How to select a power supply for a given Android device There are a variety of products on the market which provide a power supply for Android devices through the ubiquitous MicroUSB 2 port.  These include adaptors for 12V "cigarette lighter" car DC power supplies, adaptors for AC (120-240V) domestic power supplies, solar power supplies, AA battery power supplies, and so on.

One consideration with all such products is the maximum current they can supply.  This is generally 500mA at a minimum, but I have seen up to 2 A.

How can we know what current our device will draw, so as to select a power supply which will maximize its recharge rate?  What is the maximum current that can be supplied via a MicroUSB connection?  How can we know if our device is able to safely use a power supply which can supply more current than it draws?
I'm not aware of any way to find out the maximum current the device will use except checking the charger that came with the device and assuming that the manufacturer suppied the most efficient charger suitable. 

The maximum current for USB connection is 5A, but usually the range used by phone/tablet chargers is between 0.5A and 2A. 

Note that the amperage of the charger only tells what is the maximum current that the charger can supply, so it's safe to plug a 2A charger to a device capable of 0.5A current.