I'm the idiot whose Taycan was towed after running the SOC to 0%

[SWORDER]

TLDR
I ran my battery to zero and had to be towed. A few insights and questions follow.

Background
I make the trip between San Diego and Las Vegas quite frequently. The first leg of the eastbound trip is from my apartment in San Diego to an Electrify America in a little town called Hesperia up in the mountains. The trip is 130 miles.

I always drive in Sport Plus mode, Normal suspension, Normal ride height. When I begin the trip, the car always tells me that I have 200 miles of range left. So in other words, I give myself a 70 mile cushion. Despite ostensibly having 70 excess miles to work with, I always roll into the Hesperia EA with a low but comfortable 11 miles of range remaining.

The elevation of my start point in San Diego is near zero. The elevation in Hesperia is 3,100 ft so the trip is net uphill. I normally travel at around 75 mph.

Differences this Trip
I left earlier this time. Very little traffic. Average speed was in the 90's. It was 45 degrees outside. Chilly for Southern California I suppose, but by no means extreme.

Car hit 0 miles of range with a "park car immediately" message in Hesperia, six miles from my destination. I pulled into a Chevron and got a tow truck to get me the remaining six miles to my charger.

What it's like to be a Moron while Driving
At around 15% you get a friendly message telling you to mind your range. You've all seen that one. At somewhere around 5% you get a more sternly worded message indicating to charge immediately. This wasn't an option for me. It's not like there were any other chargers nearby according to my PlugShare app. The lowest number on the range indicator is 3 miles. You don't see 2 or 1. It goes from 3 immediately to a double dash ("--") for some reason. So it cheats you out of two miles. On the main console it shows zero:

A turtle icon appears on the screen which I assume is Taycan's way of saying, "I'll let you drive a tiny bit more but I'm going to make your life difficult until you feed me."

What it's like to be a Moron while Waiting for the Tow Truck
I had a fair amount of time to think about my poor choices. I initially thought, "I'm going to take one for the team. I'll drive slowly along this isolated/safe road in the direction of my EA charger, see how many miles past zero I can get before it quits, and report back to the Taycan forum with a result. After all, the closer I get the less distance I'll have to be towed, and who knows, it's only six miles to the charger so maybe I'll make it."

After doing a bit of Googling I decided against it. I read that you can damage your battery driving past zero and if you truly hit "real" zero your battery is permanently killed. So I just waited at Chevron for the tow.

Some Findings
There's so much contradictory information out there but from what I gather, there're two types of zero: FakeZero and RealZero. At FakeZero, there's still 15% SOC available which means that had I kept blasting toward my destination, presumably I would've made it, albeit in turtle mode. But driving below FakeZero damages the battery and isn't recommended. If you get to RealZero, your battery is toast.

There are posts on this site indicating that if you plug in to charge at 0%, the charge rate is ridiculously slow due to "preconditioning" that must take place first. This is false, at least at FakeZero. I plugged in at FakeZero and instantly started getting 250kW. In the time it took me to take a lap around Walmart and use the restroom, I was back at 80% SOC and I was on my way.

It's More Common than You Think
I asked my tow driver how often he tows EVs that stall out due to lack of charge. He said I was the first Porsche he's handled but he tows Tesla drivers all the time. And they, like me, all seem to stall out in the same place, after that big uphill climb leading into Hesperia. They check their range prior to the hill, it looks ok, they attempt the hill and run out of juice. And each time they tell the tow driver, "Man, I really thought I could make it." I think I said the same thing to him.

When I showed up at Electrify America there was a nice guy charging his ID4 who saw the my car being unloaded from the tow truck. He said, "How many miles short were you?" I told him six and he said that sounds about right. He'd had the same experience.

Negative Effects?
The car seems healthy with one notable exception. Now, when I charge to 100%, the range shows 189 instead of 207 (in Sport Plus mode). Not sure why the drop. Could it be that I damaged the battery? Possibly. But another possibility is that the range estimator simply reset itself. When I first got the car in June 2021, the 100% range was pegged to 189 miles then gradually crept up as I continued driving. Hopefully that'll happen again. We'll see.

Closing Questions and Thoughts
When I left San Diego, I had a 70 mile surplus (200 miles of range to cover 130 miles of distance) but that 70 mile surplus turned out to be a six mile deficit! That's a pretty big miscalculation. I assume the factors involved were: (a) 90+ cruising speed, (b) net uphill from 0 to 3,100 ft, (c) 45 degree temperature. Which of these is the most important factor? I'm not sure. The range estimator had no idea what my average speed was going to be, nor the fact that a major uphill climb was imminent so I can't really blame the tech. But is there some mathematical formula I can manually use myself to scale down the estimated range based on elevation differential, intended speed, etc.? Nothing exact of course but something rough maybe? I can't lie. Being able to drive only 124 miles on a near full charge kind of bums me out.

My fellow charger at EA was telling me that Tesla owners have the option to purchase this thing where if you run out of juice, you plug it into your car and you can get another few miles. That would've saved me, although man, it must be super heavy to carry around in your trunk. Anyway, does Porsche offer something like this?

Would there be any meaningful range benefit from setting the ride height to Low while on the freeway?

Thanks for listening and don't forget to check your range.

 

[Jhenson29]

Potential energy increase is around 6kWh or 7% of your usable battery. 90mph is what probably killed it.

 

[daveo4EV]

this is great information - thank you sincerely for sharing.

 

[notsofast]

This is the main reason I use the built in NAV, the range estimation with the NAV is usually very good as it takes elevation changes into account. Having somewhat exact range estimation also allows you to notice your are cutting it close while you can still do something (Range mode, speed, heat, AC etc) about it.

None of this goes to say that this will never happen to me. Thanks for sharing.

 

[VOLT4GE]

We appreciate you taking one for the team. As for lowering the chassis: when I go into range mode, the car automatically lowers. So I’d imagine it would have bought you a few miles.

 

[wurzitup]

Shit.....sucks this happened but you have the right attitude and grace telling it to the Forum like you have. I even had a chuckle. For sure, the biggest killer in my opinion was the speed.
One thought if it were me- I think I might pull over and beg to trickle charge at some kind persons 110V outlet to gain 6 miles to the charger. I would be loathe to load the car onto a flatbed for fear of scraping, even in lifted mode.
This had crossed my mind how ill deal with it first time it happens.
Thanks again.

 

[Marcad80]

1.5 miles per KWh… ya, you were hauling…

 

[feye]

Good story. I once stopped at a charger at a highway, not working. Drove on to the next one. Reduced speed and easily made it.

Lower temp is the biggest problem if you run the AC. I always get low consumption with easy cruising. Recently it got really cold and wet, had to use AC and the consumption (from 18 to 28 kWh/100km) exploded.

 

[outie]

Both speed and temperature. Was your heat on too? 45F is pretty damn cold in SoCal and is not just "chilly". We were at Joshua Tree on Presidents Day camping and it was 45-ish and super windy. Believe me, it was beyond just chilly.

 

[KTC]

Thanks for sharing. Glad you and the car are safe.

 

[Fish Fingers]

Was that not another post on here recently from someone who kept going even at zero soc in snail mode?

And even when 'real zero' is reached it isn't real zero as there was still charge in the batteries to stop them being bricked?

 

[batteredhaddock]

Having got to 0% and “your car is shutting down” once in my iPace (the only time I’d stupidly gone by its eta guestimate on the maps which is far less accurate than Taycan) I sympathise. Given that I was at 93.5% battery SoH after 3 years I don’t think that episode caused any significant battery deg. I actually made it to the charger through the power of clench so battery wasn’t at 0% for long.

Few things:
1) Agree with others, main culprit will have been the speed.
2) As my episode reminded me, whilst the GoM and Maps % are a guide, they are still estimates.
3) I’d keep an eye on your kW/100 miles (or mlies/kW) average as the key “will I make it” guide. Giving some contingency then if you assume the battery to be 80kW for Perf batt+ then you can easily work out in your head where you are and if you need to slow down to get the average consumption down. (I.e. 200 miles trip, if you are averaging over 40kWh/100 you are in trouble). Given my iPace had a very similar useable battery, I expect to be pretty at home with the realistic range using this method.
4) As per 2, Guess o Meter is an estimate based on past and recent driving. Your “189 miles range” is just an updated prediction after you drove it like a Porsche and nothing to do with the battery State of Health.
5) You clearly aren’t as attractive to unmarked police cars as me ??
6) Edit - Its a tortoise ?, not a turtle . Turtles can swim pretty bloody fast ? though perhaps an electric boat might get a turtle mode...Still, if you say you are "turtling" in the UK, you might get an odd look and the offer of some toilet roll...

Cheers

 

[B61]

Speed, definitely speed (and climbing uphill).
IMO, in Range mode (with ECO A/C), you might save enough SoC for those 6miles.

Thx for sharing.

 

[Scandinavian]

I always drive in Sport Plus mode, Normal suspension, Normal ride height. When I begin the trip, the car always tells me that I have 200 miles of range left. So in other words, I give myself a 70 mile cushion. Despite ostensibly having 70 excess miles to work with, I always roll into the Hesperia EA with a low but comfortable 11 miles of range remaining.

Sorry for your experience but great that you have shared this information. I agree with others here that speed is what has been the major factor here. There is normally quite a huge different when driving at normal speeds such as 56 mph and 75 mph. In some of the data I have seen the difference can be as much as 40 to 50%. The tests done by TeslaBjörn with many different EV’s. And travelling At 90 mph will consume much much more.

One question I have about the indicated range of 200 miles. Was this with the destination input on the cars nav system? Normally the cars system will take into account elevation changes along the route as well as weather and temperature. And what is the legal speed limit along the route, which I guess the car uses as a basis for calculations.

So a reduction of 40% and more would not be impossible if you drive at 90 mph instead of 75 mph. Probably even a bit more since the wind effect is not linear.

 

[f1eng]

I am having trouble posting this morning, I have tried this twice so far and got weird partial posts!
Here we go again:

Both speed and climbing will use more power.

I live in a valley and walk my dog on The Ridgeway a 5000 year old trail not far away. The road up there isn't ridiculously steep and it is twisty, so not high speed, but my actual range driving there is less than half what is predicted by my PHEV. I gain most of it back on the way home, of course, but need to have well over double the distance there on my range indicator before leaving if I don't want the petrol engine to have to start before I get there.
Plus my PHEV weighs 600kg less than a Taycan, so will use much less energy climbing a hill.

Aero drag force goes up with speed squared, so the drag force at 90mph is around 45% more than at 75mph. Power used is force times speed so in power terms the loss is proportional to speed cubed. There are obviously other things using power but the proportion of the power being used to fight aero drag at 90mph is 73% more than at 75.

Speed is always a huge hit on fuel consumption.

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