I have a home-brew Hymek weighing 3kg and with an inefficient Cardan shaft that works fine on AAAs, but I am really thinking of the rest of the train weighing 2kg. (I.e. plastic). Obviously more would be good, but I would still be tempted at 2kg. It seems to me that the ability to start on a hill is the critical thing. Would it require the full 12V? Or start to crawl by 9V at most?
I had thought Lithium would be the way to go when I started, but so far AAA or AA have been more flexible in space. And they are a bit less scary to use. But does anyone know what space there is for batteries?
Ta.