Maximum output current from USB smartphones

Question

The output voltage of the USB port is 5 V, and it cannot be changed, is it ?!

But what is the maximum current that I can drain from a smartphone? Does it depend on battery, hardware or OS limited? Is there a difference between Android / iPhone / otherOS phones? Can I control the output current using the application? And if the phone is rooted?

An important example: what is the maximum amount of current Iphone 6 can provide with USB?

Answer 1

The official maximum current at the USB 2 OTG input is 500 mA, and the minimum is 8 mA when the port is in host mode.

Source http://www.usb.org/developers/onthego/otg1_0.pdf # 2.5

Answer 2

The USB 2.0 specification allows you to output voltage from a USB port anywhere from 4.40 to V5 and 5.25 inches, but usually 5 V.

While you can build a USB port with a different voltage, you probably should not do this, because the regular USB device that you plug into this port may be malfunctioning or damaged. It is unlikely that your phone provides a function to change the voltage of your USB port.

The USB specification allows devices to dial 100 mA from the USB port before they reach the “configured” state (see Chapter 9 of the USB specification for more information on the status of USB devices). Once the device is configured, it can gain more current if it does not exceed the amount of current specified in the configuration descriptor.

If your phone does not receive the device in the configured default state, it may be possible to write an application to do this, which allows your device to draw more than 100 mA without violating the USB specification.

Answer 3

As reported this iPhone 6 and 6 plus may be able to supply current of about 1 ampere at a voltage at which they are charged . Although I cannot be very sure of this, if the specification of the USB drive used is not indicated.

3A currents seem to be too much. If it were possible, they could use it to charge mobile phones faster (I don’t know if they use 3A chargers or not, but this can be seen on their charger on the output tag).

I would not have conducted such an experiment until I was very sure of this.

Disclaimer: no matter what experience you do, you do it at your own peril and risk. In the answer above, I simply tried to explain what I would do, and gave reason for this.

Answer 4

A list of USB standards and their rated voltage / current values ​​are shown on wikipedia

Nexus 5X and 6P are apparently the first phones to support power transfer via a USB Type C connection: Link However, there is conflicting information about how well it is implemented.

Your 3A output current target seems to be possible with a USB-PD , but it looks like no smartphone currently supports this.

Answer 5

Not sure what you are trying to achieve ...

iPhone 6 may provide some (limited) power for devices connected to the lightning port (it does not have a USB port).

There are cables that connect the phone to the host computer (or charger) via USB, but you will not receive power from the phone in this way (only the power in the phone).

The lightning connector uses active electronics inside the connection cable to force the phone to assign functions to different contacts. It also uses authentication, which prevents you from doing anything for yourself without Apple. To get the necessary documentation, you need to join the MFi program . NDA is involved there, and Apple is known for such things, so you are unlikely to find reliable and / or verifiable information at the Lightning office before joining the program.

See also here .

Answer 6

A unit depleted from a power source is proportional to these factors:
1- The impedance of the device (including batteries and other feeder circuits).
2- Internal device current limiter.
3 - limitation of the maximum current of the power source.

Power supplies

usually provide less current than is dictated by the device. If they provide more, their constant voltage, i.e. 5 V, drops below its standard. Therefore, the restriction is primarily related to supply. The devices provide you with another current limiter to reduce the risk of using non-standard power supplies. I'm not sure if you can change the maximum threshold of the internal current separator to drain more energy or not, but I'm sure you cannot change it in your power source.