4

Could someone tell me how much Amperes (Amps) the Retina MacBook Pro can deliver over USB?

I thought that one should be able to charge an iPad with a Retina MacBook which would mean that it should be about 1A minimum (probably rather 2-5A for an iPad3). However when I plug in my Android phone to charge, it does charge slower than on an 1A USB charger.

3

Macs with USB 2.0 from the last few years can generally provide 1.0A via USB. The USB 3.0 standard specifies 900mA; I suspect that USB3 Macs still provide 1A or even a little more. Note however, that in order for a device to actually draw that much, it must specifically request it from the bus. Apple's iDevices certainly do this, as you can see in System Profiler (as mentioned in the other answer). For a USB 2.0 device to request more than 500mA, it must implement a special protocol extension, which few devices follow. The reason those devices might still draw 1A from a pure charger is because they detect that the data lines are not connected in the usual way.

Likewise, the iPad only draws 1.0A when connected to a Mac (or even 500mA from most PCs), but 2.0A when connected to the special iPad charger. The charger has its data pins pulled to special indicator voltages via a potential divider, and the iPad only draws that much current if it detects this configuration to avoid damaging whatever it's plugged into.

| improve this answer | |
3

With the System Profiler you'll be able to know how much power does the USB delivers, and how much is required for each device connected to a USB. Under the Hardware tab, you'll find, listed, all the USB ports, and, within, all the devices connected to them. Just select one of those to get detailed information.

To open System Profiler just choose Apple Menu / About this Mac and clicking More Info, or go to Applications / Utilities.

| improve this answer | |
  • "System Profiler" -- easiest way to find this is to use spotlight search; in Sierra the USB data is under "System Report..." button in System Profiler – jcollum Apr 26 '17 at 21:58
2

With a MacBook Pro (Retina, 15-inch, Early 2013)

I got this when charging an iPad, which is 2100mA in total.

enter image description here

| improve this answer | |
  • Where did you get this information? – unom Oct 22 '15 at 22:48
0

I have a Late 2013 MacBook Pro. The output with a iPhone 7 Plus connected to the USB 3 Left port is 1.8 Amps. Verified using a USB power meter dongle. This only happens once the iPhone has booted. Before booting, the iPhone takes only .38 amps.

System profiler shows the following:

Current Available (mA): 500
Current Required (mA):  500
**Extra Operating Current (mA): 1600**
Sleep current (mA): 2100

So it seems the MacBook Pros can indeed output approximately 2 amps. Which should be enough to fast-charge at least the iPhone X.

Mac System Profiler outputs 1.8 Amps on USB

| improve this answer | |
0

The maximum amount of power that your MacBook or Apple Display can provide depends on whether it has USB 2 or USB 3 ports.

  • USB 2 - 500mA
  • USB 3 - 900mA

See Using USB devices with your Mac for complete details.

System Information (Apple menu  > About This Mac) can give you more details about USB power.

  • Current Available is the default amount of power available to your device
  • Current Required is what the device is asking for
  • Extra Operating Current is extra current available to certain Apple devices like iPhones and iPads.

Source: https://support.apple.com/en-us/HT204377

enter image description here

TL;DR

The maximum amount of power is dependent on whether you have USB 2 or USB 3 ports, 500maA and 900mA respectively. However, if you plug in certain Apple devices, there is extra current available which your device can use. It's not generally available to all devices (like Android phones or tablets)

| improve this answer | |

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .