as this project has dragged on for much longer than it should have and we really needed to get a controller a quick look on eBay found me a suitably rated unit out of China for only $50 which is pretty close to theBOM costs for what I've been doing, so I bought one and have the batteries now under control.
But I'm still curious as to why this project has the periodic lock up problem. So will continue working on it.
To start with one issue that has plagued me has been broken wires between the modules, only becaus the 3 boards were floating in the breeze.
So I've screwed them all to a lump of wood which will hold it all secure while I continue looking into it.
Now it's a bit more secure I can lug it around a bit easier.
some new firmware will be written to allow me to test the switching characteristics of the FET and drive circuit with out haveing to charge and discharge the batteries. I'll start with a square wave with a period of about 1 second and see what result I get.