I found the
source of the info I was looking for. Turns out there's a different charging hub (don't think it's available yet) called the Advanced Hub to use with a 100W charger that will do partial parallel charging.
3. What is a Battery Charging Hub? What is the difference between the two versions of the Mavic’s Charging Hub?
The two Charging Hubs can both charge up to 4 batteries at one time. In order to fully charge the first battery as quickly as possible, the Intelligent Flight Batteries are charged in sequence according to their power levels, from high to low. This gives you the fastest way of getting all your batteries fully charged. There are two main differences between the two Charging Hubs. First, the standard Charging Hub only supports the Mavic’s 50W Battery Charger and Mavic Car Charger, while the advanced version also supports the 100W Battery Charger and Car Charger from the
Phantom 4. Second, the advanced version will balance the voltage of each battery cell to improve charging efficiency.
When one battery’s charging enters the second-half of its charging phase, the next battery will enter the first-half of its charging phase. With 4 batteries all at 15%, the advanced charger can get 4 batteries fully charged in 140 minutes using the
Phantom 4’s 100W charger, while the standard version will need 270 minutes with the Mavic’s 50W charger.
So looks like we'll be wanting to get both the Advanced Hub as well as the
P4 100W charger once the Advanced Hub is available.