With a recent firmware update, GoPro killed compatibility with third-party batteries. Wasabi Power are out with a new version of their battery that fixes that and promises to be compatible with all future GoPro firmware updates.
Wasabi Power Batteries
GoPros have never had particularly good battery life. So having spare batteries on hand, along with an external charger, can help you keep shooting.
Here’s a roundup of some options for spare batteries and battery chargers for the GoPro HERO 4 Silver and Black editions.