I did replace the protection board, as it did keep playing up. (I started another thread under Electronics.) These are individual protection boards, designed to be used for one individual cell. As you can see I coupled them in serial mode.
This set-up seemed to work better, so I put it together and took it to Jack’s Calusa Creek.
(Sorry for the additional background in the first part.) The sound is Mylocosound Lite Diesel option 2, Rustom Hornsby 4-cylinder.
So it is done. Just need to tidy up the wires, make a [something] to hide the reversing switch on the roof, add the driver and her seat (it got broken when I was moving the battery under the front, and I think her legs are no longer going to fit,) and glue in the windows.