The HP EliteBook 840 G3 battery is a CS03XL model, a Li-Polymer or Li-ion battery with a voltage of 11.4V and a capacity of approximately 46Wh (or 4100-4600mAh). It is an internal, 3-cell battery that is not customer-replaceable
Battery specifications
Part Number: CS03XL
Battery Type: Lithium-Polymer or Lithium-ion
Voltage: 11.4V
Capacity: Approximately 46Wh (or 4100-4600mAh)
Cell: 3-cell
Condition: The battery is internal and not designed for customer replacement, but can be serviced under warranty.