Can 18W USB-C PD Charge a MacBook Pro?
The short answer is that 18W USB-C PD chargers can charge a MacBook Pro, but they may not do so as efficiently as a higher-wattage charger would.
Understanding Charging Capabilities
For 18W USB-C PD to charge your MacBook Pro, it is essential that the charger supports the correct voltage and sufficient wattage. However, 18W is typically insufficient for charging a MacBook Pro due to the power requirements. A 18W charger usually operates at 9V or 12V, whereas a MacBook Pro often requires a higher voltage like 19V for optimal performance.
If the voltage is correct, the 18W charger should work, but the charging speed might be significantly slower than with a higher wattage charger. Meanwhile, the laptop would gain charge more quickly when it is powered off compared to when it is powered on with active displays and disk usage.
Practical Scenarios
Personal experiences differ based on the model of the MacBook Pro and its specific power needs:
A 2016 MacBook Pro can indeed be charged using a 18W charger, albeit slowly. In idle state, it might charge very slowly but gain more charge over a lunch break when the lid is closed.
A more powerful 2021 MacBook Pro might not recognize a 18W charger, or if it does, it may not charge efficiently. The idle power draw of such a device is often close to its rated wattage; thus, an 18W charger might not suffice.
A 2016 MacBook Pro charged from a 18W charger in an almost idle state might charge even faster than in the old one, because the display is less power-hungry. However, the exact outcome can vary based on the specific model and components used.
Best Practices for Charging
While a 18W USB-C PD charger can charge a MacBook Pro, it is not recommended to use such low-power chargers as primary charging devices due to efficiency and potential risks.
MacBook Pros come with a 20V 60W-100W charger for a reason: to provide efficient and stable charging. A 18W charger with 9V/12V might not work optimally, as it will not provide the necessary voltage for higher-wattage devices.
For example, charging an iPad Pro with a 15V 30W charger works well, but using a 9V 18W charger might cause the charger to overheat. Using a charger with more wattage than the device draws regularly ensures that the charger is not under too much strain, leading to better durability and reliability.
Considering the MacBook Pro is a relatively expensive device, investing in a more powerful charger is a sensible choice.