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Question about charger(s).

Discussion in 'Android Devices' started by elanning, Sep 10, 2011.

  1. elanning

    elanning Newbie
    Thread Starter


    Simple question, I hope. I am migrating from a Droid X to the Bionic. Can I safely use the various chargers I have from the X? Wall chargers, car charger and so forth.

    Looking at the tiny text on the chargers it looks like they use the same voltage, but I freely admit that I am ignorant about what that really means.

    My uninformed opinion is that a usb charger is a usb charger, but I don't want to risk damaging my new Bionic.



  2. sj993

    sj993 Newbie

    I upgraded from the X to the bionic, using the same charger from the X. I'm pretty sure they are the same, no issues yet.
  3. HotDawg

    HotDawg Android Enthusiast

    No issues, but some chargers are weaker than others and will take you longer. I have successfully used the cord from my OG Droid dock and a plain old USB cord in addition to "Bionic" chargers.
    elanning likes this.
  4. arnould

    arnould Member

    no issues I actually read somewhere that in europe all future phones will use the same charger so that people stop throwing old ones out to replace them. Usb chargers like in androids are the future for phone chargers.

    Java Programming
  5. Vehtemas

    Vehtemas Android Expert

    All chargers use the same voltage via PC/Wall.

    I must admit I now own about 6-7 chargers hahaha.

    And 2 car chargers.

    All of them fit and work like a charm.
  6. CKwik240

    CKwik240 Well-Known Member

    Voltage should be the same for all USB power at ~5V. There are a very few exceptions, but phone chargers are unlikely to be one. The big difference is going to be in the current output. The Bionic has a 850mA charger at 5.1V. I've seen non-smartphone and BT headset chargers rated at much lower current (150mA to 500mA). Basically, the higher the current, the faster it can charge. The device ultimately determines how much of the current it can use. And one factor in that is if the charger has the proper protocol for signalling to the device that it is a dedicated charger. Basically, current is limited by the device if it thinks it is pulling power from a computer's USB port as a high current draw from a computer could damage the computer. The signal is usually just a simple short between the 2 data terminals of the USB charger. There appears to be a more complex signal available as well, but I couldn't understand the schematics in the USB specifications sheets.

    As for damaging your phone, I wouldn't worry about it too much. So long as the voltage is around 5V, the phone want draw more current than it is designed to. I have several 2100mA chargers around the house for my Galaxy Tab and they work fine with my DroidX, girlfriend's Dinc and even the Bionic. I also have a couple of 2.1A chargers in my cars.
    johnlgalt likes this.
  7. johnlgalt

    johnlgalt Antidisestablishmentarian

    Yup - exactly. USB cables connected to Computer USB ports should, for the most part, be limited to 500 mA maximum. The only time an exception might pop up here would be if you have a powered USB hub - IOW, a USB hub that has a separate power source rather than that of the computer's main USB port that the hub plugs into.

    Also, other power sources may be able to supply more current than the 500 mA that is the USB standard. However, as CK mentions, the BIONIC will only pull 850 max. So trying to decide between two chargers whose outputs are, say, 1A and 1.2 A, is useless - neither will supply any more power to your BIONIC.
  8. CKwik240

    CKwik240 Well-Known Member

    A powered USB hub likely won't provide the signal to tell the device it can pull more than 500mA. So if the device isn't asking for more than 500mA, then regardless of the hub's actual current supply capabilities, there will only be up to a 500mA supply to the device. A separate power supply to a hub is usually done so multiple devices can pull 500mA from the hub. If you tried to power a combination of devices that pull more than 500mA current total from the hub and its only connected to the computer, then the computer would have to try and provide the sum of the currents to the hub.

    Its possible the Bionic can pull more than 850mA. I can't say for sure without testing it during a charging cycle, but unless there is a limitation designed into the phone or inherent of its design and depending on what that limitation on the phone is, it will pull as much current as can be provided by the supply until it reaches its own limit. Perhaps I'll finally get around to testing this soon to see where its at.
  9. sober

    sober Lurker

    OK......charge circuitry/logic is built into lithium ion batteries. No li-ion cell should ever be charged at a rate of more than 1c (ie, a 1700 mah cell should not be charged at a rate higher than 1.7 amps). Minimum cell voltage is about 3.2 volts, Max is 4.2 volts.

    The phone does not PULL from the charger. The supplied charger feeds 5 volts at 850 ma rate, which will equal full charge in approximately 2 hours. I have Motorola chargers from several different phones, all output same voltage and current.

    When the built in circuitry in the cell sees voltage nearing 4.2 it will limit input, then break the charge circuit once 4.2 volts is reached. Because of this your phone can stay on charge indefinitely, as it will charge only when voltage drops below approx 4.2.

    It is difficult to accurately tell state of charge with these lithium cells. The software that displays charge level must know the maximum charged voltage, and the minimum voltage at phone cutoff then it can accurately give a reading. This is why it is important to run the phone til it shuts down on its own, not because the battery needs to be cycled as so many posts would have you believe.

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