Chassis CAN Logging To ASCII Text Plus Graphing

[kennybobby]

The charts are from Lola's dropbox data. At the end of SC they were only spread ~10 mV and overnight they got even closer to within 2-3 mV. It looks like the cells are in great shape.

The brick balancing current is only about 100mA max thru the bleed resistor circuit, so the cells can't really do any balancing while being charged. Even just 5A charging is trying to put 67mA into each cell of a brick. With a 100mA bleed that leaves 4.9A into the brick or 66mA into each cell. So to try to balance while charging is just not effective, and not likely done. Maybe some CAN buss decoding can answer this for sure.

 

[ArtInCT]

I cannot wait to see Kennybobby's graphs. The cell groups look very repetitive, I really wonder how the cell numbers are physically assigned to the enclosure?
Do enclosures present all the power from all their cell groups at the same time or are they modulated somehow?

Well I post this and then KennyBobby is just ahead of me GREAT JOB! Wow the proof of the self leveling is clearly there.... Thanks!

Hum... cell groups 55 thru 66 are consistently lower than the rest other than perhaps 80? Why? Is this going to be a consistant signature of this particular pack?
Or will those lower groups Round Robin with variability?

 

[jpet]

Hum... cell groups 55 thru 66 are consistently lower than the rest other than perhaps 80? Why? Is this going to be a consistant signature of this particular pack?
Or will those lower groups Round Robin with variability?

My guess is that they will get back in line after a couple of range charges / balancing operations. It's going to be interesting to take regular snapshots of the battery to see if it are indeed always the same groups of cells that get out of balance. I received my CAN logger today but have been without my car for 42 days now after I got rear ended. It should be ready by the end of the week but I heard this story last week as well... Hope to be able to start analyzing next weekend.

 

[smac]

My guess is that they will get back in line after a couple of range charges / balancing operations. It's going to be interesting to take regular snapshots of the battery to see if it are indeed always the same groups of cells that get out of balance. I received my CAN logger today but have been without my car for 42 days now after I got rear ended. It should be ready by the end of the week but I heard this story last week as well... Hope to be able to start analyzing next weekend.

Mine arrived this morning too, they must have been on the same boat

You may need drivers, and I had a warning the device's firmware needs updating (I haven't done mine yet), but it seemed to work well enough for a quick 0-60, and I'm just getting my head round using SavvyCAN properly.

Feel free to PM me if you need any help getting set up.

 

[LetsGoFast]

Great chart and fascinating data!

 

[Andyw2100]

I just want to put in a request to any of you who may be beginning to log your own CAN data. If you are willing, it would be great if you also logged a comparison run using TeslaLog, so those of us that don't have access to CAN logging might be able to get an idea of how similar or dissimilar that information is from the information you're able to obtain from the CAN bus.

You can enable TeslaLog just for a run or two if you like. The thread on it is here, and for now it is still free:

TeslaLog.com - Your hosted Tesla Data Logger - Announcement / Support threads

Below is a sample of the kind of data it can produce, from a launch I did a few weeks ago in my P85D (cold, with snow tires on, at about 85% SOC.)

Thanks!

 

[lolachampcar]

I've been curious about exactly what Launch Mode does and wanted to verify Fiks' work (where he showed it did nothing for times).

The following are a bunch of back to back 0-60 runs with battery heat enabled using both Launch Mode and Fast Foot Mode I found it interesting that the power at first wheel movement for some of the runs was near double for the Fast Foot method.

Here is a quick summary-
SoC 072.6 BatT 36.74 BatOdo 015487 same as run below as data ran together
1329.26 Launch Mode
1325.40
3.86

SoC 072.6 BatT 36.74 BatOdo 015487
1342.38 Fast Foot Mode
1338.99
3.39

SoC 072.0 BatT 37.96 BatOdo 015487
1381.37 Fast Foot Mode
1377.94
3.44

SoC 071.6 BatT 38.76 BatOdo 015487
1422.93 Launch Mode
1419.41
3.52

SoC 071.3 BatT 39.42 BatOdo 015487
1459.88 Fast Foot Mode
1456.75
plus .44 seconds for having to lift early (from other data sets)
3.57

SoC 070.9 BatT 40.21 BatOdo 015487
1487.47 Fast Foot Mode
1483.88
3.59

SoC 070.5 BatT 41.01 BatOdo 015488
1521.12 Launch Mode
1516.61
4.51 Suspect motor was getting hot

Supporting Data
Time TPS Speed R_Tq F_Tq BatV BatI Pwr
1325.36 100.0 +000.00 +338.5 +174.0 366.33 -0108.0 039.5
1325.37 100.0 +000.00 +338.9 +173.1 365.95 -0109.0 039.8
1325.38 100.0 +000.00 +345.3 +172.4 365.70 -0109.7 040.1
1325.39 100.0 +000.00 +349.2 +172.0 366.07 -0109.1 039.9
1325.40 100.0 +000.20 +349.9 +171.8 366.21 -0107.2 039.2
1325.41 100.0 +000.40 +349.2 +165.7 365.95 -0106.3 038.9
1329.24 100.0 +059.85 +199.3 +113.2 288.41 -1304.1 376.1
1329.25 100.0 +059.95 +199.1 +113.2 287.03 -1308.1 375.4
1329.26 100.0 +060.05 +199.6 +113.0 286.14 -1302.7 372.7
1329.27 100.0 +060.15 +199.3 +112.8 288.65 -1298.6 374.8
SoC 072.6 BatT 36.74 BatOdo 015487 same as run below as
data ran together
1329.26 Launch Mode
1325.40
3.86




1338.97 100.0 +000.00 +385.0 +232.3 356.76 -0228.6 081.5
1338.98 100.0 +000.00 +395.8 +235.2 356.39 -0236.2 084.1
1338.99 100.0 +000.25 +405.2 +235.0 355.49 -0242.4 086.1
1339.00 100.0 +000.60 +415.0 +235.2 355.23 -0249.9 088.7
1339.01 100.0 +000.90 +423.7 +235.6 354.48 -0264.3 093.6
1339.02 100.0 +001.20 +429.6 +235.6 353.47 -0278.0 098.2
1342.35 100.0 +059.65 +198.9 +112.2 287.90 -1290.9 371.6
1342.36 100.0 +059.75 +197.8 +112.1 287.52 -1293.8 371.9
1342.37 100.0 +059.90 +198.0 +112.1 286.02 -1294.4 370.2
1342.38 100.0 +060.00 +197.8 +112.2 287.16 -1293.1 371.3
1342.39 100.0 +060.10 +199.1 +112.2 287.28 -1301.5 373.8
1342.40 100.0 +060.20 +199.8 +112.4 286.40 -1295.3 370.9
1342.41 100.0 +060.30 +199.8 +112.4 286.64 -1287.4 369.0
1342.42 100.0 +060.40 +199.3 +112.2 287.64 -1290.7 371.2
1342.43 100.0 +060.50 +199.1 +112.1 286.77 -1278.6 366.6
SoC 072.6 BatT 36.74 BatOdo 015487
1342.38 Fast Foot Mode
1338.99
3.39




1377.92 100.0 +000.00 +368.2 +205.4 357.65 -0221.0 079.0
1377.93 100.0 +000.00 +383.9 +212.6 356.89 -0232.4 082.9
1377.94 100.0 +000.30 +396.8 +217.5 356.27 -0242.7 086.4
1377.95 100.0 +000.60 +409.1 +220.5 355.64 -0254.2 090.4
1377.96 100.0 +000.90 +421.3 +222.9 355.15 -0265.4 094.2
1377.97 100.0 +001.20 +430.5 +225.1 354.78 -0276.6 098.1
1381.34 100.0 +059.75 +172.5 +149.7 291.56 -1243.2 362.4
1381.35 100.0 +059.85 +171.4 +149.5 291.44 -1237.7 360.7
1381.36 100.0 +059.95 +171.1 +148.9 290.80 -1243.0 361.4
1381.37 100.0 +060.05 +170.3 +148.4 291.32 -1233.8 359.4
1381.38 100.0 +060.15 +170.3 +148.4 291.69 -1238.2 361.1
1381.39 100.0 +060.25 +170.1 +148.6 291.55 -1233.6 359.6
SoC 072.0 BatT 37.96 BatOdo 015487
1381.37 Fast Foot Mode
1377.94
3.44




1419.37 100.0 +000.00 +397.9 +225.3 359.11 -0183.0 065.7
1419.38 100.0 +000.00 +401.9 +229.9 359.36 -0177.3 063.7
1419.39 100.0 +000.00 +406.2 +232.1 358.75 -0183.4 065.7
1419.40 100.0 +000.00 +411.0 +231.0 357.99 -0197.8 070.8
1419.41 100.0 +000.25 +415.9 +230.1 356.86 -0216.8 077.3
1419.42 100.0 +000.45 +419.8 +231.4 355.85 -0239.8 085.3
1419.43 100.0 +000.70 +418.9 +232.5 355.48 -0252.0 089.5
1419.44 100.0 +000.90 +411.1 +231.2 355.63 -0247.2 087.9
1419.45 100.0 +001.15 +406.3 +227.3 355.63 -0243.2 086.4
1419.46 100.0 +001.35 +405.2 +225.3 355.51 -0245.4 087.2
1422.89 100.0 +059.65 +194.7 +103.9 293.58 -1203.4 353.2
1422.90 100.0 +059.75 +193.6 +103.9 294.59 -1193.9 351.7
1422.91 100.0 +059.85 +193.2 +103.9 295.84 -1193.5 353.0
1422.92 100.0 +059.95 +193.9 +103.8 295.08 -1189.4 350.9
1422.93 100.0 +060.05 +193.9 +103.4 294.95 -1188.1 350.4
1422.94 100.0 +060.15 +193.2 +103.4 295.09 -1185.6 349.8
1422.95 100.0 +060.25 +192.5 +103.0 294.44 -1190.7 350.5
1422.96 100.0 +060.35 +191.7 +102.8 294.32 -1185.8 349.0
SoC 071.6 BatT 38.76 BatOdo 015487
1422.93 Launch Mode
1419.41
3.52






1456.73 100.0 +000.00 +145.4 +131.2 363.32 -0106.8 038.8
1456.74 100.0 +000.00 +173.8 +143.8 361.56 -0133.5 048.2
1456.75 100.0 +000.15 +226.6 +162.2 360.57 -0160.2 057.7
1456.76 100.0 +000.30 +271.7 +180.7 359.92 -0177.6 063.9
1456.77 100.0 +000.40 +299.6 +195.2 359.30 -0187.7 067.4
1456.78 100.0 +000.55 +317.1 +206.5 358.67 -0199.4 071.5
1459.82 100.0 +054.25 +189.9 +144.5 297.59 -1167.9 347.5
1459.83 100.0 +054.35 +189.1 +144.5 297.71 -1165.6 347.0
1459.84 100.0 +054.45 +188.8 +144.5 297.72 -1165.4 346.9
1459.85 099.6 +054.55 +188.4 +144.7 297.61 -1168.5 347.7
1459.86 093.2 +054.65 +188.0 +144.9 297.60 -1165.8 346.9
1459.87 086.4 +054.80 +187.1 +145.1 297.23 -1173.7 348.8
1459.88 080.4 +054.90 +186.9 +145.1 297.47 -1169.0 347.7
SoC 071.3 BatT 39.42 BatOdo 015487
1459.88 Fast Foot Mode
1456.75
plus .44 seconds for having to lift early (from other data sets)
3.57


1483.85 100.0 +000.00 +343.3 +222.1 356.80 -0225.7 080.5
1483.86 100.0 +000.00 +362.3 +228.8 356.17 -0236.1 084.0
1483.87 100.0 +000.00 +377.4 +232.8 355.79 -0244.0 086.8
1483.88 100.0 +000.25 +392.9 +233.2 354.92 -0256.1 090.8
1483.90 100.0 +000.90 +407.3 +235.6 354.27 -0268.5 095.1
1483.91 100.0 +001.20 +419.3 +235.8 353.88 -0276.9 097.9
1483.92 100.0 +001.40 +428.1 +234.1 353.38 -0285.2 100.7
1483.93 100.0 +001.65 +433.8 +232.8 353.00 -0294.0 103.7
1483.94 100.0 +001.85 +437.9 +230.3 352.87 -0297.1 104.8
1487.41 100.0 +059.50 +164.8 +140.1 300.26 -1115.6 334.9
1487.42 100.0 +059.60 +164.4 +140.1 300.38 -1117.6 335.7
1487.43 100.0 +059.70 +163.7 +140.1 300.26 -1118.2 335.7
1487.44 100.0 +059.80 +163.0 +140.3 300.38 -1116.7 335.4
1487.46 100.0 +060.00 +162.8 +140.5 299.38 -1121.2 335.6
1487.47 100.0 +060.05 +162.2 +140.6 300.37 -1117.8 335.7
1487.48 100.0 +060.15 +161.7 +140.6 299.60 -1122.3 336.2
1487.49 100.0 +060.25 +161.1 +140.6 300.99 -1115.5 335.7
1487.50 100.0 +060.35 +161.1 +140.8 299.48 -1122.0 336.0
1487.51 100.0 +060.45 +160.4 +140.6 300.75 -1115.1 335.3
SoC 070.9 BatT 40.21 BatOdo 015487
1487.47 Fast Foot Mode
1483.88
3.59


1516.57 100.0 +000.00 +362.1 +172.2 362.80 -0117.0 042.4
1516.58 100.0 +000.00 +363.2 +170.9 362.93 -0114.7 041.6
1516.59 100.0 +000.00 +364.7 +170.3 362.53 -0114.1 041.3
1516.60 100.0 +000.00 +365.2 +169.6 362.67 -0114.5 041.5
1516.61 100.0 +000.20 +363.4 +170.3 362.54 -0116.2 042.1
1516.62 100.0 +000.40 +350.8 +169.6 362.43 -0118.1 042.8
1516.63 100.0 +000.50 +343.8 +168.9 362.55 -0118.5 042.9
1516.64 100.0 +000.65 +349.2 +170.1 362.68 -0118.7 043.0
1516.65 100.0 +000.75 +347.0 +173.1 362.68 -0118.0 042.7
1516.66 100.0 +000.85 +354.3 +174.2 362.54 -0117.9 042.7
1516.67 100.0 +000.90 +350.3 +170.9 362.56 -0118.6 042.9
1516.68 100.0 +000.95 +354.9 +169.8 362.79 -0119.3 043.2
1516.69 100.0 +001.00 +353.4 +171.6 362.43 -0118.1 042.8
1516.70 100.0 +001.05 +358.8 +173.1 362.67 -0115.7 041.9
1516.71 100.0 +001.10 +357.9 +173.5 362.67 -0114.8 041.6
1521.07 100.0 +059.55 +185.6 +095.6 303.10 -1071.9 324.8
1521.08 100.0 +059.60 +185.3 +095.6 302.98 -1068.7 323.7
1521.09 100.0 +059.70 +184.2 +095.6 303.98 -1075.7 326.9
1521.10 100.0 +059.80 +184.0 +095.6 303.22 -1072.6 325.2
1521.11 100.0 +059.90 +183.2 +095.5 303.47 -1074.0 325.9
1521.12 100.0 +060.00 +182.5 +095.3 303.10 -1073.4 325.3
1521.13 100.0 +060.10 +182.3 +095.1 302.23 -1074.7 324.8
1521.14 100.0 +060.15 +181.2 +095.1 303.23 -1073.9 325.6
1521.15 100.0 +060.25 +181.0 +094.9 303.23 -1072.1 325.0
1521.16 100.0 +060.35 +181.2 +094.7 303.61 -1078.0 327.2
1521.17 100.0 +060.45 +181.0 +094.7 303.60 -1070.6 325.0
1521.18 100.0 +060.55 +180.8 +094.7 303.36 -1079.2 327.3
1521.19 100.0 +060.65 +181.0 +094.7 302.72 -1071.0 324.2
1521.20 100.0 +060.70 +181.2 +094.5 303.73 -1068.6 324.5
SoC 070.5 BatT 41.01 BatOdo 015488
1521.12 Launch Mode
1516.61
4.51 Suspect motor was getting hot

Raw Data
Dropbox - Multiple0_60RawData.TXT

 

[kennybobby]

Here is an animation of the Champ's supercharging session from the dropbox dataset. steps are about 150 seconds and total time charging was about 4000.

 

[jpet]

It is so great to clearly see in the animation that the cells only started balancing at the very end (above 4.15V). This is as expected of course but I love seeing it happening this way. One can imagine that never doing a range charge leaves the battery in a not so great shape after a while.

 

[Andyw2100]

Here is an animation of the Champ's supercharging session from the dropbox dataset. steps are about 150 seconds and total time charging was about 4000.

It is so great to clearly see in the animation that the cells only started balancing at the very end (above 4.15V). This is as expected of course but I love seeing it happening this way. One can imagine that never doing a range charge leaves the battery in a not so great shape after a while.

That graphical representation and animation is awesome!

As jpet points out, it really shows very clearly when the pack balancing takes place. I know that it has long been common knowledge that the pack balances itself at the end of a range charge. But unless I'm mistaken, this was something that sophisticated owners like you guys figured out, right? Tesla never came out and said, "This is when the pack balances itself."

Assuming the above is correct, wouldn't that have been a helpful piece of information for all owners to have? It doesn't seem like there is anything particularly proprietary about it. And while I understand that Tesla doesn't want owners to have to think about or worry about battery management, adding the suggestion to do a range charge at least a couple of times a year would not be a complicated addition to what they already tell us about battery care. Why not be more transparent?

 

[jpet]

I guess for most owners this is a quite natural process. Almost everybody does range charges at least a couple of times a year, e.g. when you go on a long trip. Only a few nerds like me want to dive into the nitty gritty of how these packs really work in an attempt to get as many cycles out of them as possible. I understand explaining all of the technical details could potentially hamper the adoption of EVs. If you really want to know about these things, the data is available.

As far as I know, Tesla has indeed never communicated about the concept of "balancing" a battery pack and the fact that it is triggered at around 93% SOC. I assume it is triggered at around the point charging at CC changes into charging at CV but I'm not sure. That's something I'd like to validate with my logger. I have a large list of things I want to analyze...

Here's the graph indicating the point where CC changes into CV for a Panasonic NCR18650A cell:

 

[lolachampcar]

Anyone want to take a stab at expanded graphical analysis of current, front and rear torque for the wet 0-60 runs? I'd love to get a feel for the time constant on Telsa's traction control.

 

[apacheguy]

It is so great to clearly see in the animation that the cells only started balancing at the very end (above 4.15V). This is as expected of course but I love seeing it happening this way. One can imagine that never doing a range charge leaves the battery in a not so great shape after a while.

I do realize that the pack top balances, but I still don't understand what prevents it from doing this at any SOC. The BMS has the data it needs to know which groups are off balance.

 

[kennybobby]

Here's a start on the wet 0-60 run time history chart. Current is on the secondary axis at the right. Time axis is in seconds.

You can really see how the traction control pulled the current back and left a big dip in the torque curve of both motors.

 

[kennybobby]

The first 2 seconds expanded to see the fluctuations in the current. Pack voltage sags hard under 1300A draw...

 

[LuckyLuke]

Great info here, thank you for this insight.
I can recall that some Tesla rep's have been commenting about balancing procedure as "charge to full, and let it sit for a while". That last part appears to be the key in achieving a well balanced pack.
Some questions arise: Like how much time is "a while", since the balancing bleeds at 100mA only?
What is the typical voltage imbalance range like? Something like lola's 10mV? How long would it take to bleed such a typical imbalance?

Also you don't really want the pack to sit at 100% for too long, so here is my theory: If someone would like to balance his pack, would it be best to set charge at say 95% (instead of 100%) and let it sit for x hours? (x to be determined, see questions above)

 

[lolachampcar]

kb,
That must have been one of the slightly sideways runs. It is amazing just how much power this car can put down in very slippery conditions.

It looks like Tesla is using the lower grip front wheels to feel there way around. Those torque fluctuations are either an attempt to determine absolute available grip or the car is pulling front torque on steering correction. An interesting exercise would be to log steered angle as well but that is for another day.

Neat stuff. Thank you.

 

[ArtInCT]

Here is an animation of the Champ's supercharging session from the dropbox dataset. steps are about 150 seconds and total time charging was about 4000.

Kenny bobby:

Man, you are the BEST! Great work on that animation of the CAN bus recharge... Love it.

Lola: at about 157.8 what do you think was the cause for the R tq ft lbs to diminish so rapidly? A chirp and spin and then give up? A traction limitation??

 

[lolachampcar]

Ten Tesla diag cables arrived last night. Time to build up some loggers.

 

[scaesare]

I guess for most owners this is a quite natural process. Almost everybody does range charges at least a couple of times a year, e.g. when you go on a long trip. Only a few nerds like me want to dive into the nitty gritty of how these packs really work in an attempt to get as many cycles out of them as possible. I understand explaining all of the technical details could potentially hamper the adoption of EVs. If you really want to know about these things, the data is available.

As far as I know, Tesla has indeed never communicated about the concept of "balancing" a battery pack and the fact that it is triggered at around 93% SOC. I assume it is triggered at around the point charging at CC changes into charging at CV but I'm not sure. That's something I'd like to validate with my logger. I have a large list of things I want to analyze...

Here's the graph indicating the point where CC changes into CV for a Panasonic NCR18650A cell:

View attachment 110391

Data seems to indicate that 4.2V is near 100% on the Tesla (with some indications that 100% may only be ~4.15V), which would mean that balancing @ 93% would be at a voltage less than Panasonic's spec.

I too wonder where Tesla's CC-CV transition is...