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Depends what car you want to fully charge. A fully charged LEAF holds 22kWh (usable) I belive from empty to flat. So 22 x 15.45p = £3.40

Edit: TCR includes your daily tariff standing charge so your actual kWh unit price will be slightly less.
 

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TCR includes a proportion of the standing charge across a standard usage pattern. Up to you whether you put in that price, or pull the lower, clean kWh rate off your bill and use a "marginal" comparison.
 

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You'd pay the standing charge even if you didn't have an EV, so I'd be inclined to go with the per kWh figure rather than the TCR.
 

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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?
 

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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?
Volts x amps = watts . so the amps change with different voltage but not the kwh in the pack (power).
To charge the pack from 240v mains will use the same kwh (although with a slight overhead for ac> dc conversion and management system)
 

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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
 

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Yes I understand that but if you've got to step up the voltage you've need more current in for less power out so the kWh on the domestic side should be greater (ignoring any efficiency losses from the charger)

I'll have a look into this later but my theory comes from working with inverters surly your trying to get something out of nothing trying to get [email protected] input to equal [email protected]
 

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Sorry, you're still misunderstanding.
I think you're mixing kW with kWh. One is energy, one is power.

For example, the LEAF battery is 24kWh which powers a 80kW motor.
 

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Yes I'm going to have to sit in a corner with a piece of paper and get it straight in my head.

I'm still struggling, as I see it 24kwh is the same as supplying 24,000w for an hour now that would take less current to supply at a higher voltage. So how can you see 24/22 KWh on your domestic meter at 240v when your stepping up the voltage to 360v??? I think I'm confusing myself now :)
 

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I have never got more than 19kWh in my LEAF (I have a kWh meter next to my charger). Also the TCR rate is higher than you actually pay. My per kWh fixed rate is 10.46p per kWh.
 
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Yes I'm going to have to sit in a corner with a piece of paper and get it straight in my head.

I'm still struggling, as I see it 24kwh is the same as supplying 24,000w for an hour now that would take less current to supply at a higher voltage. So how can you see 24/22 KWh on your domestic meter at 240v when your stepping up the voltage to 360v??? I think I'm confusing myself now :)
I'll try to use your example above...
So we want to supply 24kWh over 240V and 360V
Firstly we need to know over how long, so lets pick 2 hours to keep it simple.
This means a power of 12kW.
As @MK Tom says: Volts x amps = watts
For 240V: 240 x Amps = 12000. So Amps = 12000/240 = 50A
For 360V: 360 x Amps = 12000. So Amps = 12000/360 = 33.333A

So the only thing that changes is the Amps.
The power is the same. The energy is the same.
 
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