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Can dumb / feature phones be charged using USB?

  1. May 14, 2014 #1
    Hello,

    I recently received a USB power pack but I can't seem to charge the dumb / feature phones that I have. When I use this adapter to connect the phones they say that they are charging but even after 5 hours they seem like they didn't get a charge t all.

    Is the voltage difference the issue? With the USB being 5V and the phone battery being 3.7V (though the output of the chargers that the phones came with is 5V).

    Could I have a faulty unit?

    I'm trying to find out what the mA rating of the USB port is but the supplied wall charger is 5V 400mA so if the USB port is providing less amps than that it won't charge properly?

    Also, because the battery in the power pack as well as the batteries in all the phones is 3.7V what would happen if I remove the USB port and wired that 10 in 1 adapter directly to the battery?

    Thanks for reading.
     
  2. jcsd
  3. May 14, 2014 #2

    AlephZero

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    Is the phone designed to be charged from a USB port? If not, the maximum current may from the port may be limited to 100 mA which will take 4 times as long to charge it as your wall charger. Or even worse, the USB port might not even "know" you plugged anything into it and it won't supply any current.

    I wouldn't try that, unless you don't might frying either the phone or the computer with the USB port :eek:
     
  4. May 14, 2014 #3

    meBigGuy

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    Post the datasheet for the battery pack. Also, what phone models you are trying to charge. Maybe there is a simple answer (but that's unlikely). Generally the battery packs short DM/DP indicating they are a dedicated charger. But not all phones follow that prorocol.

    Different phones have different protocols for determining how they will charge. If you are charging an iPhone, you need an iPhone compatible charger with the proper resistors attached to DM/DP.

    For example, I recently plugged my dumb phone into a real USB and it wouldn't charge until I shorted DM/DP (which I don't recommend you do)
     
  5. May 15, 2014 #4
    The phones weren't designed to be charged by USB port, but like I said because the wall chargers for both phones have 5V output I thought that they would charge when plugged into the battery pack.

    As I received it from a relative I don't have any instructions and / or a data sheet for the unit. I've tried contacting the manufacturer but they didn't get back to me. It's a cheap Chinese model. One of the phones is a Nokia 1616 and the other is an Alcatel one touch 232, the current output from their respective wall chargers are 350mA and 400mA.

    What about this:
    Remove the USB port from the battery pack exposing the 5V leads, cut a spare wall adapter and attach it's wires to the battery pack, connect phone.
     
  6. May 15, 2014 #5

    meBigGuy

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    There shouldn't be any difference between 5V from the battery pack USB connector and 5V from inside it. It's hard to say what is really happening withut making measurements. What you need to know is whther there is 5V on the proper pins at the phone when the battery is connected (I assuming the phones have circular connectors). If there is 5V then I have no idea what is happening. If there isn't (because the battery pack is shot), then I'm surprised that the phone says it is charging.

    If the phone's don't have circular connectors, then it's hard to tell what is really happening, but you still need to verify the pack is actually supplying 5V when current is being drawn.

    At this point I'm guessing the battery pack is shot. Is there anything it does charge correctly that would contradict that?
     
  7. May 16, 2014 #6
    If the right voltage isn't being supplied how can the phones even say they're charging?

    I don't think the battery is in bad condition my hypothesis is that there is a problem with the usb circuit of the device. I say this because there is a 1W led built into the thing and it works for the duration that the battery capacity says it should.

    I tried to open it up today but I'm having a hard time doing it without breaking the outer casing. I'm going to take it over to someone during the weekend to let them try and open it for me.

    https://usedcellpro.com/18-59-large/mini-usb-home-charger.jpg [Broken] 31VT7597NGL._SY300_.jpg

    Apart from the type of plug these are basically the chargers I have.

    I also connected a Nokia 5800 which has a 5V 890mA wall charger and it acts the same as the other two.
     
    Last edited by a moderator: May 6, 2017
  8. May 16, 2014 #7

    meBigGuy

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    The type of plug is important.

    If it is a square plug, the phone will want to follow some "square plug protocol" (not always USB) that is compatible with its stock charger. That may be, for example, a particular voltage applied to one of the USB data pins.

    The round plugs are generally just raw supplies (although I can't say that's always true).

    The following part illustrates the complexity. http://datasheets.maximintegrated.com/en/ds/MAX14578AE-MAX14578E.pdf Figure 3 on page 16 shows some of the options. I think Nokia is even different.

    The most standard is to short the DP/DM pins (sometimes called D+ D-). If you are plugging into a square plug, at a minimum D+ and D- should be shorted. But, who knows what your battery is doing?
     
  9. May 17, 2014 #8
    The manufacturer finally got back to me and and said that it's 500mA.

    For now I'm thinking of using something like this (with an adapter that'll fit the Nokia 1616)

    $_103.JPG

    Connect the wires to the 5V supply in the pack and see if the phones actually charges.

    Would this be a good idea?
     
  10. May 18, 2014 #9

    meBigGuy

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    I doubt very much it will make any difference.

    If you are going to open the pack, then first measure the voltage at the connector when the phone is charging. If it is 5V, then the phone doesn't like the charger. If it is not 5V, then the battery pack is shot.

    You could build an adapter so you can measure the voltage while the phone is connected, without opening the pack.

    I would not modify anything without know exactly what is happening now.
     
  11. May 18, 2014 #10
    Thank you for your advice.
     
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