Q: It's taking a long time to recharge the PowerPack. Is it okay to use the iPhone power adapter to recharge it?
A: The iPhone power adapter will slowly recharge the high-capacity PowerPack 20000 and may take over 24 hours to fully recharge, so while it may seem the PowerPack stopped recharging, it's because the recharging is very slow. The fastest way is to use a USB-C power brick with a USB-C to USB-C cable. For example, the 2017 MacBook Pro power adapter will recharge the PowerPack 20000 in about 4 hours. If it seems that the PowerPack is not recharging properly, make sure you try using a more powerful charger like the MacBook Pro one or ZMI's 45W charger.
Please also refer to a related FAQ: