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> able to get a tow truck capable of transporting my car (turns out you need one that has a full bed because of the regenerative breaking Sounds incredibly sho

by dinom 3y ago

> able to get a tow truck capable of transporting my car (turns out you need one that has a full bed because of the regenerative breaking Sounds incredibly short-sighted that the regenerative braking can't be temporarily disabled by the driver... two people can push a "regular" car to a nearby gas station in a pinch. Even one person can push a smaller car around a parking lot if necessary. That said, they often send out full/flat bed tow trucks these days for almost any reason. Edit: fixed "breaking" to "braking"

deleted 3y ago
[deleted]
purpleidea 3y ago
Tesla cars are way heavier. Nobody is pushing one with their friend. Unless it's downhill.
- reaperman 3y ago
  I'd need to do some quick math to double-check but very rough ballpark estimates still make me think Teslas can be pushed by a single person. After all, a single strongman can pull a passenger airliner, and any car is nearly impossible to push uphill -- you have to really get some momentum built up first to let them coast up driveways/etc.
  - Reubachi 3y ago
    It's not about weight or incline, it's the mechanical gearing in the "transmission" that can't turn the wheels without 100 percent power from the engine. You'll be able to push it and think it's really heavy, but it's just the transmission fighting you. standards and automatic trans have neutral that disconnects driveshaft from engine, removing any resistance from the engaged gear. Most EVs either don't have neutral or a poor implementation of it, because of single gear transmission/direct drive.
    - dinom 3y ago
      > Most EVs either don't have neutral or a poor implementation of it, I'm sorry, do you mean that neutral and "car wash/freeroll mode" are not 100% equivalent? This really confounds me... if my car has a problem while driving down the road, I'd really like to have a chance of pushing it onto the shoulder if necessary. A car that you can't do this with sounds very poorly designed to me.
      - stetrain 3y ago
        They aren’t equivalent. Most EVs have a free roll mode, where you can push the car or take it through a car wash. You are still spinning the electric motors though. This is fine for low speeds and short distances but is not advised for towing, like with tow trucks that leave two of the car’s wheels on the ground.
- dinom 3y ago
  > Unless it's downhill. Wouldn't that be ok since the parent's root problem was no cell-phone signal? Edit: of course walking is an option too :-)
  - bumby 3y ago
    >To make matters worse I was in a mountain valley and had no phone signal I read the above as an indication that they were in a valley where mountains were blocking any chance of a signal. Going further "downhill" wouldn't help in that case.
    - dinom 3y ago
      Fair enough, I was thinking back to the time something similar happened to me "mid-mountain". This Tesla must've been in one heck of a stop where "hiking wasn’t an option as it was pretty hot and we had no water", lol. Does Tesla make a motocross bike?
      - bumby 3y ago
        Lack of cell signal is still a problem in some parts of the U.S. I can think of a few places within a couple hundred miles where I can drive 45 minutes or so without any signal. It's also an area where triple digit temperatures are common in the summer.
- giobox 3y ago
  You can push a tesla in most typical push situations. Sure its heavy, but its in the ballpark of pushing any large sedan or SUV, not just electric ones. You can enable free-rolling wheels in the car and push away, especially if you have luxury of two people pushing. The weight of a Tesla is not some unprecedented figure for a passenger car - a model 3 is no heavier than many BMW 5 series configurations etc. The far bigger problem for pushing EVs in my experience is blown pyro-fuses that lock the axle after crashes preventing the wheels from turning - a common issue after an EV shunt. This is why you will often see EVs "dragged" out of shunts by the recovery vehicle until they can get the locked wheels onto dollies. This is only an issue if the EV being pushed has been in an impact generally, but the bar for a pyrofuse blow seems to be low too - it will trip even if airbags haven't deployed. The wheels on many EV motor axles wont turn again until the pyrofuse is replaced. I think the earlier example that required a full recovery truck - that sounds exactly like a blown pyrofuse, which is by far the most common reason an EV ends up requiring a full lift/dollies rather than a simple tow on its own axles. This is also why you generally always smell burning in the cabin after a tesla shunt too - nothing to do with a battery fire, its the smell of the pyrofuse burning out under the rear passenger seat. > https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-shock-crash/ https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-s...
  - dinom 3y ago
    > You can enable free-roling wheels in the car and push away This was mentioned a little earlier and further down in the comment tree but many thanks to you too for clearing this up.
    - Reubachi 3y ago
      I'm racking my brain on this. Why is this not just called exactly what it is, "Neutral"? I just read about this feature which is advertised purely for car washes, and can be gotten into with a wierd combination of actions or "putting the car into neutral". Is it...not just going into neutral via disconecting a drive shaft?
      - 3y ago
e136 3y ago
Most cars have one or more clutches to put the car in neutral. This is required so the engine can idle while the car stands still, among other reasons. Electric cars don't need to idle and therefore don't have any clutches in the drivetrain. Adding clutches just for allowing the user to push around the car seems needlessly complicated and over optimizing for a scenario that will not occur for the majority of cars.
- dinom 3y ago
  > don't have any clutches in the drivetrain Wouldn't a clutch be unnecessary in this case... a complete disconnect from the drive train should suffice, no?
  - caconym_ 3y ago
    That's exactly what a clutch does. They show up in all sorts of places besides the third pedal "clutch" drivers of standard transmissions are familiar with, e.g. in part-time AWD systems, traditional automatic transmissions with planetary gears, torque converters and hybrid transmissions with lockup clutches for efficient cruising, and so on.
    - dinom 3y ago
      I understand that... so you're saying something like "unlocking hubs" would not suffice? Or they'd add too much cost to the vehicle?
      - caconym_ 3y ago
        Locking (wheel) hubs could certainly be used to disconnect the wheels from whatever drivetrain trouble lurks within, but they come with a whole lot of compromises: cost, weight, complexity, space, etc. Standard industry practice for vehicles that can't be towed with only two wheels immobilized is (and has been for decades iiuc) to flatbed tow them, so Tesla isn't really going against the grain here. I think it's a fine choice.
- 3y ago
caconym_ 3y ago
It's common for cars with AWD systems where the rear drivetrain can't be disconnected by a clutch to require flatbed towing, less because the car can't physically be moved with the power off and more because spinning the wheels at a sustained high speed will cause damage to the drivetrain and potentially the engine. E.g. my moldy old Subaru requires flatbed towing, because spinning the rear wheels while the fronts are immobile will destroy the limited-slip center diff, but it's totally possible to push it along with all four wheels on the ground. I think AWD Teslas have an independent motor and drivetrain for the rear wheels. Naively, one would expect that if you unload the rear axle motor/generator you could just tow the car with little resistance and no damage, but in practice the picture is probably more complicated. I would love to hear from an expert.
sib 3y ago
If you put the car in car wash mode, you would be able to push the car: Controls > Service > Car Wash Mode And then "Enable Free Roll"
- dinom 3y ago
  thank you
- firesteelrain 3y ago
  ... assuming you have battery (which he didn't)
  - dinom 3y ago
    Yeah, that's a fair point but isn't it true that a mostly discharged battery will still have enough charge to perform some limited functions. E.g. even in a normal car I think a dead battery can power the lights even though the starter only "clicks". Nonetheless, I'm a rather conservative type of person and see your point so in my "dream car" I might want a way to manually put the car in neutral (or free-roll mode, whatever you want to call it). That's why locking hubs came to my mind in a prior reply.
    - firesteelrain 3y ago
      For the Tesla, it shut itself off in this story. Regardless of whether it may have had some juice left
rdevsrex 3y ago
Yeah when I lived in South Africa, I saw people towing each other all the time with just a rope. Sure it was one of those flat threaded ropes, but it works.

by dinom 3y ago

deleted 3y ago

[deleted]

purpleidea 3y ago

Tesla cars are way heavier. Nobody is pushing one with their friend. Unless it's downhill.

reaperman 3y ago
I'd need to do some quick math to double-check but very rough ballpark estimates still make me think Teslas can be pushed by a single person. After all, a single strongman can pull a passenger airliner, and any car is nearly impossible to push uphill -- you have to really get some momentum built up first to let them coast up driveways/etc.
- Reubachi 3y ago
  It's not about weight or incline, it's the mechanical gearing in the "transmission" that can't turn the wheels without 100 percent power from the engine. You'll be able to push it and think it's really heavy, but it's just the transmission fighting you. standards and automatic trans have neutral that disconnects driveshaft from engine, removing any resistance from the engaged gear. Most EVs either don't have neutral or a poor implementation of it, because of single gear transmission/direct drive.
  - dinom 3y ago
    > Most EVs either don't have neutral or a poor implementation of it, I'm sorry, do you mean that neutral and "car wash/freeroll mode" are not 100% equivalent? This really confounds me... if my car has a problem while driving down the road, I'd really like to have a chance of pushing it onto the shoulder if necessary. A car that you can't do this with sounds very poorly designed to me.
    - stetrain 3y ago
      They aren’t equivalent. Most EVs have a free roll mode, where you can push the car or take it through a car wash. You are still spinning the electric motors though. This is fine for low speeds and short distances but is not advised for towing, like with tow trucks that leave two of the car’s wheels on the ground.
dinom 3y ago
> Unless it's downhill. Wouldn't that be ok since the parent's root problem was no cell-phone signal? Edit: of course walking is an option too :-)
- bumby 3y ago
  >To make matters worse I was in a mountain valley and had no phone signal I read the above as an indication that they were in a valley where mountains were blocking any chance of a signal. Going further "downhill" wouldn't help in that case.
  - dinom 3y ago
    Fair enough, I was thinking back to the time something similar happened to me "mid-mountain". This Tesla must've been in one heck of a stop where "hiking wasn’t an option as it was pretty hot and we had no water", lol. Does Tesla make a motocross bike?
    - bumby 3y ago
      Lack of cell signal is still a problem in some parts of the U.S. I can think of a few places within a couple hundred miles where I can drive 45 minutes or so without any signal. It's also an area where triple digit temperatures are common in the summer.
giobox 3y ago
You can push a tesla in most typical push situations. Sure its heavy, but its in the ballpark of pushing any large sedan or SUV, not just electric ones. You can enable free-rolling wheels in the car and push away, especially if you have luxury of two people pushing. The weight of a Tesla is not some unprecedented figure for a passenger car - a model 3 is no heavier than many BMW 5 series configurations etc. The far bigger problem for pushing EVs in my experience is blown pyro-fuses that lock the axle after crashes preventing the wheels from turning - a common issue after an EV shunt. This is why you will often see EVs "dragged" out of shunts by the recovery vehicle until they can get the locked wheels onto dollies. This is only an issue if the EV being pushed has been in an impact generally, but the bar for a pyrofuse blow seems to be low too - it will trip even if airbags haven't deployed. The wheels on many EV motor axles wont turn again until the pyrofuse is replaced. I think the earlier example that required a full recovery truck - that sounds exactly like a blown pyrofuse, which is by far the most common reason an EV ends up requiring a full lift/dollies rather than a simple tow on its own axles. This is also why you generally always smell burning in the cabin after a tesla shunt too - nothing to do with a battery fire, its the smell of the pyrofuse burning out under the rear passenger seat. > https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-shock-crash/ https://www.wired.com/story/evs-fire-pyroswitches-cut-risk-s...
- dinom 3y ago
  > You can enable free-roling wheels in the car and push away This was mentioned a little earlier and further down in the comment tree but many thanks to you too for clearing this up.
  - Reubachi 3y ago
    I'm racking my brain on this. Why is this not just called exactly what it is, "Neutral"? I just read about this feature which is advertised purely for car washes, and can be gotten into with a wierd combination of actions or "putting the car into neutral". Is it...not just going into neutral via disconecting a drive shaft?
    - 3y ago

e136 3y ago

Most cars have one or more clutches to put the car in neutral. This is required so the engine can idle while the car stands still, among other reasons. Electric cars don't need to idle and therefore don't have any clutches in the drivetrain. Adding clutches just for allowing the user to push around the car seems needlessly complicated and over optimizing for a scenario that will not occur for the majority of cars.

dinom 3y ago
> don't have any clutches in the drivetrain Wouldn't a clutch be unnecessary in this case... a complete disconnect from the drive train should suffice, no?
- caconym_ 3y ago
  That's exactly what a clutch does. They show up in all sorts of places besides the third pedal "clutch" drivers of standard transmissions are familiar with, e.g. in part-time AWD systems, traditional automatic transmissions with planetary gears, torque converters and hybrid transmissions with lockup clutches for efficient cruising, and so on.
  - dinom 3y ago
    I understand that... so you're saying something like "unlocking hubs" would not suffice? Or they'd add too much cost to the vehicle?
    - caconym_ 3y ago
      Locking (wheel) hubs could certainly be used to disconnect the wheels from whatever drivetrain trouble lurks within, but they come with a whole lot of compromises: cost, weight, complexity, space, etc. Standard industry practice for vehicles that can't be towed with only two wheels immobilized is (and has been for decades iiuc) to flatbed tow them, so Tesla isn't really going against the grain here. I think it's a fine choice.
3y ago

caconym_ 3y ago

It's common for cars with AWD systems where the rear drivetrain can't be disconnected by a clutch to require flatbed towing, less because the car can't physically be moved with the power off and more because spinning the wheels at a sustained high speed will cause damage to the drivetrain and potentially the engine. E.g. my moldy old Subaru requires flatbed towing, because spinning the rear wheels while the fronts are immobile will destroy the limited-slip center diff, but it's totally possible to push it along with all four wheels on the ground. I think AWD Teslas have an independent motor and drivetrain for the rear wheels. Naively, one would expect that if you unload the rear axle motor/generator you could just tow the car with little resistance and no damage, but in practice the picture is probably more complicated. I would love to hear from an expert.

sib 3y ago

If you put the car in car wash mode, you would be able to push the car: Controls > Service > Car Wash Mode And then "Enable Free Roll"

dinom 3y ago
thank you
firesteelrain 3y ago
... assuming you have battery (which he didn't)
- dinom 3y ago
  Yeah, that's a fair point but isn't it true that a mostly discharged battery will still have enough charge to perform some limited functions. E.g. even in a normal car I think a dead battery can power the lights even though the starter only "clicks". Nonetheless, I'm a rather conservative type of person and see your point so in my "dream car" I might want a way to manually put the car in neutral (or free-roll mode, whatever you want to call it). That's why locking hubs came to my mind in a prior reply.
  - firesteelrain 3y ago
    For the Tesla, it shut itself off in this story. Regardless of whether it may have had some juice left

rdevsrex 3y ago

Yeah when I lived in South Africa, I saw people towing each other all the time with just a rope. Sure it was one of those flat threaded ropes, but it works.