Ok this is something I've wondered for a while now so here goes. I know the useable capacity of the pack is 22kwh but isn't that at 360v? So the actual power in would have to be greater to account for supply voltage being 230v? I assume the charger in the car steps the voltage up or does it split the pack and charge it at lower voltages?

This is a really common misconception and not immediately intuitive.

Power is energy over time.

A lot of the confusion comes from using a power unit (Watts) in an energy unit (kWh).

kWh is an energy unit as it's power over a period of time (one hour).

Really it should be measured in Joules but kWh makes a lot of the calculations simpler.

For a bit more detail, let's break it down what a kWh is:

kilo Watt hours

1000 Watts for one hour

1 Watt is one Joule per second

So 1 kWh is 3.6 MJ (3.6 million Joules)

Lots of definitions of a Joule on Wikipedia but a good real world example:

"the kinetic energy of a 50 kg human moving very slowly (0.2 m/s or 0.72 km/h)."

So with an EV you're converting the energy in the battery to kinetic energy which makes the car move.

The voltage is just part of the details of the energy conversion (more equations!).

Random fact: James Prescott Joule is buried just near where I live.

http://en.wikipedia.org/wiki/James_...ewer/File:James_Prescott_Joule_gravestone.JPG