How many kWh are realistically available?

[Boatguy]

A discussion with Andrew Reeves the Service Manager at Manchester Tesla (UK) revealed a Tesla document describing the causes of the discrepancy. Six points were listed, primarily the bulk of the missing kW/Hrs were at the bottom end, and yes I think 'zero mile protection' is an adequate description. This reserve being such that you can always make zero miles, even when the calculation of battery capacity has been over optimistic. Also emphasis was placed on the fact that the energy recorder only records motive power and not the auxiliary drains. Finally there was the suggestion that battery capacity was measured under laboratory conditions and therefore not real world capacity.

Other points which came from the discussion is that Supercharging does degrade battery capacity compared to normal slow charging and that it is charging to 100% which forces a more accurate calculation of battery capacity.

Boatguy, thanks for your contribution yet again. You provided useful information to me, when we had the same discussion earlier in the year when I was even more concerned about battery capacity.

You're welcome, it's my obsession with cranking numbers!

Your Service Manager feedback regarding the 100% charge forcing a recalibration also supports what @msnowh has been saying.

 

[Boatguy]

Correction, @msnow .

 

[Redaxis]

As I pulled in to a SC it hit 0% from a 100% Charge.

For me this was disappointing as almost 20% down from rated capacity

Realistically I would have expected to see 78-82kWh

This is a one time only experiment. This was done over 2 days, so there would be a small amount of vampire drain, aircon was on as was Spotify. P90D

This is not a distance problem as I know driving more economically will increase range, it was a test to see how much capacity would be available.

 

[Redaxis]

This is Tesla response after calling and speaking to a really helpful guy in service, with-in 20 mins he had emailed me and called me straight back.

This is a copy of there email explanation..


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I will give you a call back soon but I can assure you after speaking to the head technician in the workshop the figures you are giving me are right.


Below are a few links that you will fine really useful.


Also the KW’S used since last charge will only tell you what your right foot does and not what the car consumes to keep all the systems functioning.


It is pointed out below but when we talk about consumers I would mean.

-12 volt battery

-Air con, fan system.

-Coolant pump running to keep battery’s cool.

-City traffic.

-Road conditions

-Driving style.

-And a lot more.

 

[ArtInCT]

RED axis:
When you pulled in with 0 remaining, how many KW's had you consumed using the traction pack as propulsion?
I have always wondered how many KW my P90D thinks are in the traction pack.
I have yet to bring my pack to 0% or 0 miles.
Cluck Cluck... call me a chicken.

Also, they missed a "consumer". the fan system in the automatic ventilation. Mine has been seen to turn on all by itself in these really hot days when the car is in the sun. It vents the cabin (not air conditioning) to maintain a reasonable temperature inside. I suspect to defend the computers and screens from over heating. It will not do this if your traction battery is less than 20% according to the owners manual.

 

[Boatguy]

Also, they missed a "consumer". the fan system in the automatic ventilation. Mine has been seen to turn on all by itself in these really hot days when the car is in the sun. It vents the cabin (not air conditioning) to maintain a reasonable temperature inside. I suspect to defend the computers and screens from over heating. It will not do this if your traction battery is less than 20% according to the owners manual.

That explains the high vampire loss I've seen when my car is parked in the sun, with HVAC off.