2017 iMac, is iPhone charging speed different with thunderbolt vs USB-A port?

[johannnn]

I have an iMac which is "Retina 5K, 27-inch, 2017".
When I use the ports on the back to charge my iPhone 14 Pro, I can choose between USB-A ports (and use Apple cables from previous iPhones which I still have laying around) or the thunderbolt ports (with the USB-C cable you get in newer iPhones).

- Is it known how many watts I can charge the iPhone if I use the USB-A or the thunderbolt? I don't know if Apple limits the ports for whatever reason.
- What if I use Apples magsafe charger in the thunderbolt ports, how many watts would I get from that?

 

[Slartibart]

I do not know, but my educated guess is yes - thunderbolt 3 can deliver more power than USB 3 .x via an USB-A connection, it’s 150 mA in USB 3.0; do not have the thunderbolt 3 number at hand.

You can actually check this using the system information: connect the iPhone, open system information and select the bus it is connected to, you should see the current mA.

 

[johannnn]

You can actually check this using the system information: connect the iPhone, open system information and select the bus it is connected to, you should see the current mA.

I had no idea! I will test both reports and post back here.

 

[johannnn]

I do not know, but my educated guess is yes - thunderbolt 3 can deliver more power than USB 3 .x via an USB-A connection, it’s 150 mA in USB 3.0; do not have the thunderbolt 3 number at hand.

You can actually check this using the system information: connect the iPhone, open system information and select the bus it is connected to, you should see the current mA.

I just connected my iPhone 14 Pro to my personal M1 iMac (the Intel 2017 model is my work iMac), via an Apple USB-C cable from the M1 iMac to the iPhone 14 Pro.

This is what System Information says:

I'm a little confused what number I should look at.
I'm located in Europe with 230 volt.
I thought watts = volts * amps, but 230 x 0.5 or 230 x 1.9 or 230 x 2.4 is +100W, whereas I thought the number would be either 5W (slow charging) or 20W (fast charging).

 

[Slartibart]

I am sufficiently certain that the USB 3.1 connection on your Mac does not provide 230V AC. 😄

 

[gilby101]

I thought watts = volts * amps

5V * 500mA = 2.5W.

The maximum with USB 3 is usually 900mA (enough for a low powered HDD). Thunderbolt can deliver 15W - but only to Thunderbolt devices. The iPhone is USB 2, so connects as a USB device.

My iPhone draws 500mA on USB 3 (USB-A) port.

 

[Nguyen Duc Hieu]

I have an iMac which is "Retina 5K, 27-inch, 2017".
When I use the ports on the back to charge my iPhone 14 Pro, I can choose between USB-A ports (and use Apple cables from previous iPhones which I still have laying around) or the thunderbolt ports (with the USB-C cable you get in newer iPhones).

- Is it known how many watts I can charge the iPhone if I use the USB-A or the thunderbolt? I don't know if Apple limits the ports for whatever reason.
- What if I use Apples magsafe charger in the thunderbolt ports, how many watts would I get from that?

You can buy a USB-C to USB-C adapter with powermeter LCD to measure voltage and ampere value of the charging current to your iphone.