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My friend and I both have droids and we often user each other's wall chargers out of convenience. I was told that it's possible that my phone might explode if it's charged with a charger that wasn't built specifically for my phone. How true is this across droids?

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See also android.stackexchange.com/questions/4494/… –  GAThrawn Sep 13 '11 at 22:58
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Don't most modern electronics have overcharge protection circuits? The current should be impeded automatically once it exceeds a certain level, shouldn't it? –  DavidAP Sep 14 '11 at 2:10

4 Answers 4

up vote 6 down vote accepted

While this is standard cover-your-assets boilerplate, the truth is you can charge your phone off of pretty much any USB charger out there, as long as the following things are true:

  • The output specification is +5V DC, and at least 500mA. If it's more (700mA, 1000mA) you are generally fine; the phone will only draw what it needs. My HTC Magic's "official" charger is 5VDC 700mA.
  • The data pins in the charger are shorted (most modern chargers will work. If an iPhone charges off the usb plug with its cable, it means the data pins are shorted).

If you use a car charger, do not get the cheap ones. Car power is a lot noisier than household current, and you need a charger that can survive crank (starting the engine).

If you live in a country where power is unreliable, you may want to charge off a UPS or other power conditioner.

I have charged successfully with a Garmin GPS watch charging brick, the charger from an older smartphone (FreeRunner), and the USB outlets at Southwest Airlines waiting terminals (although I'd turn off USB debugging and USB mass storage before using a public USB charging kiosk.)

If you don't trust it, don't use it! Phones are expensive.

If your device DOESN'T charge off of USB (Pandigital Novel)...check the plug size and the output specification.

If your device uses a funny plug (B&N Nook Color - it's MicroUSB, yes, except that their plug in their cable is longer), then you need that cable.

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+1 for disabling USB debugging. –  theTuxRacer Oct 15 '12 at 9:35

In traditional electrical terms, it is always better to oversize the wattage of a power supply to at least 125 percent. So, if a smart phone uses 700 mA, then a 700 mA charger is at the tippy top of its capacity and could possibly fail. 1 A (a.k.a. 1000 mA) is safer. The phone will only draw what it needs.

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yes, it is absolutely safe to charge a device with a charger that has more current capacity than needed.

Ohm's law tells us the relation between current, voltage, and resistance:

I    =     V      /     R  

(current = voltage / resistance) Since the voltage is held constant (5V), the only factor that determines current draw is the load (another term for resistance) the device places on the charger. Thus, the device will only draw as much current as it needs and no more.

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Droids? as in Motorola Droid phones or Android phones?

To the point, check the specifications on the chargers, if they're the same there's no danger. Most of the chargers use a 5V line to be compatible with USB charging but the amperage may differ. For example, Galaxy S uses a 0.7A charger, and Galaxy Tab 10.1 uses a 2A charger. I wouldn't try to charge my Galaxy S from the 2A line, but it would be ok to use a lesser amperage for the tab, but this would result in a lower charging efficiency.

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The device will only draw as much current as required (certainly in the case of the Galaxy S, almost certainly for all other android devices), so you would be entirely safe using a higher current Micro-USB changer. –  AlexWilson Sep 14 '11 at 4:20
    
Maybe it charges just what it needs, dissipating the rest as heat? Could it overheat? –  Jon Nov 7 '12 at 19:29

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