The HP L78551-005 is a 3-cell internal replacement battery listed for the HP EliteBook 830 G7 series. It powers the laptop when it is not connected to an AC adapter, making it a service part for replacing the corresponding battery in a supported laptop.
Its stated energy capacity is 53 Wh; the product listing identifies lithium-ion chemistry and a charge capacity of 4.59 Ah. These specifications distinguish this battery variant. HP’s service procedure shows it installed inside the computer, connected to the system board and secured in place.