90 kWh owners: Temp log a supercharge session

[apacheguy]

Would be great if someone with a 90 pack (X or S) can share a battery temperature profile of a supercharge session (preferably one where you start out without much SOC).

Basically, you should try to replicate this graph:

Here is a 12-98.5% Supercharge w/ temps for a p85 with a B battery w/ 26k mi (march '16, fw7.1, 46~48F ambient temp)
View attachment 198333

Reason for the interest is that the cells used in the 90 kWh packs apparently don't generate as much heat during charging and therefore can withstand a more relaxed taper curve.

 

[gabeincal]

Would be great if someone with a 90 pack (X or S) can share a battery temperature profile of a supercharge session (preferably one where you start out without much SOC).

Basically, you should try to replicate this graph:



Reason for the interest is that the cells used in the 90 kWh packs apparently don't generate as much heat during charging and therefore can withstand a more relaxed taper curve.

Perhaps silly question but how does one access the temperature data to graph it?

 

[David99]

Perhaps silly question but how does one access the temperature data to graph it?

The CAN bus has everything available.

 

[Electroman]

Perhaps silly question but how does one access the temperature data to graph it?

Yes very silly question. Everyone including my 90 year old grandma knows you do it through CAN bus. You know the Greyhound competitor. Didn't they teach that in kindergarten?

 

[gabeincal]

The CAN bus has everything available.

I appreciate that the car knows about it via CAN traffic. How do I know about it..?

 

[David99]

I appreciate that the car knows about it via CAN traffic. How do I know about it..?

The data is available but it's not in clear text and Tesla doesn't give documentation. Some clever people captured the data and tried to make sense out of it and some have gotten most of it decoded. I'm not aware of a user friendly software that let's normal people like us see and data. Maybe there is one that I don't know about.

 

[emir-t]

Would have a better chance of someone actually doing this if you provided a basic how to on accessing CANbus data.

How does one make cells so that they don't get heated as much? Dropping internal resistance? That would explain the less voltage sag at peak accelaration too, hence higher C rates all the way up to 1600 Amps with P90D (~6.55C) vs P85+ 1300Amps (5.65C) But why wait a while to increase the supercharge rate? As you might recall initially the 90 packs supercharged slower than 85. So they weren't exactly sure about it initially.

 

[apacheguy]

@emir-t You are indeed correct. The 90 kWh used to charge slightly slower than the 85s so the firmware engineers were treading carefully. I do find that odd though and would appreciate further clarification if anyone is privy to the details.

Here is a relatively user friendly CAN logger:

Using a Raspberry Pi 3 to interface with powertrain bus CAN3

It is more robust than TM-Spy however the latter is dead simple as you simply plug in an adapter to the diagnostic port and the rest takes place on your iPhone.

 

[gabeincal]

Requested access to beta version of TM-Spy. Then I'll get the right OBD adapter etc and will be able to report back...