Roadster Owner Based Study of Battery Pack Capacity Over Time

[richkae]

Just sent in my data for 2.0 sport @ 18k miles.
I've been using the Tesla Tattler for several months with the cooldown feature, which should show the battery spends more time at a lower temperature, but also at a lower state of charge. It will be interesting to see how this compares with the other logs.

I will look into whether the existing parser will allow you to generate histograms from specific time ranges.
Then you can run it and generate histograms from before and after the Tattler. It will be interesting to compare temperatures.
If the code does not currently support it, I will update it and add it.
I should probably also include the ambient temperature in the data otherwise those comparisons are less meaningful.

It would have been much easier to just ask everyone to send in all their log files at a regular basis - that way I could add variables that become interesting.
But this way you know exactly what data is being sent, and don't have to have apprehension about sending GPS data or other unknowns.

 

[cinergi]

Would you be willing to send your log files so I can debug? If you prefer, I will delete them as soon as I have fixed the problem.

I gave them to Tom last night -- PM me if you still want them and I'll send them along.

 

[Doug_G]

No GPS data is recorded in the logs. There is a separate file that includes the coordinates of where you plug in, but it is encrypted.

 

[tomsax]

I just posted a new version of my command-line-based parser that adds support for firmware versions earlier than 3.2 (prior to March, 2009), and fixes the problem that cinergi was seeing with the aggregation feature that Rich is using for his study.

VMS Log Parser for Tesla Roadster

 

[W.Petefish]

I'll send mine as soon as I pull the logs. I recently had a near miss in terms of range and almost not making it home. (8 miles left on standard charge)

 

[JoshG]

. I recently had a near miss in terms of range and almost not making it home. (8 miles left on standard charge)

If it showed 8 miles of range, that's no near-miss. Mine has twice gone into "---" miles left (happens below 8 or 9 miles of range) with a warning message on screen that the charge is so low that accurate range can no linger be determined. Last week when it happened, I actually made it ANOTHER 5 miles after that to home... So they build in a healthy buffer on their range calcs for some safety.

 

[zack]

I've seen that message right after seeing 20 miles of range left. Made it through 30 minutes of rush hour traffic and 12 miles of travel.

 

[Dragon]

Happened to me several times. You need to switch to range mode (otherwise the car will shut off, this warning will pop up with 2-3 miles in standard mode left) and when going below the 20 miles the car will not show any range anymore. Theoretically the car should be able to move another 20 miles, but you are at the limit and it's highly recommended to charge as soon as possible. I think I've read that there will be another warning later, but then the battery will be as good as empty and you should not continue to drive.

 

[user497]

Showing only 167 ideal miles after 1 year and a half

I just sent over my logs. The car is 1 1/2 years old and has 11k miles on it. I've only ever charged it with my 110V adapter since I only do about 20 miles per day on average. I don't think I have ever charged it range mode (maybe once a year ago). When I fully charge it in standard mode, I only get around 167 miles which seems very low. I've talked to Tesla about this several times and they have said that the battery is actually fine but the firmware is showing a lower number than expected because it is not properly calibrated and because I rarely charge it completely or from near empty. Hopefully you can confirm what Tesla is saying.

 

[dhrivnak]

If that is 167 standard miles that could be normal. If that is 167 ideal miles I would be concerned. While I normally show 179 ideal miles I will frequently show only 150 STD miles with all the hills here.

 

[user497]

If that is 167 ideal miles I would be concerned.

It is ideal miles. My standard miles (on the odometer by the steering wheel) is usually 20-30 miles less but I don't really look at that very often so I could be a little off there.

 

[Alan]

I just sent over my logs. The car is 1 1/2 years old and has 11k miles on it. I've only ever charged it with my 110V adapter since I only do about 20 miles per day on average. I don't think I have ever charged it range mode (maybe once a year ago). When I fully charge it in standard mode, I only get around 167 miles which seems very low. I've talked to Tesla about this several times and they have said that the battery is actually fine but the firmware is showing a lower number than expected because it is not properly calibrated and because I rarely charge it completely or from near empty. Hopefully you can confirm what Tesla is saying.

What Tesla are saying makes sense, but why not try it out. Dont charge for a few days to allow the level to drop. Given your battery may not be correctly calibrated dont push it too far - perhaps down to 20 ideal miles in standard mode (50 plus in range mode). Then fully recharge in range mode and see what happens.

 

[user497]

What Tesla are saying makes sense, but why not try it out. Dont charge for a few days to allow the level to drop. Given your battery may not be correctly calibrated dont push it too far - perhaps down to 20 ideal miles in standard mode (50 plus in range mode). Then fully recharge in range mode and see what happens.

I actually did that the last time I charged. From the VMSParser this is the output:

11/26/2011 19:47:43 - 11/27/2011 22:13:50 (26:26:07) Charge 26% -> 86% 122V 15A of 15A 48.3 kWh 0.0 Ah 0.0 Ah 556 Wh/mi

It only went up to 167 on that last charge. In the past it had been slightly higher (around 169). They suggested that when I bring it in for its annual service in March that they will bleed it and then charge back up with a 440V and it should also help. They've looked at the logs and insist the battery is fine and I have no reason not to believe them but at the same time no one else seems to be reporting similar issues. I may also have a slightly different driving habit than most since I drive it every day but only put about 20 miles a day.

 

[Alan]

I guess if you went from 26% to 86% you re-charged in standard rather than range mode. There are plenty here who know more than me, but I think that unless once in a while you charge to 100% in range mode it will struggle to give an accurate state of charge.

 

[richkae]

Make sure you are retrieving a log file from your car every couple of months and archiving them.
If we make discoveries about the health of batteries the parser can be improved and used to reprocess the old data.

 

[hcsharp]

... and then charge back up with a 440V and it should also help. ...

How high is the max voltage that you can charge with? I thought it was 268. Can you really do 440?

To back up what Alan said, unless you've had a recent software update then you won't balance your cells without a full range-mode charge and then let it sit for a couple hours. Even with the new software it does more balancing with range mode than std.

 

[jory]

Step 1: Use a USB stick to download log files from your car. Try to do so at least every 3 months.

where is the USB slot and how should the USB drive be formatted? i assume a small (1GB or less) USB drive is fine? thanks.

 

[user497]

where is the USB slot and how should the USB drive be formatted? i assume a small (1GB or less) USB drive is fine? thanks.

The file is only about 12 MB so anything bigger than that should be OK. I first tried with an old 30MB thumb drive but it didn't work for me (I don't think it was a size issue) so I used the one that comes with the roadster which was a 1GB one and it worked. Note that if you are using your own drive you will need to create a directory named "VehicleLogs" in the root of your drive.

 

[jory]

The file is only about 12 MB so anything bigger than that should be OK. I first tried with an old 30MB thumb drive but it didn't work for me (I don't think it was a size issue) so I used the one that comes with the roadster which was a 1GB one and it worked. Note that if you are using your own drive you will need to create a directory named "VehicleLogs" in the root of your drive.

thanks user497, knowing the directory naming was very helpful.

for those who have never done it, i turned the car "on" with the key and found the USB port under the center console towards the front of the car. i plugged the USB drive in and a message came up on the display.

the number on the lower right incremented slowly for a minute or two then the notification went away. i pulled the key out plugged the USB drive into my mac and can see a tar archive file in a new folder (with my VIN number as the name of the new folder) in the VehicleLogs folder. the .tar archive file name itself specifies the date so it look like i could just plug the same USB stick in without having to rename anything and no old data would be overwritten.

i first tried a 1GB USB drive which had been formatted FAT16. the roadster tried to download to it but failed. i reformatted FAT32 and that worked.

 

[jory]

I just posted a new version of my command-line-based parser that adds support for firmware versions earlier than 3.2 (prior to March, 2009), and fixes the problem that cinergi was seeing with the aggregation feature that Rich is using for his study.

VMS Log Parser for Tesla Roadster

finally went to this page to get the parser and found that it contained good instructions for downloading the log data from the car. people should go here first if they are getting started and read the helpful guidance!