Editor’s note: This article is part of our roundup of USB-C battery packs.
Adding USB-C on the 2015 and 2016 MacBook models opened up laptop charging without any compromises, as the USB-C standard supports high wattage power and bidirectional power flow. That lets a MacBook charge a device via its USB-C port and also be recharged through the same interface.
USB-C will be coming to the MacBook Pro once Thunderbolt 3 controllers are up to Apple’s specifications, as Thunderbolt 3 adopted the USB-C connector type and is interoperable with USB for power, data, and display connections.
USB standards have allowed a bewildering array of charging possibilities over connectors prior to USB-C, starting below a watt in the older days, then moving into much higher ranges, although still often peaking at about 5W, which is a pretty slow way to charge even a smartphone-sized internal battery. Apple had its own variant of standard USB that let iPhones and iPads charge at higher rates when connected to USB ports on Macs and through AC adapter that shipped with the products.
Even as older versions of USB continued to get charging boosts in shipping equipment, USB-C popped the lid off with a top potential of 100W using Power Delivery 2.0 (PD2)—as long as the right cabling is used and compatible devices are on both ends of the connection. (An earlier PD version can also support up to 100W, but Apple didn’t adopt it, and I can’t find any widespread use of it. USB-C seems to have lapped it.)
Apple even extended USB-C to Lightning for the 9.7-inch and 12.9-inch iPad Pro via an USB-C to Lightning Cable ($25 on the Apple Store). Both iPad models ship with USB adapters that charge at a rate far slower than what their respective batteries can handle. With the cable attached to a 29W adapter that’s included by Apple with MacBooks and also sold separately ($49 on the Apple Store) or a USB-C battery pack, an iPad Pro can charge at or close to its maximum rate.
None of the batteries tested, except the MOS Go, would charge the MacBook while the computer was awake. This appears to be a flaw in the Mac operating system’s battery management, as it only recognizes external batteries as “power adapters.” Apple likely needs to create a new system-wide profile and a new Energy Saver preference pane tab for these battery packs. The MacBook may need more than 15W in its lowest-power mode, but it’s impossible to tell.
I tested with the Mac in sleep mode to allow for a fair comparison. In separate tests with the Mac active, I definitely extended its internal charge, but not consistently enough to be useful. You should plan to be able to sleep or shut down your Mac for 30 minutes to two hours to transfer a useful amount of charge with the current Mac operating system and battery pack interaction.