AEE DB47 External Battery Pack for S Series
Good complementary battery
I have not run it fully but it does seem to prolong the battery time at least 2 h. I am very pleased with it as otherwise I can change the battery but I need to pause the recording, open the camera, take out the used battery and replace with a fully charged one. In this way, the recording time is much longer. The only minus is that the screen is not compatible with the external battery.