I have used both the NiMH 1.2 V AA batteries that are the radiosailing.net site and Blackube Lithium 1.5 AA batteries from https://www.amazon.com/Blackube-Rechargeable-Batteries-Lithium-1500mAh/dp/B07D9K2H9H. Both are rechargeable. There is about a 50 gram weight difference between the two. Blackube are lighter but 4 are over the class weight minimum. Both last more than 3+ hours of on the water time. Neither have shown signs of being out of charge.