How does it tell AC vs USB charging?

Discussion in 'Droid 2 Tech Issues' started by wkearney99, Sep 7, 2010.

  1. wkearney99

    wkearney99 Member

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    I've noticed the Droid2 has a little light next to it's USB port. That light only comes on when connected to a wall adapter. It will not light up when connected to a USB hub, computer port or any of several 12vdc car chargers I've tried.

    This is a big problem if you make heavy use of the phone while on a 12vdc source (like running trapster, gps, wifi and navigation while in the car). The battery isn't sufficient to keep the phone running and it won't pull enough juice through the charger to offset it.

    So I'm wondering whether the phone is making a mistake in how it's recognizing the different types of chargers.

    How does the phone know which type of source is connected? The API indicates it can tell AC vs USB. But it doesn't say HOW the answer is determine. And no, it doesn't appear to have a way to show an amperage value, just voltage and that's usually the same on either kind of source.

    So, WTF?
     
  2. DF Smod

    DF Smod Silver Member

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    I had to go outside and test your theory on my D1

    With the original charging cable and a 12V USB Car Adapter my charging light by the Micro USB port came on

    The phone can recognize the USB into a Computer because the computer has a different output than a 12V USB that the phone picks up on, and of course you will never get as good of a charge from 12V V/S 120V but I am sure you know this already...the main thing is that my phone does in fact recognize the car charging system correctly and yours possibly is not

    Hopefully someone with a D2 can test their phone on a 12V charging system, maybe you have a defective device
     
  3. wkearney99

    wkearney99 Member

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    Thanks for checking.
    My attempt was using the new charger from verizon. One that has a second USB port on it.

    True, that and some low end wall adapters are also a problem. I've seen a number of cheap imports that won't provide more than 500mw. Versus the supplied charger is listed as 850mw.

    yeah, that'd help too. Any volunteers?
     
  4. DF Smod

    DF Smod Silver Member

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    The one that came with the phone right...USB on one side and Micro USB on the other and it plugs into the wall block for wall charging ?
     
  5. wkearney99

    wkearney99 Member

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    No, the charger I'm talking about is the one sold in the Verizon store. It has a coiled cable with a micro USB on it. The other end plugs into the 12vdc accessory outlet. On that portion there's also a USB port, presumably to allow plugging some other USB device into it for charging. I used it to charge the iPod we use to play videos on the flip-down TV screen for the back seats. When I connected that to the D2 the white LED did not light up.

    I've got a bunch of USB to micro USB cables now. I honestly don't know which was supplied with the phone. I do know that some of them won't work for charging a blackberry. From the outside the cables look the same, presumably there's some pinout difference between them. I'll have to experiment a bit more to see which of these cables are the BB-capable ones, and whether that affects D2 charging too.
     
  6. wkearney99

    wkearney99 Member

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    Tangentially, I'm wondering about the moto car cradle. Since I can't see the white LED when it's in the cradle, I wondered how I could tell on the screen. There doesn't appear to be a way (at least not in any battery or stats apps I've tried) to see the type of charging. So I can't tell if the cradle is going to do a full charge or not.
     
  7. KnightCrusader

    KnightCrusader New Member

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    I thought I'd add what I know and what I have experienced from charging my phone in the multimedia dock, the computer, AC adapter, and Car USB adapter.

    First, I believe the phone gets 5V sent to it no matter what it is plugged into. The computer takes longer to charge because Motorola actually programmed the phone to behave and follow USB standards by limiting the current to 500mA. The wall charger and car charger do not have this limitation so it pumps as much current as they can and the phone takes what it needs.

    How does it know this? I would assume its the fact that when it is plugged into the computer, the Data lines in the cable are active and the phone talks to the computer and knows to follow USB standards. There is no such communication in the wall/car adapters so it takes what it gets. Thus, the computer charges the phone much slower. I am attempted to try to make a USB cable with the data wires cut or covered and see if I can trick the phone into charging faster when plugged into the computer.

    Also, I have my D2 plugged into my computer as I type this, and the white light next to the port is on. Its on when its charging no matter what source it is from. I'm not sure why yours would only be on when charging from the wall.
     
  8. metroplex

    metroplex Member

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    Just FYI:

    USB is 5 VDC, and there's a limit to the amount of current that can be pulled through: main port on a laptop/PC, powered HUB, unpowered HUB, and a wall charger.

    The Motorola Droid 2's included wall charger converts 120 VAC to 5.1 VDC at 850 mA. I have a Griffin aftermarket USB wall charger for iPods that produces 5.1 VDC at 1000 mA output in USB format.

    The Droid 2 will charge fine from either the Motorola or Griffin chargers. If you can buy extra micro USB cables, any USB wall charger capable of 1A output will work.

    However, I found that my Droid 2 will NOT charge from the USB ports on the Dell Latitude I have from work. I think you need to have permission to install drivers before that PC will charge the Droid 2.
     
  9. xfloggingkylex

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    The only thing I have noticed between wall and usb charging, besides a slightly longer charge time, is I get the rogue screen issue. I am using a hardcase, and when my droid 2 is plugged into my laptop (need to double check other computers), the screen is freaky, like I can't get a long press. If I take the back of the case off that problem goes away.

    The odd thing is that with the case on, if it is plugged into the wall adapter I don't have that issue at all. So there is definitely something different between the two.

    Sent from my DROID2 using Tapatalk
     
  10. Redflea

    Redflea Silver Member

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    My charging light on my D2 comes on regardless of the source...car charger, wall charger, computer usb, portable battery charger. If the light doesn't come on, the phone isn't charging, AFAIK.
     
  11. metroplex

    metroplex Member

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    I just confirmed that the PC must be able to install drivers for the phone when it is connected via USB in order for it to charge. The laptop I have at work is restricted by IT when it comes to stuff that is connected to USB, so I cannot charge the Droid 2 at work unless I bring my wall charger.
     
  12. dbuglio

    dbuglio Member

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    Restricted or is USB disabled in your BIOS?

    Sent from my Droid using Tapatalk
     
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