Internal 4-cell battery,

Lenovo 5B10W51899 is a four-cell internal battery for compatible Lenovo ThinkPad laptops, designed to fit inside the notebook rather than serve as an external power bank.

Using Li-Polymer technology, it has a rated voltage of 15.48 V, a capacity of 3390 mAh and an energy capacity of 52.5 Wh. These figures describe its electrical characteristics and stored energy.

Compatibility includes ThinkPad T14 Gen 3 (21AH/21AJ and 21CF/21CG), P14s G3 (21J5/21J6 and 21AK/21AL), P14s Gen 4 (21HF/21HG and 21K5/21K6), and T14 Gen 4 (21HD/21HE and 21K3/21K4). It is intended as an internal replacement battery for those notebook configurations.