The EN-EL25a is a rechargeable Lithium-ion battery that is used to power specific Nikon mirrorless cameras. It has a 10% increase in capacity (7.6V / 1250 mAh) over the older EN-EL25 battery. The EN-EL25a can be charged using the MH-32 battery charger or it can be charged while in the Z 50 camera using the EH-73P or Z 30 / Z fc using the EH-7P charging AC adapter.
The compatible camera's firmware must be updated to the latest version to utilize the EN-EL25a battery. Z fc (“C” firmware version 1.50 or later) Z 50 (“C” firmware version 2.50 or later) and Z 30 (“C” firmware version 1.10 or later).