Charging MacBook 12" with a battery pack

Charging MacBook

Battery Pack charging via USB C 

The new MacBook 12” comes with a USB-C port that handles all processes of data transfer and charging.

I experimented with the XiaoMi 5200 mAH battery pack with a DC 5.1V/1.5A output. 

In order to charge the laptop with the above mentioned battery pack output, I found that the MacBook battery level has to be under 24%. Once the battery level hits 24% the battery will stop charging. 

This is due to the MacBook’s wattage. It will overpower that of the battery pack, causing a reverse charge instead. 

Should the battery pack remain connected to the MacBook at a battery level of above 25% I can confirm that a reverse charge will initiate and drain the MacBook's battery instead.

So battery packs are good to sustain the MacBook's battery life while in use but not enough to actually charge it completely unless you turn the MacBook off.

This method will only come into handy in the event that a wall plug is not within reach and you need to get more work done on the laptop. 

Technically speaking any work you can get done on the MacBook can be achieved on an iPhone as well as the MacBook is not really good or powerful enough to handle anything else, so I would actually save the battery pack's power to keep the iPhone charged up rather than charge the MacBook. This will give you a much better value in overall time to be online.