I did understand, and I agree. I was just illustrating the reason why its perhaps harder to standardise on a particular type of battery (size, shape) for every single ebike, than it is to standardise on petrol or another liquid.
Infact from a bike design point of view the battery is more like a fuel tank (the carrier) than it is like petrol. Imagine how restrictive car design would be if each one had to use exactly the same fuel tank.
I didn't want to suggest that you hadn't understood, Maestro! Sorry if that's how it came across. I was just trying to reiterate my point. You're exactly right in saying that the battery (or at least the case) is more like a fuel tank. What I'm suggesting is wouldn't it be nice to be able to open said fuel tank easily and swap dead cells for new ones that you could buy at any supermarket. Wishful thinking on my part no doubt, but a good marketing point for any ebike manufacturer I'd say.
The problem with the D cell where lithium is concerned is that it wastes space. Unlike many other types, lithium cells can be any shape and therefore utilise all of the internal space of a case for capacity as in the eZee battery with it's ten rectangular cells.
I take your point Flecc about the relative bulkiness of D Cells and the advantages of Lithium Cells from a design point of view. Perhaps D Cells were a bad example, but they're a very well established form factor that everyone understands. One could argue that Form should follow Function, rather than the other way round and that it's up to designers to come up with 'imaginative solutions' within the limits they're set (in this case the D Cell), rather than making a custom battery every time they want to sell a new bike. After all, the motors between bikes don't vary much.
In fact the battery might yet be a dead end for vehicles, all of them perhaps using fuel cells eventually.
I'm hoping that Ultracapacitors might be involved - just think, almost unlimited lifespan and rapid recharging times!
What you describe is absolutely standard for an emerging technology. Each party involved says "the solution is absolutely obvious, everyone must adopt our way of doing it". Getting past this attitude is one of the hurdles on the way to something the consumer will accept.
Using an analogy (HD DVD vs Blu-Ray) perhaps its time for some of the bigger ebike sellers (Kalkhoff, Giant, Ezee etc) to join up and force a battery standard onto the market, give it a catchy name that the public can remember and ask for when buying a bike, and then watch the competition whither away.
Thanks by the way to all those contributing to this thread.