That’s why it’s possible to charge your smartphone off your computer’s charger, but it takes forever to fuel up your computer with your smartphone’s charger. Most chargers boost the standard 5V CLA output to 9V, using the original USB sockets or the latest symmetrical USB-C connection. Plug a smartphone in, however, and it will use one of the lower-power options. In sleep mode, the 12W charger is able to charge the notebook in about 4-5hrs.
Macbook usb c charger voltage full#
So if you plug your MacBook into its charger, it’ll use the full 87 watts. In summary, a 5V/2.4A (12W) charger can keep a Macbook 12' operating continuously, charging it at the same time in slightly less than one day.
Devices have built-in limits and will reduce the current so they’ll only draw as much power as they’re capable of handling. Now, even though a USB-C charger may support it, you can’t just shoot 100 watts straight into your phone and expect it to work. But USB Power Delivery (USB PD), a feature many USB-C devices support, complicates things by enabling “fast charging.” This means chargers with USB PD can generate between 0.5 and 100 watts by operating at 5, 9, 15, or 20 volts, and between 100 milliamperes and 5 amperes.
For USB 1.0, it was 5 volts at 500 milliamperes for a maximum power of 2.5 watts. With the MacBook 29 watt charger and a USB-C to Lightning cable the iPhone sees more power but Apple doesnt say how much more. So, in an effort to get everyone on the same page, the USB standard limits charging to certain ranges. Using a USB-C to USB-A adapter and a USB-A to Lighting cable to your MacBook charger means your iPhone gets no more power than using a common 12 watt USB-A charger, both cases means the phone sees 5 volts 2.4 amps.