That looks great - and by coincidence my 12v flight-box battery seems to be running out of steam at the moment, so your idea is very interesting to me. But before I do anything: Most of us drive cars to the flying field which have a perfectly good 12v batteries on-board, so why don't we just use an extension cable from our car battery to our model's starter motor (assuming we can park our car close to the pits, of course) - do you think would this work? If so then I can do-without a seperate flight-box battery, yes? Tony