"I had the rudder control on the Tx back to front ..."
He he😂 EXACTLY the same thing happened to me with my Sea Scout Ian.
Had to think backwards on her first run😮
Re BEC! That sounds very logical.
The internal regulator will need at least one volt more than the required output voltage (presumably 5V if it's like my 10A Vipers
) to work.
Another reason I prefer a separate RX battery 👍
When you check a battery OFF LOAD it will always have recovered a little and show a slightly higher voltage than it would on load!
Check it when loaded with something like an old 5W car bulb and watch the voltage.
At 6V the current will be around 800mA.
The voltage will usually drop a little as the load is applied. But if it keeps on visibly dropping then the battery needs charging.🤔
Your motor will draw much more current of course, which accelerates the process.
All's well that ... 👍
Cheers, Doug 😎