Juniper Systems Allegro MX User Guide - Manual (Page 9)

6. Plug the wall charger into the Field PC power jack located
at the top of the case. The Charge Settings screen opens
requesting you set the charge percentage. Select Enter
percentage and capacity, set the battery charge to 10%, and
leave the battery capacity at 4000.
7. Charge the battery pack at room temperature for at least
6 hours.
Ch 1 Getting Started