Lenovo Battery Internal 4 Cell 72Wh LiIon

The Lenovo 5B10W51887 is an internal lithium-ion battery for a laptop. Its four cells and 72Wh rated energy identify the battery’s configuration and capacity. Lenovo associates this part number with model L21M4P77 and specifies a battery voltage of 15.52V.

Designed to fit inside a compatible laptop, it is a replacement power component rather than an external power bank or mains adapter. Its internal format makes it relevant when restoring a laptop’s built-in battery power source.

The part number helps distinguish this battery from similarly numbered parts with a different model or rating. The 72Wh capacity is a useful reference when checking the part against technical or service records.