Nikon has published a compatibility notice regarding the EN-EL14a lithium-ion battery. In short, cameras compatible with the older EN-EL14 battery are compatible with the new EN-EL14a battery (although some require a firmware update).
What Nikon fails to mention in the compatibility notice is that upgrading your camera's firmware may cause your camera to be incompatible with third-party batteries
The EN-EL14a rechargeable Li-ion battery can be used in place of the EN-EL14 rechargeable Li-ion battery.
The EN-EL14a battery life has been improved by up to 20% compared to an EN-EL14 battery (depending on the camera model and shooting conditions). Both batteries can be charged using the MH-24 battery charger.
All cameras that currently use the EN-EL14 can also be used with the EN-EL14a. See the following for further information regarding EN-EL14a compatibility with each camera.
D5200, D5100, D3200, D3100, COOLPIX P7700- By upgrading firmware, EN-EL14a performance is maximized and more images can be captured (battery performance) when an EN-EL14a is used than when an EN-EL14 is used.
- D5200 - Firmware C: 1.01 or later
- D3200 - Firmware C: 1.02 or later
- D5100 - Firmware A: 1.02/ B: 1.01 or later
- D3100 - Firmware A :1.02/ B 1.01 or later
- COOLPIX P7700 - Firmware version 1.3 or later
- COOLPIX P7000 or P7100 - Although firmware enabling support for the EN-EL14a will not be released, the battery can be used with these cameras. However, the camera's battery indicator may quickly reach the half-charge point on its display.
- COOLPIX P7800 - The camera already supports the EN-EL14a from the time it was initially released, so does not require a firmware update.
- Nikon Df, D5300, D3300 - An EN-EL14a is included with purchase. The EN-EL14 can also be used with these cameras.
B&H carries the Nikon EN-EL14a battery.