Saturday, 30 December 2017

usb - Can I use a charger with more output amperage than the device needs?


I've just bought a portable battery, but the portable battery don't comes with an adapter for the house current; it only comes with a USB cable so I can charge it with my laptop. My mobile phone came with a charger, and I want to know if is safe to use that charger with the battery without problems, even though the output has a higher amperage. These are the specifications:


Battery input: 5V, 1A
Charger output: 5V, 2A


Will the output only give the quantity that the input is requesting, or will the input overheat because it cannot handle all the current it receives?



Answer



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.


Speaking from personal experience, I've had no problems charging my phone (which only draws 700 mA) with my Kindle charger (850 mA) or my iPad charger (2.1 A).


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