How do I charge the EverStart Maxx 1200A Jump Starter for the first time?

The unit is delivered in a partially charged state and must be fully charged before first use. Insert the barrel connector of the AC charging adapter into the AC charging port on the front of the unit, then plug the adapter into a standard 120V 60Hz outlet. Charge for approximately 20 hours or until the Battery Status Icon shows 4 solid bars. (Page 6)