Update - The HyperJuice is able to charge the PPMax to 100%.
PPMax in Normal mode and only showing the shortcuts screen.
11:12am - 84%
11:42am - 91%
12:12pm - 98% (approx. 14% in 60 minutes)
12:25pm - 100% (LED red)
At 100%, I power off the PPMax but left the charger connected. The LED still remains red. I did not wait longer to see whether it turns blue.