Unisciti allacomunità

12V Battery warning and sudden shutdown on the highway

I was driving my wife and son back from his final JO water polo game, was just merging onto 101 Southbound. When I punched it to merge into traffic, I got the 12V battery warning, and then the car SUDDENLY AND COMPLETELY SHUT DOWN. No power at all. Thank God I was in the right lane and made it to the shoulder.

Ironically, I'm about 1 mile from the Tesla headquarters, and roadside assistance said it would be a 25 minute wait (this was after at least 10 minutes on the phone already).

WTF Tesla! A car should not just shut down that quickly without any warning - very dangerous! Obviously there is a single point of failure in the electrical system that just simply shouldn't exist. This is a total failure in engineering!

I see that others had a good experience with customer service. My experience is anything but good right now!

"WTF Tesla! A car should not just shut down that quickly without any warning - very dangerous! Obviously there is a single point of failure in the electrical system that just simply shouldn't exist. This is a total failure in engineering!"

Right, because when an ICE has engine trouble and suddenly shuts down as you are getting on the highway, an invisible, second engine instantly kick in and keeps you moving safely until you fix the main engine...

Yes in the days of the pony express, horses would occasionally drop dead in the middle of a delivery. So you can't be upset about this problem with your MS. Now let's all get back to posting how great Tesla is.

Edmunds had a similar issue on an on-ramp IIRC. Our 12-volt failure gave us time to drift to the side. Tesla had to come 190 miles each way to get the car. ICE engines are pretty reliable these days except when they run out of fuel. This isn't a pattern for the MS - although all of the first ~5,000 or so cars needed replacement 12-volt batteries (or two), it was mostly a pro-active replacement by TM.

Those of us that experienced stranding failures due to the 12-volt system seem to be only a few if the reports on this forum are any indication. In any case, it behaves like an ICE engine failure - no more propulsion, but you can use whatever remaining momentum exists to get to the roadside. A couple people reported being stopped in traffic, but the car does not simply lock up. It is, however, too heavy to be pushed by hand like the our old VW's and Honda's that my wife loved to push for jump-starts when we were in high school.

This too shall pass. Sorry for your experience.

@Dave - You married your high school sweetheart? So cool. ;-)

Gas cars have effectively the same risk. If the ignition system fails, power loss is immediate too.

That said, if it happens to you in any car, you might say "WTF" too.

With some further 12V redundancy, I think the engineers at Tesla can pretty roundly eliminate this unlikely event, in a way that no gas car could touch.

Overall, I think EV architecture is already inherently lower risk of power failure.

Sorry indeed to hear this. May I ask what vintage the car is (when delivered)? And which version (60, 85, P85, P85+)?

PD. I had this exact problem and I was able to push the car quite easily.

Bob, though I had the 12v battery alerts, it turned out to be the main battery that was the problem.

Craig, I married my high school sweetheart too.

P85, and my VIN is below 2000.

I've never once in my life had an ICE car (I've had dozens of them over 30 years) fail so suddenly and summarily. This was an instantaneous failure. An ICE car that is even poorly maintained simply does not shut down suddenly with no warning.

Reality check - I paid over $100K for this car. How many of you out there have ever had a $100K+ car less than 2 years old suddenly fail??

@PBEndo - ;-)

I noticed the skateboard at Fremont was very easy to roll. I imagine if you're not in neutral, it's not going anywhere.

@rdalcanto - answer me this - have you ever in your life heard of a $100K+ car less than 2 years old fail like this? Your comment "when an ICE has engine trouble and suddenly shuts down as you are getting on the highway, an invisible, second engine instantly kick in and keeps you moving safely until you fix the main engine..." is simple minded and absurd.

@Bighorn. I had that exact problem. Since I was blocking the exit to a parking lot I pit the car in neutral ans quickly jumped out to push. It wouldn't budge. My first thought was "damn this car is heavy!" Then I realized it had to be in tow mode, or else it puts itself in park as soon as your butt leaves the seat. Once I put it tow mode I could push it easily by myself.

"Put the car in neutral and"

Well, when I bought my brand new Posche 911S ($120K) and drove it home two years ago I smelled gas inside the car. I called the dealer and they told me to park it, turn it off, and they would come get it. Turns out there was a fuel leak that could have burned up the entire car. So in my limited N=1 of ICE vehicles over 100K, it nearly killed me. Your problem seems trivial in comparison.

And yes, ICE cars under 2 years old costing over $100K do break down on the road and need a tow. Heck, look how many new Jaguars, Porsches, etc., catch fire without even being in an accident. Every new Porsche 991 GT3 had to have the engine replaced because they were having so many fires.


Your experience is reassuring. I pick up a S85 in Late September and had been concerned about "locking up" in an inconvenient spot. But, If I put it in neutral, and tow mode, it sounds like one man can push it from the driver's door frame and steer at the same time.

I guess this is one ICE "feature" that is nice to have.

My brand new ICE car has shut down in the middle of the road once. I barely made it to the right shoulder. It happened in the middle of the winter (in Canada), which made the whole experience much worse, not to mention that i had a little kid on the back seat. It turned out to be a failed fuel pump. The car immediately lost the power steering, etc. Scary sh.t.

I was stranded in my RX7 when the driver-side rear tire and half shaft bounced down the highway beside me. Fortunately, I made it to the shoulder and extinguished the burning brake fluid. Couldn't really move after that.

"I've never once in my life had an ICE car (I've had dozens of them over 30 years) fail so suddenly:

My Honda did just that many times but I never said WTF. Google Honda ignition switch recall.

First, OP, sorry for your experience. Any new car, EV or not, $100K or not, that abruptly quit working is at least a nuisance and certainly could be dangerous.

Let's look at this from a different perspective. rdalcanto's statement about a second engine...etc got me thinking. Tesla is in a unique position to build in redundancy that simply could not be done in an ICE car. If indeed it was the 12V battery that caused the problem, why not put in a second to act as a backup?

The cost would be minimal, they can be wired to both supply power. They can both be monitored. Should one go out a message to urge the driver to get service soon/immediately could be displayed as the car continued on. Because this is the bulk of reported issues that have stranded drivers, Tesla, because of its unique design could eliminate the problem fairly easily.

Because there are so many points of failure in and ICE car to build in the same level of redundancy would not be economically feasible.

All you EEs out there, what do you think?
....or more importantly, Tesla what do you think? O, and if this idea gets implemented I want compensation. I'm thinking a dog leash! :)

I am not sure we have enough technical information about the cause to offer specific design changes but agree redundancy could mitigate the risk. Like the old single engine fixed wing aircraft had duel ignition systems, now that was critical when it stopped!

Regarding tech. information as to cause. Agreed. That is why I prefaced with it being the actual battery.

@OP - I'll echo the sentiment of others that any vehicle can fail catastrophically without notice, no matter the cost. I know of one person who drove a brand new vehicle off the lot and the rear axle slid out onto the street (not a Tesla, this was in the '80s). I recall postings on this forum by people who'd owned Lambos or Ferraris that had to have engines replaced within a very short time of purchase.

There is a recurring theme here - people posting indignantly about how they paid $100k and this shouldn't happen, dammit... Well yeah, it shouldn't but a price tag is not a magic talisman against failure.

That being said, I like the idea of a redundant 12V if that is in fact currently a single point of failure.

@bobgriswold - sounds like the dreaded 'contactor' problem that KmanAuto just reported on youtube.

Classic symptom: punching it on an on-ramp. Car dies and reports a 12V error - which it isn't.

Tesla seems to have got to the root cause of this (bad component) but is not (yet) proactively replacing at-risk parts. Hopefully they will.

jjs - a few of us EE's posted elsewhere about the desirability of more redundancy.

Nick - the main HVIL contactor (relay) is also subject to single point failure risk, as is the 12V battery.

Some relays apparently had a defect that allowed the contacts to separate under extreme acceleration on an incline, which it sounds like Tesla will update. I think there is also some firmware tuning possible - filtering to improve recovery from chatter of the relay. This could make it more immune to brief disconnects, allowing it to bounce back and operate again quickly.

Tesla designed the high voltage interlock loop with multiple links in the chain for safety reasons, and it's a very smart design.

But they do have a chance to relatively inexpensively achieve protection from power loss that is far better than gas cars, and I think they should go for it.

In the meantime, it's important to keep in mind that the car is already more resistant power loss than a gas car.

BTW, with no load on the motor, the Model S is very easy to push on level ground - far easier than a gas car that's got a transmission engaged.

Even if in Drive, the Model S can roll either direction when no throttle is applied.

The OP has my sympathy because this has happened to me twice before in prior cars and I know how disturbing it can be.

The timing belt snapped on a Subaru I owned back in the 80s and that resulted in the engine shutting down while I was in the *middle* lane of a busy major highway. I got over to the side of the road safely but my heart was pounding for a while after.

The second time was about 8 years ago while on the highway with my 2nd gen Prius. All sorts of warning lights started flashing and it quickly decelerated. I was in the right lane of the highway so not as nerve wracking. Eventually I was able to coax it to go about 5 mph and get off the highway to the closest parking lot before it completely stopped. It turned out the alternator charging the 12v battery had failed and that battery powers all the control systems so the car was losing its mind in front of me.

I certainly won't be happy if my new S85 ever does something similar, but given my experience it won't be quite as novel an event.

Just to give some perspective, Mercedes had an episode several years ago where S-class cars would just shut down randomly due to software errors. I know someone who drove his brand new car out of the garage after delivery, onto the highway, and then suddenly lost all power including power steering and braking. He did still have the manual steering and brakes, which is extremely heavy, and managed to pull over safely. Mercedes was not the only company having that sort of problems at the time, advanced computer control was just being introduced in top of the line cars and giving all sorts of teething problems.

Personally, I have a Mercedes C220 and one day, when it was less than a year old, I suddenly lost almost all engine power while on my way to a wedding where I was the best man. Three of the four cilinders had stopped working due to a common problem with the fuel injectors which Mercedes had known about but had decided not to fix proactively. They were basically just waiting for them to break down rather than "risk" wasting too much money by replacing some that might not be bad after all. When I called assistance, their first response was "Which model? Oh, that will probably be the injectors then". I had just had a service checkup the week before.

Sudden ICE failures that I've had during my 33 years of driving my own cars. That resulted in immediately pulling over and getting either help or my own toolkit out. These are all on well maintained and often relatively new vehicles from major manufacturers.

1. Faulty ignition lead from distributor.
2. Failed fuel pump
3. Failed ignition warning system - shut down fuel injection ecu
4. Broken timing belt tensioner - 500 metres from the service dept, 60,000km service. Bent 16 valves and was off the road for 8 weeks under warranty repair
5. Failed water pump. Brand new from Porsche 1 week old
6. Water in fuel
7. Failed clutch pressure plate
8. Failed coolant hose - 3 separate instances with 3 vehicles.
9. Broken fan belt - road debris
10. Failed alternators (x2 different vehicles) ok not an immediate stop but effectively stuck
11. Wiring harness failure - disconnected starter solenoid and unable to start
12. Loose air intake (2km from leaving service) caused sudden engine shutdown as the ecu was confused
13. Failed clutch slave
14. Sudden transmission lockup - my brothers car with a DSG gearbox. Car was unmoveable in the middle of the road with all four wheels locked

Cost of the car really has not too much to do with failures.

Formula 1 spends hundreds of millions of dollars on parts and they are designed to NOT fail, but as you guessed it, they do fail.
Happened in the past weeks to MB Formula 1 team, car started on fire due to faulty part.

All parts on F1 cars are totally engineered to not fail, this is like number 1 priority and with all the money and hundreds of the finest engineers they still fail until they car find the root cause and redesign.

So money is not the issue.

@OP: What matters is not whether this happened to you (sorry, but you're not the center of the universe) but whether this happens more often in the Model S than it happens in comparative ICE cars. We have no evidence that it does.

I will note that in most ICE cars, a part can fail catastrophically causing an eventual shutdown as the engine burns up or a major part breaks up, with no warning. The MS on the other hand, has a huge amount of monitoring and diagnostics built in, and can choose to shut down rather than producing catastrophic damage. Better for the driver and better for the car.

X Deutschland Site Besuchen