One of my trikes was doing that, turned out the battery was making a poor connection to it's cradle. That battery is what I think is called a dorado style, might be wrong on that but it loads from the side. The fix was using a couple velcro straps wrapping around the battery and frame to keep it tight. Plus I have moved that battery over to another homebuilt and positioned it in a direction where down makes the battery fit into it's socket naturally.