Wellington's trial BEV bus has it's batteries mounted on the roof.
Why would you do that - a large amount of weight up high, which can't be great for stability.
On the subject of Wellington Electric buses, one morning a week or so back, on the #1 route into town they had one of the new Electric double decker buses operating. Most mornings lately have been utilizing the diesel double decker buses.
A couple of my observations from the trip in on the electric double decker bus:
1) The electric double decker bus is smaller than the conventional diesel double decker buses (single rear axle instead of the two)
2) The ride felt a lot firmer than the conventional diesel bus
3) On the top deck, just in front of the stairs, there is a massive white box thing. Unsure what it is. maybe more batteries.
4) The ride felt a bit more jolting as the bus moved away from a stop. Hard to explain, but with the diesel buses as engine power and torque increase as revs rise, it's a smooth movement, but with the electric bus and instant torque from effectively 0 revs it's a jump sudden movement. This isn't down to the driver, as the route and time have had the same driver for the last few weeks.