY EXPLODE VIOLENTLY!!!! - BE CAREFULL .... ( Charging Lithium-Ion Batteries – Battery University )

    I've tried toi be sucint, due to that I've written a lot... sorry about that, but I haven't found nothing on this matter anywhere else and I thought that while you guys helping me out with the basci qquestins I've posted in the last paragraph I could give a good ideia for those of you who haven't thought of it!

    Greatings from Azores (the small islands in the middle of the atlantic ;)

    2013-05-12 06:33 AM
  2. DC_Dave's Avatar
    Hi, sounds like a faulty lead, have you tried another? Either that or you are getting induced voltages in it. Acting a bit like an aerial, picking up electrical noise. You could try a couple of 10nf decoupling capacitors from the D+ and D- to screen or 0volts.
    2013-05-14 12:00 AM
  3.'s Avatar
    Hi, sounds like a faulty lead, have you tried another? Either that or you are getting induced voltages in it. Acting a bit like an aerial, picking up electrical noise. You could try a couple of 10nf decoupling capacitors from the D+ and D- to screen or 0volts.
    DC_Dave... I understood perfectly what you've said!

    BUT INDEED this is not something that I want to avoid...(my iPhone 3GS charges perfectly in any USB or charger etc etc, without me having to add resistores to put the correct voltage in de D+ ad D- pins ...(this wya I can een leave them discnoected but of course they-re conected and it serves as a Data cable as well as a charging cable!...

    What I want to know if this's something only o my phone or somebody else has this situation... (because everywhere I go it's something that it's really neded to be done is to hae the corrweect voltages in D+ and D- otherwise we will get the message:

    "device nos supported for charging!"

    ..... probably it's like you said...(the induction may induce a voltage in those pins...BUT wouldn't it be somwhat of a gret coincidence that the voltage induyed with be ealmost exactly the 2.0 Volts that D+ 6 D- requeire to charge drawing 500ma ?....(it would be a really uhge coincidencae since I've tried in oter phones puting mor or less10% and the charger wouldn't charge giving the message I stated above!...

    SO...this is good!...what I'm trying to understand is if this is something just of the iphone 3GS of if it is soethjing of only MY iphone 3GS!

    thbaks for the answer ( really made a good point)

    2013-05-14 03:04 AM
  4. DC_Dave's Avatar
    Hi, I will test it out on a Friend's 3GS next week and get back
    2013-05-14 09:47 AM
  5.'s Avatar
    ....just to supply more data:

    * i've used a borrowed ORIGINAL APPLE CHARGER And it charges as it should;

    ... Thanks as soon as you know something ler me know... Thanks a lot indeed
    Last edited by [email protected]; 2013-05-14 at 11:08 AM.
    2013-05-14 10:26 AM