Spektrum 4000mAh LiPo Transmitter Battery: DX8
The 4000 2S LiPo offers not only double the flight time as the stock DX8 battery but also advanced safety and features. It also includes a built in safety current that shuts the battery off, to avoid overcharging and damaging the battery and radio. Plus a built in balancing system to make sure you get the longest life and power from your pack.