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Try this, when your battery doesn't have enough to reach the Supercharger

Missile Toad

MSLR Wht/Blk/19 | OD 6/10/21 | RN11512
Aug 30, 2016
700
830
30.04, -95.16
I've been driving Teslas since 2016. On my first cross country trip in 2016, I drove the S 70 D down to 3 miles when I reached my third supercharger on the trip. Since then, I've been under 10 miles of range at least 20 times, mostly while on a trip.

These adventures occurred during the night, day, heat and cold, as well as with precipitation. Only a couple times have I done this in mountainous territory. I've really explored the envelope in a car from 10-58K miles of odometer readings. At least, through these conditions, I've discovered two things to consistently be true:
  1. The battery gauge is very precise, when reported in miles, at the lowermost levels of charge;
  2. Tesla, in the early stages of the trip, tends to give slightly conservative warnings to slow down (the ask is maybe 3-5 MPH slower than needed)
Despite all this, about 2 years ago, I did run the battery to 'shut down'. I was very light on the accelerator. And I would have made the supercharger, except that no one tells you that you also have to be very light on the regen. That's right, the regen caused my battery to barf. Apparently, the battery cannot take-in charge except at minimal levels when the battery reads 0-1 mile of charge.

Last night, I had 10 MPH headwinds, which contributed to my under-charging my battery for a short 50 mi drive. This time, I was aware that the 'off ramp' might not be my friend, and I resolved to have at least 1 mile of range on arrival (current car is '22 S with 7,000 mi and a NCA battery). But first, how, in the hell (you may ask), does a 400-mi range car get to this point?

Itinerary:
1. Start, in Austin, TX, with 390 mi;
2. Drive to the Houston 'City Centre', for a lunch break and 32A L2 charge, of 30 minutes;
3. Continue South to Missouri City, TX;
4. Drive North to College Station, TX ~ 110 mi
5. Opportunistically charge for 20 minutes at a hotel L2 charger 5 miles into my final leg to NE Houston;
6. Top off ~95 mi at the Waller Supercharger
7. Arrive NE Houston

The Waller V3 Supercharger is 45 miles away:
I started, from College Station, with 52 miles of range, knowing that I had headwinds on my way to the Supercharger. Warnings immediately appeared in my car's dashboard, as I accelerated to 72 MPH. I slowed, accordingly, to 65 MPH, about 5 MPH below posted limit, but faster than the car recommended I go. In about 5 minutes, I got the warning shown here.

I then drafted for 5-10 miles (Autopilot set to 4). But the draft vehicle was going 65-70 MPH, and it was still insufficient. So I dropped off.
Eventually, 15 miles in, I decided I'd go 48-53 in a 65 MPH posted area with my hazards operating. Traffic was light on this 2-lanes of Southbound traffic. Visibility was high in the late afternoon, and the road gently rose and fell in this slightly hilly portion of Texas. Traffic moved around and passed me, as I routinely watched the mirror for approaching high-speed traffic.

25 miles later, I had about 12 battery miles to cover the final 10 miles. So I resumed speeds about 5 MPH below posted limits and extinguished my hazards.

Some observations:
Tesla says that they've improved the routing algorithm to account for weather conditions. I think that the algorithm helps, but does not entirely account for the 10 MPH S headwind that I battled on my SSE heading. My car is clean, with mildly worn tires that are inflated per specifications. Despite construction, the road was almost entirely without defects. I had 'average' drag reductions from the currents of air produced by the 'herd' that was routinely passing me. In spite of this, during 70-75% of my drive, I was driving more than 5 MPH below the 'stay under 60' MPH warning that I'd initially gotten from Tesla.

The Tesla navigation frequently fails to note that Superchargers are located at a corner of a highway and a significant cross-road -- and provide sensible routing navigation instructions that allow for direct arrival. This results in sub-optimal within a common pattern in Texas:
  1. Overshoot the Supercharger while on the highway;
  2. Exit;
  3. Do a double left-turn under the highway 0.5-1 mile up;
  4. Return to the Supercharger, backtracking 0.5-1 mile on the service road to the highway.
I've seen three Superchargers in South Texas that Tesla Navigation fails to direct via the direct route, and instead performs steps 1-4. So, expect that this is common through the rest of Texas (not so much in other states). I recommend, you just follow the Bus-ees signs (the famous 'gas' station host to the Supercharger) to know which is the right exit to quickly arrive. Buc-ees has really figured out navigation in Texas.

Anyway, I'm here to tell you, that, in light traffic, and good conditions, just turn on your hazard lights. Slow down. Watch your mirror. Yes, as an occasional speeder, it feels, weird, wrong, abominable. But, it is far better than a) calling Tesla roadside assistance; b) getting towed; or c) asking strangers to help push your car to the charger. I'd rather wash my eyes with sand, than attempt to call Texas roadside assistance. But that might be because I've got 10X the experience with these cars than they do, and I know that they are wrong more often than correct. (Note, the questions that a newbie would ask, they are likely to be correct -- I've just run out of easy questions and patience long ago),

Oh, and yes, I made it with 2 miles to spare.

tempImageXuoEEC.jpg
 
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No one ever needs to discharge their battery this far, and I doubt it is good for it. Anyone with intelligence should be able to figure out that they can stop at an earlier charger and top up, and that can save you from being stuck at the side of the road and needing a flatbed. Obviously, it's your choice to gamble on making it to the next charger, and likely someday it will backfire when, for instance, you encounter a detour. Have fun, though, watching them winch your car onto the truck to haul you to the charger. In my experience, that kind of stuff only happens to inexperienced drivers, and those with a few miles on their cars never have it happen. Sounds like you might be just a slow learner.

Seldom does my car get below 30 miles, and it has never slowed me down on a trip or forced me to take an extra charge stop.
 
No one ever needs to discharge their battery this far,
I’d guess @Missile Toad drives this way more for the [ fun | challenge | excitement ] than out of any sense of necessity. It’s crazy people like this who unnecessarily push the envelope that expose the boundary conditions. I think it’s kinda fun reading about his forays.
 

Rocky_H

Well-Known Member
Feb 19, 2015
8,355
10,751
Boise, ID
I’d guess @Missile Toad drives this way more for the [ fun | challenge | excitement ] than out of any sense of necessity. It’s crazy people like this who unnecessarily push the envelope that expose the boundary conditions.
Yes, I'm sure it's intentional, but I just don't get why someone would enjoy playing Russian Roulette like that. It's all risk with no reward.
 

Missile Toad

MSLR Wht/Blk/19 | OD 6/10/21 | RN11512
Aug 30, 2016
700
830
30.04, -95.16
Sometimes, the options to charge are slim. This is in contrast with Napa. Note, that the College Station & Navasota area are on same scale, roughly 10 mi to a side. At any rate, life is full of options. And as for briefly low battery SoC, the battery on my last car showed roughly the median level of battery degradation. So, though a single data point, it seems as though low states of charge, held for no more than 30 minutes at a time, does not adversely affect battery longevity (note this is with NCA battery chemistry).
As I passed southbound, in Navasota, I made a go/no-go calculation. I calculated it to be doable, with some refinement in my driving style. Since I'm very familiar with where the bottom of the battery is, and traffic conditions were benign, I decided 'go'.

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Yes, I'm sure it's intentional, but I just don't get why someone would enjoy playing Russian Roulette like that. It's all risk with no reward.
I’m certainly not disagreeing with you, but to me, a lot of sports fall into the category of “all risk and no reward” (sky diving, free solo rock climbing, Friday night stock car racing, etc.) but there are certainly plenty of folks who engage in these activities. It’s just up to the individual as to what constitutes reward. :)
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
7,694
15,470
La Conner, WA
I’ve been all over the place and generally avoid arriving with single digits. I’d much rather charge for an extra 5 minutes than have to slow down and/or draft trucks in order to just barely make it to my destination.

Plus, I’ve arrived at a non-functioning supercharger site (the was listed as being operational) at 4%, only to have to charge on a wall plug for 40 minutes at midnight (and getting scolded by a Wawa employee) in order to make it to a different Supercharger. Not really my idea of fun/sport.
 

RTPEV

Active Member
Mar 21, 2016
1,755
2,353
Durham, NC
I always thought that with Lithium Ion batteries, it was not good for battery longevity to run it down that far. And as expensive as battery pack replacements are...
You're not wrong, but you're not right either.

The BMS will not let you run the battery down to a point where it will excessively shorten the battery's life (or worse). That's why it shuts the car down before it will let you do that. Of course the battery will continue to self-discharge after that point, so it's a good idea to plug in as soon as you can after you reach this point. If you do so, it's not a lot different than leaving it at a high state of charge (100%) occasionally for brief amounts of time. I just would avoid making it a habit and then letting it sit for days afterwards.
 

bradtem

Robocar consultant
Dec 18, 2018
677
792
Sunnyvale, CA
Never got this close. Once was predicted to get to SC with zero, so I pulled out my new CHAdeMO adapter and solved the problem. This is why you want the adapters -- to be more flexible. You see me charging at a Petro-Can with it in the profile picture.

That said, I have seen main reports of Teslas going as much as 20 miles beyond zero. You don't want to depend on that but it can reduce panic.

Another option I tried was to turn on Autopilot behind a slow truck, drafting it. The trucks very much don't like this. Good plan in a headwind though. You don't get a lot of extra range but over a decent distance it can handle it if you have to cross a charger desert. I don't suggest you dial the minimum follow distance as that's too close for safety, though it means better drafting. Again, the truckers don't like it and will stop you.

I am very surprised at the report that it won't do regen breaking when the battery is low. That makes no sense.
 
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Missile Toad

MSLR Wht/Blk/19 | OD 6/10/21 | RN11512
Aug 30, 2016
700
830
30.04, -95.16
I am very surprised at the report that it won't do regen breaking when the battery is low. That makes no sense.
It very much surprised me, as I dropped speed from 55 -> 30 MPH, on the ramp immediately next to the supercharger. It's a poor design choice by Tesla, as a wimpy regen can easily be remedied by a friction brake.
 

bradtem

Robocar consultant
Dec 18, 2018
677
792
Sunnyvale, CA
It very much surprised me, as I dropped speed from 55 -> 30 MPH, on the ramp immediately next to the supercharger. It's a poor design choice by Tesla, as a wimpy regen can easily be remedied by a friction brake.
No, what is odd is that a nearly empty battery is the most able to receive the high power of regen braking. Sometimes when you car is too full or too hot it will limit regen breaking, but I can't think of a reason to limit it when the battery is nearly empty.
 
The first thing you do when your in trouble needing a charge is to call up the graph on the screen.....set it to the 5 mile scale and start watching the right side of the graph which indicates your remaining miles.....this is shown in real time. . Drop your speed until it indicates enough miles to reach a SC. I once incountered this on I-10 coming into Indio, CA. I reached zero at the peak of elevation knowing it was 20 miles of mostly downhill till I got to the Indio SC. Feathering the accel to 20-30 miles per hour and using regen, I was able to go the 20 miles on zero indicated.....and this was at night and my buddies were scared to death.
 
Lol - whilst I'm not ready to try this in the Y, I used to do it regularly in the Civic

The Civic had a digital fuel gauge with maybe 12 bars on it. When the Bingo light came on I knew I had about 40 miles left in it, but after the last bar disappeared, I knew I had at least 12.5 miles in the tank still

How did I know this? By pushing past the zero bars for a couple of miles, then for four or five, then eight or so and the most I did was 12,5

Why did I do this? Well partly because there was an easy-off-on QT on the way to work (back when we actually went into the office) AND it had the lowest priced gas on the route, so I headed for that if I could. If I thought it was really out of range, there were other options and sometimes I bottled it and used one of them. Sometimes I had to use one of them

I think some of the comments here are a little harsh. I don't think the OP was doing this because of poor planning, but because he was experimenting AND passing on the knowledge learned. A bit like say buying a Y, then disassembling it into a pile of unusable parts, filming it and posting the videos for us to watch for free

So I'll say thanks for the info, although I won't be trying it myself ;)



The note about the U turn to get to the SC is thought provoking too as the US has intersections that are so big that back in the UK, we'd build an entire town in that footprint
 
I’d guess @Missile Toad drives this way more for the [ fun | challenge | excitement ] than out of any sense of necessity. It’s crazy people like this who unnecessarily push the envelope that expose the boundary conditions. I think it’s kinda fun reading about his forays.
Reminds me of the movie "And Justice For All", with Jack Warden's character, a dotty judge who likes to take chances, who entices Pacino's character into a helicopter jaunt out over water juuuust a little past the point of no return, then enjoys the challenge of trying to make it back to shore. (Spoiler - this time he didn't make it, by about 25 feet).
I for one don't find that fun. I shoot for 15 miles minimum. And usually 30, JFTHOI. You never know when an offramp is closed, a traffic jam, or the general perversity of nature.
And yes, I wear a belt AND suspenders.
 
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The note about the U turn to get to the SC is thought provoking too as the US has intersections that are so big that back in the UK, we'd build an entire town in that footprint

Maybe other states have something similar, but maybe it's a uniquely Texas thing like Jug Handles in New Jersey, but ... apparently the U turn lanes at junctions with separated grades are called Texas U Turns ... and it's surprising how often they get used

Efficient, but still not as efficient as roundabouts
 

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