Superchargers data accuracy?

[Scapegoat]

Hello all,

Over a month into Tesla ownership (Model Y long range) and used a 250kw Supercharger at the weekend.

The car was about 15% when plugged in and over the course of a relatively quick spot of food returned to find the car 99% full - amazingly quick (normally set the car to a max change of 80% but when I charged it at home the day before let it go to 100% because of a long road trip - and hadn’t reduced it back down).

When I ended the charge the display in the car suggested a cost of c.£35.

Having downloaded the invoice today the bill is just shy of £50 as it charged me £0.67 per kWh (up from £0.53 a few weeks back).

The invoice also suggests it put 73kwh into the car. Which is 97% of the usable battery? But it should have only put in 85%.


Some thoughts / questions:

(1) Is it normal for the car to not display the correct fee at the time?
(2) Maybe I missed it, but does it tell you the rate per kWh when you plug in? £0.67 is expensive
(3) What is the usable battery? I thought it was 75 - if it is how accurate is either the in car % charge OR the charger log ? One of them seems to be wrong.

 

[qwickshot]

You get charged for the energy delivered to the car. What gets put into the battery will be less.

Putting energy into the battery has an efficiency loss and you also need to consider thing like battery heating/cooling, cabin heating/cooling etc.

I think a lot of non tesla chargers bill you for what’s coming from the grid so you are also paying for the AC to DC conversion loss which is about another 10% before you consider all of the above.