Looking great, I also prefer the one with the tire, it gives it character. I think the more ingenious usage of car parts the better.
The only thing that I would say is that it seems like the battery would eventually slide and fall off with one strap on it rendering it powerless. So I would add more straps and maybe have a clamp/trim below and above it so 'sits' in place securely.
Or perhaps position it at the bottom with the pole sticking into it, which will also spread the weight more evenly and balance it out better.