Driving the car to -7% SOC

Driving the car to -7% SOC

So the other day a mobile ranger, that came to fix some panel gap problems of the trunk and fix some wind noise coming from a gasket seal on near the passenger side wiper insert near the frunk, told me he heard some guy drove his Model 3 down to -7% SOC before charging.

The discussion was following my story of reduced range crossing the Adirondacks from a supercharger to another going from 70% to almost 5% instead of 15% while the outside temp was dropping suddenly from 5 to 6 degrees down to almost freezing. Managed to do it by reducing speed and heating but he told me about this guy who drove it down to -7%.

Have you ever tried that or got into a similar situation?

Bighorn | 19 octobre 2019

There was talk early on of someone going 17 miles past zero, but plenty of people have run out at zero or even slightly above zero since, so much effort has been expended to dissuade people from thinking they have a buffer past zero.

Bighorn | 19 octobre 2019

And yes, I’ve gone negative out if necessity early on. About 5 miles, but I got over the palpitations fairly quickly as I arrived at a charger occupied by EM, family, and body guards.

vmulla | 19 octobre 2019

I have put myself in such bad circumstances with my S and X. I went past zero. I will not say how much I was able to drive past zero. Just don’t do it, and do not share that info.

I went as low as 10 mile range on my 3 (~3% SOC), that is bad enough.

Frank99 | 19 octobre 2019

Yeah, I got down to 3 miles of range left on one trip. My understanding (though I never plan on finding out) is that there is a margin that will allow you to drive (at possibly reduced power/speed) for a short distance after zero - but I have no idea how far that is.

With my Gas cars, soon after buying them I generally put a 5 gallon can of gas in the back and drive it until it dies to see where it dies relative to 'E' on the gauge. My Expedition has almost 5 gallons of gas in the tank when the gauge hits 'E' (probably to protect the fuel pump); my Civic would only go about 20 miles after 'E' (about half-a-gallon). I haven't figured out how to do that in the Tesla yet....

Bighorn | 19 octobre 2019

Like I said, some have run out of energy on the plus side of zero. Thought to be more likely with older batteries, but it should disavow everybody of the notion of a reliable buffer past zero.

Frank99 | 19 octobre 2019

"reliable buffer past zero"
LOL, I 100% agree.

walnotr | 19 octobre 2019

The supercharger network is built out so well now it seems like getting to 0% should almost take a willful act to do so. I have only had two instances where I was concerned, but even on those legs, driving conservatively made it with plenty of battery to the next supercharger.

Frank99 | 19 octobre 2019

>>> driving conservatively
Precisely. When I made it to the SC with 3 miles left, the car told me 100 miles previously to slow down - and I was watching the expected range for the whole 100 miles, driving as fast as I could that still kept a positive range left at the SC. The last 10 miles, I was going the speed limit in the right lane - which p*ssed off other people on the freeway (the right lane is normally reserved for those only going 10 mph over the speed limit).

spuzzz123 | 19 octobre 2019

@Walnotr “should almost take a willful act to do so.”

My close call on a road trip was caused by a detour resulting from a bad accident on a freeway bridge in West Virginia. The detour took us 50 miles longer than planned as we took backroads in the opposite direction to find another bridge over the river. This is probably a rare convergence of circumstances...the accident had to be recent enough that my navigator did not yet “know” about it (or it would routed me around earlier). But the nature of supercharging speed encourages us to arrive with a fairly low SOC to minimize charging wait times. So that leads me to believe there may be a few of these kinds of close calls that aren’t necessarily willful acts.

gmr6415 | 20 octobre 2019

When purposely trying to bring SOC down to around 10% to see if the 100% down to 10% a few times in a row would do any sort of recalibration of the battery indicator I noticed that in the 10% range, when looking at the energy graph, the consumption dropped substantially, so I assumed the BMS was adjusting to the circumstances.

I was making loops between two exit ramps about 5 miles apart at 70 to 75mph so my driving and the conditions were fairly consistent. I chose that route because I can get off at either exit, and i'm only about 4 miles from home where I could plug in, so my risk was low.

LR RWD...generally at 70 to 75mph on flat road with an ambient temperature in the 90˚ range (Central Florida) and cold tire pressure set to 45psi I use around 220 to 230Wh/mi. Obviously that depends on wind speed and direction as well as traffic patterns and other uncontrollable factors.

During my "discharge loops" while watching the energy graph, set on 5 miles/average, I noticed my average Wh/mi usage dropped down into the 180Wh/mi range. I also noticed that the 5 miles between exit ramps was only knocking around 3 miles off of the miles remaining shown on the guess-o-meter rather than the 5 miles I was actually driving on each leg of the loop.

These are all just rough observations. I didn't do this scientifically because I had no idea of the results prior to setting out. In fact it was just a thought as I was going through the process to take a look at the energy graph, then I noticed the miles being knocked off the guess-o-meter seemed to match up with what I was seeing on the energy graph. Boy did I get a nasty pop up on the touch screen when I arrived home and put the car in park warning me that if I didn't charge immediately I may cause serious damage to the battery. I was down to 6% when I got home.

My conclusion, the BMS will intervene at the lower end of SOC. Doing the 100% down to 10% three times in a row did nothing to change the read out of the guess-o-meter in my case.

What I have found made changes to the read out on the guess-o-meter: (1) fell asleep at a supercharger late one night with the charge set to 100% and woke up hours later to see my SOC at 310 for the first time in months (2) went on vacation and left the car plugged in with the charge max set to 50% in the Florida heat where the car was dropping SOC because of phantom drain and topping off charge a couple times a day...when I arrived home and charged to 90% I got 279 miles for the first time in months.

Maxxer | 20 octobre 2019

How much idle fees you had from falling asleep at the supercharger stall? Lol

And the 5miles mileage 3 miles consumed is interesting.
I had exactly the opposite during my roadtrip consuming 10 miles while driving 7 at 5 degrees celcius

walnotr | 20 octobre 2019

I will be the first to admit unforeseen circumstances can throw a wrench in the works. My wife had an experience with range anxiety when she had to make an unplanned side trip and found herself with 6% battery and going around in circles trying to find the parking garage with the supercharger. It was an an error on her part because before making the side trip she charged enough for what she thought would be enough to make the round trip and took off. Needless to say, her lead foot and environmental factors all combined to give her a lesson in looking at more than the “mileage” on the display.

Part of planning long distance travel now includes keeping an eye on weather patterns, elevation changes, and of course travel distance between superchargers.

Unpleasant things happen to us all and I am not minimizing what can happen driving into the unknown. My point was it is hard to travel the interstates without coming across a supercharger every 120 - 150 miles. I90 is the exception for now.

GrumpyinAZ | 20 octobre 2019

Typical unforeseen circumstances: you're driving on the highway near the end of the route and will be at the Supercharger in about 20 minutes. 50 miles of range left - and then, BRAKELIGHTS in front of you that seem to go on for miles. No chance at diving for an exit. TRAPPED by some person's accident for more than an hour. Range observed dropping every few minutes. Temperatures plunging also. Will you make it????? It's the same story for relief of bodily functions.

Bighorn | 20 octobre 2019

Traffic jams rarely are the unexpected issue that rob you of charge. Typically, you have better efficiency putzing along if you know to ration the climate control. A missed exit or detour are the more common nail biting culprits. I’ve long since upped my arrival buffer from 5 to 15%. And trust me, you will make an illegal u-turn on the interstate if it means not being flat bedded.

vmulla | 20 octobre 2019

"you will make an illegal u-turn on the interstate if it means not being flat bedded." @bighorn


FISHEV | 20 octobre 2019

The range gauge on the Tesla seems like it is setup to provide a cushion on the lower end. I’ve inadvertently run the car down to as low as 2 miles and the gauge moves slower from 50-0 than 100-50. Encourage people to head to charging at 100-50 and then cut them slack on 50-0 so they don’t end up “bricking” their car.

The people who have tested range by running the battery to the point the car stops tend to get less then their rated range which is a cautionary to running it down.

gmr6415 | 20 octobre 2019

@Maxxer, no idle fees. I was the only car at that particular supercharger, so idle fees wouldn't apply, i.e., the stalls weren't over 50% full. The problem was that it was in a pay by the hour parking lot, so I got dinged on those fees. That said, it was after midnight and the parking fees were minimal.

pelkofer | 21 octobre 2019

"Traffic jams rarely are the unexpected issue that rob you of charge. Typically, you have better efficiency putzing along if you know to ration the climate control. "

This is one of the best features of an EV. Stop and go traffic actually saves your range, opposite of the ICE experience. Switch to seat warmers, kill the HVAC except to keep the windshield clear, switch on some nice music and relax.