Brunton ALLDAY Extended Battery Back for GoPro HERO3+
This attachment to the back of the HERO3+ housing extends the GoPro's battery life up to 4x, boosting it by another 4000mAh. Because the battery seals the back door, the GoPro housing will retain an IPX5 water-resistance rating, which means it is suitable for use in the snow, rain, or mud―it will not be fully watertight for use underwater, however.
Not just for extending the battery life of a GoPro, the F-ALLDAY features a USB power port so you can use it as backup power for a smartphone or other mobile device. It also includes a 3-in-1 cable with adapters for Apple Lightning, Apple 30-pin, and micro-USB terminals. It can be charged with the GoPro's charger, or just about any other USB power source.