Car shut down with 11% remaining

[ClaytonG7]

Hey,

I just got a used 2014 60 Tesla from Tesla 2 weeks ago. On a trip, I followed the map and was nervous about its the suggestion of arriving with 5% to a supercharge station but I figured I would listen to the car. About 14 miles away from the station, the car shut down within 10-second notice to pull to the side. Only another warning was reduced speed under 70 mph to reach in middle at around 50% which I quickly did.

The center console was on for a little and then also was lost. I had to get the 12v jumped before being able to charge it.

What occurred here? Is it normal for the car to shut down before hitting 0%? My 100% range seems to only be 177.4 miles and knowing that at 11% the car is going just shut down means that my range is far less.

 

[BigNick]

Not normal.
If I had to guess you have a weak string of cells in one of your battery pack modules. Once any string of 74 cells reaches the shutdown threshold, the car will shut down. If it is shutting down with mileage “left to go”, that is not normal and you should have your pack checked.

Also worth a read: Sudden Loss Of Range With 2019.16.x Software

 

[ClaytonG7]

Does the 12v battery get damaged when the car runs out of power? Since then, a warning has been displaying that it needs to be replaced. Got a "Service Estimate" via email today for total of $252.04

Is that battery not covered in 2-year used warranty? I just took delivery of it two weeks ago.

 

[Dithermaster]

The high-voltage pack supports the 12 VDC battery until you're down to 20%, then it's on its own. If the car has not yet detected it is bad, but it is, then suddenly you'll get a bunch of warnings, and if it continues to have issues, it will shut down the car. I had this happen once (in the bitter cold polar vortex, with heater on full). It sounds like this is what happened to you too.

 

[VikH]

Bjorn Nyland has posted videos about this issue. The battery pack likely is out of balance. I would push on Tesla SC to look at this and cover your 12V replacement.

 

[Chaserr]

Your 12v should be covered by warranty if for no other reason than just because it's supposed to last more than 2 weeks. It doesn't get damaged when the main pack is low on power but it won't be able to recharge itself and if it was already going bad that would help it along.

Have Tesla cover the 12v when they look at your main battery. They sold you a running car and making you buy a 12v 2 weeks into ownership is some shady used car corner lot BS.

 

[ewoodrick]

The high-voltage pack supports the 12 VDC battery until you're down to 20%, then it's on its own. If the car has not yet detected it is bad, but it is, then suddenly you'll get a bunch of warnings, and if it continues to have issues, it will shut down the car. I had this happen once (in the bitter cold polar vortex, with heater on full). It sounds like this is what happened to you too.

That's what I'm thinking, it wasn't a big battery problem, it was a little one. The 12V batter died, which would have shut everything down. A big battery just stops the car, doesn't shut down the display.

Older car, not knowing the 12V battery history, it's very possible that it was on its last legs. a 12V jump would have been all that's needed.

 

[ClaytonG7]

The displays were on still after car shut down until I clicked turn off from the menu. Which didn't seem like it was the smart idea? Then they wouldn't come back on.

 

[MP3Mike]

Your 12v should be covered by warranty if for no other reason than just because it's supposed to last more than 2 weeks.

I have seen Tesla deny warranty coverage on the 12v battery if you ever run your HV pack to empty. Though in this case he has no way to know that it was empty, so it should be covered.

I suspect this is another case where the battery is starting to fail, first being "out of balance" and shutting down early, but not bad enough to meet Tesla's definition of failure. My guess is that it will fail in the next few months and Tesla will replace it.

 

[MP3Mike]

About 14 miles away from the station, the car shut down within 10-second notice to pull to the side.

By any chance were you accelerating when it shutdown? That can cause a voltage drop that will trigger the shutdown when it is near empty. (Though 11% really shouldn't be that low.)

 

[ClaytonG7]

I was accelerating uphill using cruise control. Does the car not display "Charge me" first? During the whole trip, the trip computer was at a similar % at reach. Warning of don't travel over 70 mpg displayed and that's when I set cruise around 68. It shut down and still had that I would reach my destination with 6%. Instead, I reached my destination on a flatbed.

 

[MP3Mike]

I was accelerating uphill using cruise control.

That probably contributed to the early shutdown. It probably caused a voltage drop in one of the modules that went below the cut-off. (It normally doesn't happen above 10%, and is more likely to happen the closer to 0% you are.)

 

[ClaytonG7]

So the cruise control doesn't understand that its going force itself into shut off? (This is a 2014 without AP)

 

[Jeff N]

The high-voltage pack supports the 12 VDC battery until you're down to 20%, then it's on its own.

What is your source for this?

It seems like you are saying that when the high-voltage pack is under 20% that the car no longer uses it’s DC to DC converter to supply 12V power and just runs the car’s 12V electronics and lighting off of whatever energy is stored in the 12V battery. That seems very unlikely to me.

 

[BrokerDon]

The high-voltage pack supports the 12 VDC battery until you're down to 20%, then it's on its own. If the car has not yet detected it is bad, but it is, then suddenly you'll get a bunch of warnings, and if it continues to have issues, it will shut down the car. I had this happen once (in the bitter cold polar vortex, with heater on full). It sounds like this is what happened to you too.

If this is true, that's another reason to seriously avoid letting your high-voltage ("HV") pack State of Charge ("SoC") to go below 20%... in addition to running your HV battery down causing other long term issues.

Best "road trip" advice is to:

1. use EVTripPlanner or ABetterRoutePlanner to plan your trip... and follow it's speed recommendations. Both of these websites will give you optimum speed for each leg or your trip and estimated SoC estimates so you can see how you're doing. Both of these have been much more accurate than Tesla's onboard navigation in our 2015 P85D with 21" Arachnids & Pilot Super Sport tires... and our "road trip" 19" Cyclones and Michelin MXM M&S rated "all season" tires
2. charge 15% to 20% MORE than Tesla navigation estimate to next Supercharger since WIND and high/low temperatures aren't in the navigation's calculations in my experience
3. watch your navigation's estimate of your SoC at your chosen destination... and adjust your speed to keep this estimated SoC above 20%... and ideally above 25%
4. SLOW DOWN and/or DRAFT a high profile vehicle with AutoPilot following distance set to 1 when your SoC estimate at navigation destination drops below 25%. This means you have to slow down enough to get your SoC estimate at navigation destination ABOVE (ideally) 25% or (worst case) 20%. Lowering your cruise control speed to 68 mph clearly wasn't enough. Yes I know, drafting "isn't safe" and will increase your chance of road debris damage... but IMHO this small risk better than the pain of a flat bed tow
5. turn on Range Mode if necessary. Cabin temperatures may become less comfortable but better than standing outside your Tesla waiting for a flat bed
6. Make sure your tires are properly inflated. On long Supercharger to Supercharger legs I make sure my tires are at 45 psi vs. 42 psi on the sticker on our door frame. Higher inflation will roll a little better without triggering an overpressure warning.

We've driven our P85D with our "road trip" 19" Cyclones and Michelin MXM M&S rated "all season" tires 200 actual road miles between the Page AZ to Blanding UT Superchargers by using these techniques. This scenic route through Monument Valley has NO other chargers except a "fall back" at Goulding's campground 2/3rd's of the way. Because I'd used EVTripPlanner and watched our SoC at Blanding carefully, we arrived with ~ 20% SoC.

Yes I know this takes more brain power than driving an ICE car... but IMHO so much more enjoyable on road trips with AutoPilot.

 

[Dithermaster]

What is your source for this?

It seems like you are saying that when the high-voltage pack is under 20% that the car no longer uses it’s DC to DC converter to supply 12V power and just runs the car’s 12V electronics and lighting off of whatever energy is stored in the 12V battery. That seems very unlikely to me.

A Tesla Service person told me this after my 12 VDC died and the car shut down during the polar vortex with heater on full and 5% range left on the HV and 2 miles left to my house. Take it with whatever faith or doubt that entails. I believed it, but I've had other folks tell me it's not true. Enough other things (Sentry, Camper Mode) also stop below 20% that I tend to believe it. Perhaps the DC-DC still helps run things but doesn't charge the 12 VDC. The word they used was "supports" which is why I used the same word in my post. Who knows what it means exactly. I've decided to not push range so closely when it's -20F outside (the HV would have gotten me home had the 12V not fallen over, and there had been zero warnings about the 12V being bad until about a minute before the car shut down).

 

[Tam]

...What is your source for this?...

I didn't save the references but owners have reported that Service Centers told them that at a low state of charge, the main battery pack would no longer supply 12V to your 12V battery and the 12V battery would be on its own.

It's not clear what qualifies "low" but I guess people got the number 20% from the screen message warning that Dog Mode stops working.

 

[Tam]

...Does the 12v battery get damaged when the car runs out of power?...

Your 12V battery is lead acid which can prone to damage at a low state of charge.

I've read that a Service Center gave the owner a hard time and threatened to not cover for dead 12V battery because the car ran down to zero miles on the battery gauge.

 

[tls]

I didn't save the references but owners have reported that Service Centers told them that at a low state of charge, the main battery pack would no longer supply 12V to your 12V battery and the 12V battery would be on its own.

How would that even work? They'd have to have a solenoid to isolate the 12V battery, like in an RV (I'm skeptical) or a variable-output-voltage DC-DC converter to "float" below the voltage of the low-voltage battery at its present state of charge.

Really?

 

[TIppy]

There is an anti-brick buffer of about 4kwhs below zero miles. When the battery gets to this level, all but the most essential systems are shut down. At this point the 12 volt battery is no longer charged and will run down rather quickly. If this happens, you will need to jump the 12 volt battery to charge the main pack.

The 12 volt battery is only about 400 wh, so there would be no need to stop charging it when 20% of ~80,000 wh remain in the main pack. Shutting down large power draws like ac helps.

Cruising at 70 mph on level ground is about 14 hp, but accelerating to 68 mph up a hill will draw much more power from the battery. The internal resistance of the cells at this low charge will cause the voltage from the pack to drop below the zero miles level during the high power draw. Also, the bms might have been out of calibration for your pack.