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Sudden loss of range and what to do now

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
Hi everyone,

On Thanksgiving Day I had the unpleasant surprise of running out of juice with my Roadster – with 25 miles of displayed remaining range and in the absence of the usual "Low battery - Power reduced" message that should warn the user in advance in such cases. I was just 5 miles away from my hotel and its ample charging capacity.

Fortunately the tow truck was relatively quick to arrive and its cost was covered by my insurance. The car started charging as soon as I connected it to one of the hotel's chargers.

Since then though, the displayed range (in normal mode) after charging has dropped from 165 to 145 miles. The battery is a remanufactured one that I got from Tesla last year.

Now wondering what to do, beyond hoping that the 3.0 upgrade becomes available again soon. I suspect there's something massively wrong with that battery, but the Tesla service center assures me all is fine (they surely don't want me to claim some warranty on that remanufactured battery, even though I'm not sure how long it is warranted – it's been maybe 1 year and 4 months).

I've read here that there's a way to read the battery cells' health on the car logs – can someone please confirm? Should I follow these instructions and try to pull the log from the car? Sorry for the dumb questions but I've never done that.

Thank you in advance for any help...
PF
 

im4uttx

Supporting Member
May 28, 2019
354
220
Spicewood, TX
Definitely go through pulling the logs and see if a specific sheet has started showing up recently.

My (total) guess is the extremely low battery level may have damaged a cell/sheet and it is no longer capable of getting full charge. It could be the reason for the sudden loss at low range.
 

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
Definitely go through pulling the logs and see if a specific sheet has started showing up recently.

I'll do my best to pull the log. Just need to find a USB key that's 4GB or smaller. :) Not easy anymore.

Once I have the log, how do I find the data on specific battery sheets?

My (total) guess is the extremely low battery level may have damaged a cell/sheet and it is no longer capable of getting full charge. It could be the reason for the sudden loss at low range.

That doesn't sound very logical to me as the car went dead before the (apparent) range reached a critical level. So something must have happened while the battery still wasn't totally empty. Or am I missing something?...
 

im4uttx

Supporting Member
May 28, 2019
354
220
Spicewood, TX
I'll do my best to pull the log. Just need to find a USB key that's 4GB or smaller. :) Not easy anymore.

Once I have the log, how do I find the data on specific battery sheets?
I have an 8GB that seems to work most of the time. I've found it fails usually when the car goes to sleep after a few minutes (if I close the door). If I leave the door open, it seems to work fine most of the time. Perhaps the size of the USB slows down the transfer.

There are a few different options, but this is from the "-p" option.
05/24/2019 18:38:03 | 1558741083 | DAY | odo = 2494.6 range soc = 82%, brick ave 156.028Ah, brick min 155.629Ah, min Ah brick 72, CAC 155.97 Ah

It shows the min brick Ah and number. If you watch that column in the history, does it change from earlier readings to current?

That doesn't sound very logical to me as the car went dead before the (apparent) range reached a critical level. So something must have happened while the battery still wasn't totally empty. Or am I missing something?...

I'm thinking the weakest cell wasn't reporting how weak it was, and when it got low, stopped the car. Perhaps the low voltage sensitivity was an issue that could not be predicted by the car, but after the episode, now there is a known issue the roadster is aware of. But I'm no expert, just a WAG...

Good luck.
 

gregd

Active Member
Dec 31, 2014
2,531
1,768
CM98
Or by running out of juice, the car just got a very credible understanding of where the bottom really is, and updated its overall calibration numbers accordingly. I.e., it might be that the new number was real, and what it was giving you before might have been optimistic. Range estimates are just that.

I've never had this happen to me, but I once did an overnight (actually, several nights since it was at 120v) range charge while visiting family some 220 miles away, and woke up to a severely degraded range report when the charging completed. Like, down over 30 miles. But then, as I stewed on alternate routes home, the range started improving. It was a pack balance issue. Ended up back where it was supposed to be, and no long term effects.

What you might do is do a range charge at some point, and let it settle for a little bit (not hours), and see where you end up. That will let the car learn where the top really is. Then drive it enough to get it back down to a normal Standard charge range, before leaving the car to sleep. No need for panic yet.
 

pharma5

Roadster F#25, Model 3 #36xx
Nov 22, 2011
555
113
central NJ
Or by running out of juice, the car just got a very credible understanding of where the bottom really is, and updated its overall calibration numbers accordingly. I.e., it might be that the new number was real, and what it was giving you before might have been optimistic. Range estimates are just that.

This.^ @PFLeFaou, had you taken this pack down to low state of charge previously, or was this first major road trip with it?

I don't recall the number, but taking the Roadster to low state of charge (down to ~20% on one key turn?) and then charging fully has been described as a way to recalibrate the pack's estimates of CAC and range. Helps ascertain 'bottom' and 'top'.
 

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
This.^ @PFLeFaou, had you taken this pack down to low state of charge previously, or was this first major road trip with it?

I don't recall the number, but taking the Roadster to low state of charge (down to ~20% on one key turn?) and then charging fully has been described as a way to recalibrate the pack's estimates of CAC and range. Helps ascertain 'bottom' and 'top'.

I own the car for a little less than 2 years and have taken the current pack (installed since September 2018) to a couple of trips. I rarely drive the battery down to red in order not to damage it – happened maybe 2-3 times since September 2018.

I've left town for the Christmas week but will pull the logs when I'm back home... to be continued.
 

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
All right -- bought the 4GB USB drive, formatted it (FAT32), created a VehicleLogs folder, made sure the car wasn't charging, key in the OFF position, plugged the drive in the car's USB port by the 12V outlet, drive blinking briefly, then... nothing. Nada. No message on the car's screen and of course nothing in the VehicleLogs folder. Also tried to remove the key completely -- same (absence of) results.

What am I doing wrong?? Any help greatly appreciated.

PF
 

bolosky

Member
May 5, 2009
701
591
I suspect that it's just a problem with the CAC algorithm not really knowing the battery's capacity. I've seen it more than once where I'd get the battery into a low-ish state and then park. When I'd come back to the car, the ideal miles would have dropped quite a bit. This would then be reflected in the overall range after a full charge. Luckily for me, I never ran out of charge, but it could have happened.

So, Tesla is probably right, there's nothing wrong with your battery other than it's old. It's just the range estimate that was off.
 

jfischer

Member
Feb 6, 2014
186
246
Houston
you can look at each bricks voltage and SOC level once you get a log generated. Any 4-8GB works fine. I got my 4GB one for the car ( actually came in a kit of 4 of them) off amazon.

You can look at the ahr.log file in this compressed file. It shows each brick and their status. Mine when I had a bad brick 21 looked like this...



ahr.log 2020-01-07 122457.png



Note the State of charge ( SOC) of the bad brick vs the rest of the bricks. This shows that THAT individual brick has faulty cells in it which will cause it not to fully charge as the other bricks do. Each brick should be 3-5% from each other, which shows a "balanced pack"


Also, Since you said you got the "PACK" replaced a year ago, its still under warranty ( 2 years currently) and I would bring it in to the SC for testing.
 
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PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
Try power cycling the VMS. That did the trick for me as mentioned here.

OK, I got the car back from the repair shop (unrelated issue) on Friday so I just tried to unplug-replug the VMS as shown in the other thread. Was very easy. BUT absolutely no effect on my USB drive recognition problem. The car screen shows nothing when I plug in the USB drive. Not even an error message.

Just to make sure I'm doing everything right: I've read the car key must be in the OFF position, right? Or completely removed? Should the small center screen of the car be on or off? If you just insert the key and don't turn it, the screen will remain off. If you turn it to "ignition" and turn it back to OFF without removing it, the screen will remain on.

Or maybe it's the USB drive that is the problem. I guess I'll buy a different one and retry.

Thanks for your help!
 

Roadster

JdeMO Powered
Dec 10, 2016
1,511
1,204
SoCal
Sorry, I meant: any error message as you inserted the USB drive, before you did the reboot?
No msgs of any kind whatsoever on the VDS before, during or after the USB drive was inserted. After performing the VMS reboot, no msgs whatsoever appeared on the VDS before insertion. However, soon after inserting the USB drive, I finally got the expected msg on the VDS: ""Memory stick transfer in progress. Please do not remove."

I've read the car key must be in the OFF position, right? Or completely removed?
The latter works for me.

Or maybe it's the USB drive that is the problem. I guess I'll buy a different one and retry.
Try a 2GB if you can find one. If someone in SF has a known good working memory stick, perhaps they can meet up with you. Best of luck!
 

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
However, soon after inserting the USB drive, I finally got the expected msg on the VDS: ""Memory stick transfer in progress. Please do not remove."

Can you please specify how long after approximately? 10 seconds? 1 minute?

The latter works for me.

Meaning, the screen goes from black/off to on with the "Memory stick transfer in progress. Please do not remove." message on it?

Thank you!
 

PFLeFaou

Member
Feb 23, 2018
81
76
San Francisco
The VDS msg pops up pretty quickly after insertion with the key completely removed
So just to be clear (and apologies for being annoying) – the screen being dark with the key completely removed, it will turn on and display the VDS message due to the insertion of the USB drive alone?

I ordered a different, 1GB drive. I'll update the thread once I try it.

Thank you!
 

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