I am a bit confused about some supposedly basic electronics concepts :/ (I kind of have an answer but just want to confirm)
So let's say I have got this setup:
- A 13A 220V mains socket
- A 13A powerstrip connected to the above socket
- Two 60W 5V USB chargers, such as this http://www.amazon.com/gp/product/B00P936188
Question: If I plug the 2 chargers and fully utilize them (connect all ports to charging iPads), am I overloading the socket?
The spec says it can deliver 2.4A per port, or 12A overall. Simple addition of the amperage is:
12A + 12A = 24A > 13A, so I am overloading
However, the wattage is just 60W so maybe the correct way to calculate it is:
Power = Current * Voltage
Current = 60 / 220 = 0.27A
So the input current is actually just 0.27A so I can actually safely connect as many as 13 / 0.27 = 48 of those chargers to the same mains without problems. The 12A is provided by the transformer inside the charger and doesn't concern the mains circuit.
Which one is the correct interpretation?
Best Answer
You're comparing apples to oranges. You're using the power output, to try and determine the input. Without knowing about the transformer, and other circuitry, that's going to be quite difficult. According to the specification listed by the manufacturer
The unit will draw about 1.4 amperes at 100-240 volts AC (VAC), which I'm assuming is the value when the unit is fully loaded.
The 12 ampere value you're using, is the output current which is at 5 volts DC (VDC).
This unit takes in AC power, steps it down and converts it to DC power. The devices that are connected to it, then draw DC power to charge. The unit seems to be able to supply 12 amperes at 5 VDC, though it's not likely all the connected devices will take advantage of the full available current.
The 60 watts, is the amount of power available on the output side of the device.
12 amperes * 5 VDC = 60 watts