On the highway: Unable to drive / Vehicle shutting down

[lithium366]

Hey foloks

I was driving on the highway this morning and suddenly car stopped responding to a acceleration pedal as well as lost all it’s regenerative breaking. Several errors and warnings were thrown while the car was coasting to the nearest shoulder:

BMS_a170: Acceleration and top speed reduced / Performance may be restored on next drive
DI_a137: Unable to drive / PULL OVER SAFELY
APP_w009: Automatic Emergency Braking is disabled
DI_a063: Vehicle shutting down / PULL OVER SAFELY

Then later car complained about low windshield washer fluid (it’s topped off and this warning disappeared later)

I stopped and put the car into P. Tried to switch back to D or R - nothing happened. Then I pressed a break and both wheel scroll buttons to do a restart - it took about 5-7 mins to restart but error messages didn’t clear up after I recycled the car and I was still not able to drive. I called for an emergency roadside assistance and 15 minutes later while I was waiting for them all errors cleared up and I was able to get home safely as car shifted to D. Right now I don’t have any messages on the screen

I scheduled service appointment but my local service center appears to be quite busy and only Jan 4 was available. I am happy to get home safely but now I am concerned regarding the safety of my next drives before my scheduled appointment.

 

[KenC]

Check the health of the 12V. When you get a group of seemingly unrelated errors, they could be spurious due to a faltering 12V.

I’ve started carrying a 9V battery in my pocket and a NOCO starter in the frunk, just in case, since batteries about my vintage seem to be failing.

 

[MediumFidelity]

I’ve started carrying a 9V battery in my pocket and a NOCO starter in the frunk, just in case, since batteries about my vintage seem to be failing.

If you supply 12V via the connector on the front bumper, will that charge the 12V battery? That would only be helpful in the case where something is wrong the power conversion units, and the car isn't charging the 12V battery on its own (so not a fault in the lead acid battery itself).

The 9V battery is a good idea. We've been on some hikes where a dead 12V battery would have been trouble. I understand a lot of the "why" this is an issue, but still pretty crazy to think a car that is mostly battery by weight can fall victim to a lead acid battery dying.

I saw some discussion on Reddit about how Tesla treats the 12V battery, sounds like there was some abuse in earlier versions of the car/firmware. I wonder if anything came of this:
https://twitter.com/elonmusk/status/1238948776775049216?s=20

 

[JCtx]

Hey OP, year and mileage of your car? Hope it's not a new (or newer) one. I didn't know about a freaking 12V battery until recently. A Tesla guy said it powers all lighting and electronics, so car would be dead without it indeed. I was really surprised by that, but at least it doesn't appear to be a wide-spread issue. But I want to know how you can charge that sucker, especially when car is not being used, to make sure it's not getting sulfated due to a low charge.

 

[brkaus]

If you supply 12V via the connector on the front bumper, will that charge the 12V battery? That would only be helpful in the case where something is wrong the power conversion units, and the car isn't charging the 12V battery on its own (so not a fault in the lead acid battery itself).

The 9V battery is a good idea. We've been on some hikes where a dead 12V battery would have been trouble. I understand a lot of the "why" this is an issue, but still pretty crazy to think a car that is mostly battery by weight can fall victim to a lead acid battery dying.

I saw some discussion on Reddit about how Tesla treats the 12V battery, sounds like there was some abuse in earlier versions of the car/firmware. I wonder if anything came of this:
https://twitter.com/elonmusk/status/1238948776775049216?s=20

No, the connector will not charge the 12v battery. It just connects to the motor to open the frunk. But the 12v battery is very easily accessible for charging or replacement once the trunk is open.

I too would suspect the 12v if the car is around 18-24 months old.

 

[lithium366]

It’s a 2020 Car, have 14k miles on it and it is located in Southern California so really I don’t see good reasons for 12v battery to fail that soon but def will check!

 

[brkaus]

It’s a 2020 Car, have 14k miles on it and it is located in Southern California so really I don’t see good reasons for 12v battery to fail that soon but def will check!

Agree. mine failed at 20k miles but 18 months.

 

[lithium366]

Why such a sophisticated car will not tell if 12v battery is in a bad shape?

 

[vjason]

I owned 2 Priuses and they both started going similarly crazy when the 12V was near death. Took ~5 years though.

My 3 just turned 25 months old (26K miles) and I've been eyeing it suspiciously for a few weeks despite no issues. My luck it will die on the way to the coast Friday in the middle of nowhere. Alas, it is what it is.

 

[vickh]

Why such a sophisticated car will not tell if 12v battery is in a bad shape?

I've been using a voltmeter and had battery replaced @ less than 12 months b/c tech smelt sulphur.

Please post @elon above. Atleast a battery health display till they figure out what's the problem.

 

[brkaus]

They have logic to detect and report bad 12v. It just doesn’t catch all the cases (yet?) before they become fatal.

Mine had a shorted cell and died pretty quick. Not sure if that failure has a warning sign.

 

[skygraff]

If the 12v turns out to be the case, please let us know but, in the meantime, I hope you've either made other arrangements for transportation or, at least, taken the advice to carry a spare 12v or some other backup plans. I know it's hard to contact the service center directly but, since you had been in touch with roadside, there should be some record that shows this is a critical issue which needs to be addressed before you get stranded again; if they'd towed you, they'd have dealt with it immediately.

I've only once had my car claim it was going to stop moving while I was on a road but, fortunately, that was in a construction jam and it resolved itself before traffic began moving again. Aside from that, I had one instance where it wasn't going to let me use higher level functions when I stopped to charge (would've still driven but roadside said to try the full power off while plugged in and it reset) and another where it said no go after supercharging (drive unit failure so had to be towed but I was close to home). Suffice to say, I would not have been happy with a highway failure like yours and would've thanked Murphy and Clarence after limping home.

Keep us posted, please.

 

[JCtx]

With the stupid 12V battery such a critical component, unless it costs an arm and a leg, I'd probably replace it every 2 years for piece of mind. Does anybody have the exact battery model on the M3 LR? Is it an AGM battery? Just replaced the AGM H6 battery on my wife's car, which is pretty big, and it cost $150 at Walmart. It's a lot cheaper to me than getting stranded in the middle of nowhere at 100F+... or freezing... and no cell service.

Finally, what seems to be the issue with failing batteries? Overcharging, undercharging, or just defective? If they're good batteries, like from Johnson Controls (now Clarios), it might be overcharging, since it's rare they crap out that soon when being charged properly. Curious if anybody knows.

 

[brkaus]

Another thread here somewhere.

roughly $85. Not an AGM.

 

[iwannam3]

With the stupid 12V battery such a critical component, unless it costs an arm and a leg, I'd probably replace it every 2 years for piece of mind. Does anybody have the exact battery model on the M3 LR? Is it an AGM battery? Just replaced the AGM H6 battery on my wife's car, which is pretty big, and it cost $150 at Walmart. It's a lot cheaper to me than getting stranded in the middle of nowhere at 100F+... or freezing... and no cell service.

Finally, what seems to be the issue with failing batteries? Overcharging, undercharging, or just defective? If they're good batteries, like from Johnson Controls (now Clarios), it might be overcharging, since it's rare they crap out that soon when being charged properly. Curious if anybody knows.

$85 at Tesla, no core charge. Need to roll down windows and open doors and disconnect 12 v under rear seat before removing battery. go to Tesla maintenance for procedure. Don't just yank out battery.

 

[MediumFidelity]

$85 at Tesla, no core charge. Need to roll down windows and open doors and disconnect 12 v under rear seat before removing battery. go to Tesla maintenance for procedure. Don't just yank out battery.

FYI, Ohmmu has the procedure (from Telsa) documented on their site: https://www.ohmmu.com/model3install

Accessing the penthouse under the rear seat is pretty easy.

 

[TLLMRRJ]

Why such a sophisticated car will not tell if 12v battery is in a bad shape?

That's a Bingo!

But somehow the programmers can take the time to make the car reject 3rd party batteries.

 

[android04]

That's a Bingo!

But somehow the programmers can take the time to make the car reject 3rd party batteries.

The programmers didn't do that. Their algorithm to detect a failing battery was tricked from charging a battery that has 2x the capacity as the OEM. The algorithm thinks that the extra energy sent to charge the (bigger lithium iron phosphate) is wasted due to a shorted cell. That's why Ohmmu revised the BMS in their batteries as well as reduced the capacity and made them lighter.

 

[android04]

With the stupid 12V battery such a critical component, unless it costs an arm and a leg, I'd probably replace it every 2 years for piece of mind. Does anybody have the exact battery model on the M3 LR? Is it an AGM battery? Just replaced the AGM H6 battery on my wife's car, which is pretty big, and it cost $150 at Walmart. It's a lot cheaper to me than getting stranded in the middle of nowhere at 100F+... or freezing... and no cell service.

Finally, what seems to be the issue with failing batteries? Overcharging, undercharging, or just defective? If they're good batteries, like from Johnson Controls (now Clarios), it might be overcharging, since it's rare they crap out that soon when being charged properly. Curious if anybody knows.

This is directly from the Hankook battery catalog (manufacturer of the OEM battery). The battery is Group Size 51R. The listing doesn't seem to indicate that the battery is AGM but only Maintenance Free. However, I now believe that the battery is AGM because I've been monitoring the voltage in different conditions and Tesla uses charge and float voltages for an AGM battery.

 

[JCtx]

$85 at Tesla, no core charge. Go to Tesla maintenance for procedure. Don't just yank out battery.

For that price, and from Tesla, it has to be a flooded-cell battery. And of course nobody would just yank out the battery like an ICE car. Ha ha. Thanks for the info.

This is directly from the Hankook battery catalog (manufacturer of the OEM battery). The battery is Group Size 51R.

Excellent info; thank you. As I commented above, for that price from an OEM, I have zero doubt it's just a flooded cell. Cheapest AGM 51Rs are close to $200. Having said that, AGM batteries are more prone to damage from overcharging (their highest safe voltage is slightly lower than wet-cells). And from the many 12V battery failures in less than 2 years, I suspect Tesla is inadvertently overcharging those batteries somehow, so probably not a good idea to put an AGM. And for $85, I'd probably just put an identical one, to avoid any potential issues with incompatible batteries. Thank you for the info too. By the way, I'd probably replace the battery after 2 years, especially if I keep reading about such failures. Hopefully 2021 cars have revised software in that regard; we'll see.

Finally, thank you to the person who posted the service manual procedure. It never mentioned removal of the positive battery post, but I assume it's immediately after removing the negative one, since there's no more mention of that. It's not a well written manual. Typically you see that from bad translations, but here it was just plain badly done, especially for an EV, which is new technology, and need clearer instructions. Oh well. At least it's better than nothing. Ha ha.