Roadster Owner Based Study of Battery Pack Capacity Over Time

[richkae]

Hey not that I own a Tesla yet, but working on it... I just want to give a shout-out to Richkae (as well I'm sure of the parallel internal efforts of Tesla), for doing this pioneering research. It will aid Tesla, and it will aid us all in future vehicles/battery packs to be totally brainless/transparent charging efforts. The entire community benefits from those who are sharing their logs, and Richkae's ongoing volunteer work.

thx!

Thanks Greg. Bumping this thread to remind people that we always need fresh data!

[Kevin Sharpe]

Bumping this thread to remind people that we always need fresh data!

I sent my logs (VIN 272) a couple of months ago but had no response... do you normally acknowledge data submissions?

[richkae]

I sent my logs (VIN 272) a couple of months ago but had no response... do you normally acknowledge data submissions?

No, I'm horrible. I just wait for enough new data to roll in an to make it worth making some new charts.
I'll acknowledge them from now on.

[Kevin Sharpe]

I'll acknowledge them from now on.

glad it's not going into a black hole have lots more logs to send you and will encourage the brits to support your study

[hcsharp]

...
If you send the raw files, then when improvements are made to the parser, I can re-run the files without asking you to resend the data.
...

I just want to confirm that you would prefer getting the raw files. Correct?

I'm also wondering if you even want my data. More than a year old but only about 12K miles. Range mode charge gets about 246 mi. So if you're looking to study battery degradation, I don't really have any.

I'd like to suggest the possibility that capacity loss may not be related to miles so much as average level of discharge for each charging cycle. It's likely that those who drive a lot will generally be at a lower SOC when they plug in every night. Perhaps you have enough data to compare somebody who, say, drives a lot but charges at work and at home so that they rarely reach a low SOC before charging, to somebody with the same miles but only charges once a day. Maybe you can plot average level of discharge against capacity loss per mile.

[richkae]

I just want to confirm that you would prefer getting the raw files. Correct?

I'm also wondering if you even want my data. More than a year old but only about 12K miles. Range mode charge gets about 246 mi. So if you're looking to study battery degradation, I don't really have any.

I'd like to suggest the possibility that capacity loss may not be related to miles so much as average level of discharge for each charging cycle. It's likely that those who drive a lot will generally be at a lower SOC when they plug in every night. Perhaps you have enough data to compare somebody who, say, drives a lot but charges at work and at home so that they rarely reach a low SOC before charging, to somebody with the same miles but only charges once a day. Maybe you can plot average level of discharge against capacity loss per mile.

Raw files are best.
In order to be able to compare things like depth of discharge you need more than just the last raw log file, you need a whole series of log files over the life of the car.
The raw files contain high detail records for a couple of months of data, and low detail records for many years. In order to guarantee that you have high detail for the entire life of the car you have to pull a log file every month or two.
I haven't even done that for my own car ( I've missed a few months ) but I'll try to make a chart.

[jory]

Raw files are best.
In order to be able to compare things like depth of discharge you need more than just the last raw log file, you need a whole series of log files over the life of the car.
The raw files contain high detail records for a couple of months of data, and low detail records for many years. In order to guarantee that you have high detail for the entire life of the car you have to pull a log file every month or two.
I haven't even done that for my own car ( I've missed a few months ) but I'll try to make a chart.

what do you mean by "raw files"?

i've been sending files sent through the VMSParser with the -b flag. do you mean that output or something else?

thanks.

[strider]

what do you mean by "raw files"?

i've been sending files sent through the VMSParser with the -b flag. do you mean that output or something else?

thanks.

If you're ok w/ sending GPS data on where you've charged, it would be most beneficial to send the "raw" (before it's run through the parser) file. That way if upgrades are made to the parser or other data is desired they can re-run your data automatically.

Personally, I'm only sending in my VMSParser output but I'm keeping all the raw files so if need be I can re-run w/ a new version of the parser or different options. So that's an option as well.

[richkae]

If you're ok w/ sending GPS data on where you've charged, it would be most beneficial to send the "raw" (before it's run through the parser) file. That way if upgrades are made to the parser or other data is desired they can re-run your data automatically.

Personally, I'm only sending in my VMSParser output but I'm keeping all the raw files so if need be I can re-run w/ a new version of the parser or different options. So that's an option as well.

The output from the VMSParser provides time your battery has spent at state of charge, charge rate and temperature. It also provides a summary of daily driving distances, the firmware history, and how long each 1000 miles of odometer took. Lastly it provides the battery self reported capacity history.

I was originally hoping to see if any of those factors affected battery capacity, but so far we just don't have enough data. The charge rate and temperature data only comes from the "short term" section of the log - and the log only keeps about 2-3 months of that data - so if you don't keep a complete history of log files ( by gathering and saving one every 2-3 months ) then that data isn't very meaningful.

If we collectively discover some factor that seems important, we can go back and add processing that data to the parser and re-run all the log files. If you stay interested in the results of this thread, then its best if you do that.

The really young cars have not been very interesting so far.
There should be a lot of 3 year old cars out there now - and over the next few months a lot more cars will be providing very interesting data.

[Doug_G]

I download my logs periodically, and I believe I have a complete record of my car's activity. If you think that might be helpful I can make the full set available.