Check out this starter pack from HiKOKI, including 1x the latest rapid battery charger for use with Hitachi/HiKOKI Slide On batteries (UC18YFSL), and 2x BSL1840M 4.0Ah slim batteries.
BSL1840M 4.0AH BATTERY SPECIFICATION
Voltage: 18v
Capacity: 4.0Ah
Energy (voltage x capacity): 72 Wh
Battery Level Indicator: YES
Charging Time With UC18YFSL: 60min
Number Of Cells: 5 (1 Layer)
Dimensions: 134 x 83 x 54mm
Weight: 560g
UC18YFSL CHARGER SPECIFICATION
Mains Voltage: 240v
Battery Voltage: 14.4v and 18v
Battery Type: Lithium-ion
Part Number: UC18YFSL