Tesla's 85 kWh rating needs an asterisk (up to 81 kWh, with up to ~77 kWh usable)

[bjornb]

I'll keep an eye on the cell voltage diff and temp diff in the future.

From the temp data in my post above I also had a voltage screenshot:

Corresponding temp data:

I found some additional screenshots with cell voltages but no corresponding temp data from earlier this year, they had voltage diffs in the 4-9mV region.

 

[bjornb]

Temps and cell voltage diff after todays commute:

 

[apacheguy]

7 mV seems reasonable to me. Try again the next time you supercharge.

 

[wk057]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

The posts in question were moved here:

snippiness
and
snippiness

My original sentiment in my final post linked above stands. The fact that this was carved out of the thread by moderators without warning or alerting to what would need improving to retain the information simply proves how useless TMC is for technical discussion and debate.

 

[McRat]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

The posts in question were moved here:

snippiness
and
snippiness

My original sentiment in my final post linked above stands. The fact that this was carved out of the thread by moderators without warning or alerting to what would need improving to retain the information simply proves how useless TMC is for technical discussion and debate.

I have always enjoyed reading your posts. Some folk do not understand what it takes to record and report tech data. A lot of manhours.
Much of the content that appears in tech threads is not researched or supported. You are an exception which is critical to a tech board's survival in the long run.

We had a true expert on another site who would constantly be pushed into debates by those with no actual testing experience.
He did not suffer fools easily, but was not vulgar or threatening. While there were complaints against him, we kept him on because he knew his stuff and helped a lot of folk even if he wasn't applying for Friendliest Poster of the Year.

Keep up the good work.

 

[supratachophobia]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

The posts in question were moved here:

snippiness
and
snippiness

My original sentiment in my final post linked above stands. The fact that this was carved out of the thread by moderators without warning or alerting to what would need improving to retain the information simply proves how useless TMC is for technical discussion and debate.

Pack it up everyone, we are moving to Discord....

 

[JRP3]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

I noticed that, and I used the "Report" function to voice my disagreement with the move. A little bit of attitude is not enough to justify removing useful information from the thread.

 

[wk057]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

The posts in question were moved here:

snippiness
and
snippiness

My original sentiment in my final post linked above stands. The fact that this was carved out of the thread by moderators without warning or alerting to what would need improving to retain the information simply proves how useless TMC is for technical discussion and debate.

Moderators have moved the posts back.

Thanks.

 

[JRP3]

Thank you moderators.

 

[Jkr85]

I was just made aware that TMC moderators silently removed a chunk of this thread, including a detailed response to debated points relevant to the conversation.

The posts in question were moved here:

snippiness
and
snippiness

My original sentiment in my final post linked above stands. The fact that this was carved out of the thread by moderators without warning or alerting to what would need improving to retain the information simply proves how useless TMC is for technical discussion and debate.

Dear @wk057,

Please do stick around!

Ps the posts you mentioned just as magically seem to have reappeared in the thread.

Sincerely yours,

Jkr81,757383 aka Jkr85

 

[supratachophobia]

I'll keep an eye on the cell voltage diff and temp diff in the future.

From the temp data in my post above I also had a voltage screenshot:
View attachment 266179

Corresponding temp data:
View attachment 266177

I found some additional screenshots with cell voltages but no corresponding temp data from earlier this year, they had voltage diffs in the 4-9mV region.

@bjornb - I have noticed the same high temp reading from number 17 on my end as well. Any ideas what causes this yet?

 

[trayloader]

Man. Please limit the drama. Such a genius. Unnecessary thin skined.
Please help us with Your knowledge and experience.

 

[skitch23]

I know this must be buried in this thread somewhere but I can't find it. What was the useable kWh on a classic 60 (not the software limited one)? thanks

 

[FlatSix911]

Here is the article from Electrek ... Tesla’s hacked Battery Management System exposes the real usable capacity of its battery packs

Jason Hughes, a Tesla owner and hacker tinkerer, was the first to reveal the discrepancy in Tesla’s advertised battery capacity versus the actual capacity in the pack and the available capacity. He did it through a tear down of the since discontinued 85 kWh battery pack of a Model S. He found that the 85 KWh battery pack actually only had a capacity of up to 81 kWh and ~77 kWh usable capacity. Now the data is directly from Tesla’s software and not a calculation based on the capacity of cells from a tear down of a pack. He gathered similar data from other Tesla models. Here’s a list he sent to Electrek:

• Original 60 – ~61 kWh total capacity, ~58.5 kWh usable.
• 85/P85/85D/P85D – ~81.5 kWh total capacity, ~77.5 kWh usable
• 90D/P90D – ~85.8 kWh total capacity, 81.8 kWh usable
• Original 70 – ~71.2 kWh total capacity, 68.8 kWh usable
• 75/75D – 75 kWh total capacity, 72.6 kWh usable
• Software limited 60/60D – 62.4 kWh usable
• Software limited 70/70D – 65.9 kWh usable

 

[ishareit]

Here is the article from Electrek ... Tesla’s hacked Battery Management System exposes the real usable capacity of its battery packs

Jason Hughes, a Tesla owner and hacker tinkerer, was the first to reveal the discrepancy in Tesla’s advertised battery capacity versus the actual capacity in the pack and the available capacity. He did it through a tear down of the since discontinued 85 kWh battery pack of a Model S. He found that the 85 KWh battery pack actually only had a capacity of up to 81 kWh and ~77 kWh usable capacity. Now the data is directly from Tesla’s software and not a calculation based on the capacity of cells from a tear down of a pack. He gathered similar data from other Tesla models. Here’s a list he sent to Electrek:

• Original 60 – ~61 kWh total capacity, ~58.5 kWh usable.
• 85/P85/85D/P85D – ~81.5 kWh total capacity, ~77.5 kWh usable
• 90D/P90D – ~85.8 kWh total capacity, 81.8 kWh usable
• Original 70 – ~71.2 kWh total capacity, 68.8 kWh usable
• 75/75D – 75 kWh total capacity, 72.6 kWh usable
• Software limited 60/60D – 62.4 kWh usable
• Software limited 70/70D – 65.9 kWh usable

My calculations based on the kW added, battery percentage and the ideal miles added after a battery charge on my 75 RWD MS also point to about 72 kWh usable battery capacity in my car.

 

[lymex2018]

Do you happen to know the layot of the pack and where the temperatures are measured?
Is it two temps per module (coolant temp in and out perhaps?)


This is from my car when it was charging at a SuC last February:


While driving in February:


While driving a few days ago (December):

The highest temp is always measured at position 17...

There is a video on youtube named "Tesla boat battery destruction and teardown" where you can see the two temperature sensors per module at 4:10 and afterwards.

If you leave the car in a stable environment such as an underground parking lot for over 24 hours without heating or heavy use of the battery, the temperature at all the 32 sensor points should be unified. If you then use TM-Spy or SMT to measure the temperatures and they are not the same, then those sensors are not well calibrated. You can record this and calibrated manually later. For instance, if 17th is 1.2 degree higher than the average, then subtract 1.2 from subsequent measurement should be Ok. This is my car today and this 0.7C difference seems to be small.


Have you ever recorded the temperature data by SMT when super charging?
Once I entered a SC station when SoC was low but the temperature was 40+C, and when charging at 110+kW of power, it was a real challenge for the cooling system. As can be seen from the chart, the temperature difference was not two much.


As for the pack value, mine was about 98.5kWh when fairly new (Sept 2017, no SMT) and now is 97.9kWh.
BTW, this value is best viewed when recently complete a discharge-charge cycle to let the BMS to calibrate.

 

[bjornb]

Have you ever recorded the temperature data by SMT when super charging?

No, but I will go for a longer trip next week, I will do some supercharging logging then.

I did test the csv logging in ScanMyTesla last week, logging a few hours of charging at home:

I will also check module temps when parked for 24+ hours some day.

 

[FlatSix911]

A recent Electrek article on a conversion project using some of Jason's inventory of Tesla parts

Watch the Tesla-powered Honda Accord ‘Teslonda’ launch from 0 to 60 mph in 2.7 seconds

 

[lymex2018]

I will also check module temps when parked for 24+ hours some day.

That will be interesting to see. My Canbus shut off after an hour or so when recording by SMT.

 

[sorka]

Can someone else explain better than me *why* there is no actual zero mile buffer?

Degradation or change in software?