By "Premium" battery pack, are you referring to Lithium, etc.?
This whole vehicle project is one big low-budget experiment.
I doubt I would ever put any truely expensive battery pack into it.
I might choose to go to a purpose-built vehicle, such as an all-electric
XR3 if I ever put that much money into a project.
I think I am sticking with lead for the foreseeable future.
On a side note. I put my motorcycle's Optima Yellow Top AGMs in the Citicar for this weekend and WON BOTH DRAG RACES! Some variations of lead-acid are still pretty nice.