Etiquette for stranded fellow Tesla

[TIppy]

If anything it would degrade a battery much more slowly. Powering your home from a Tesla uses a full charge over days - maybe a week if you're frugal. Static power wouldn't use as much power as driving unless you were acting as a battery back up for your whole neighborhood.

But it could be in addition to using it for driving. The average in the US is 30 kWh per day, so about 3 days for a 100 pack, another 120 cycles per year. The average use for a year is about 10,400 kWh. So 10, 400 kWh divided by 0.265 kWh per mile is 39,245 extra miles on the battery per year if the battery supplied all the energy needs for the house. It would probably be less than this. Charge during cheap rates and run off the battery otherwise.

Not to mention it would cut into their sales of powerwalls.

 

[D.E.]

If a flatbed tow is $200-300, that would be the best option as far as I am concerned. I’ve seen the aftermath of strap/chain tows that have gone badly. I’d offer people a ride to a safe place, offer to call if they lack that capability, but I would not attempt to tow their car with mine to save $300.

If I had family or kids with me, I would not stop unless there was evidence of an accident/fire or life threatening emergency. But a car with flashers on, no one knows what’s going on. Chances it is a good guy with a problem, a problem that it is unlikely we can fix anyway. But there is no way to know.

Suppose a thief stole Tesla, ran out of juice, and some yokel with a Tesla pulls over to help. The very best outcome would be that the yokel gets robbed and now is left stranded with the nonfunctioning stolen car. The worse outcomes are much worse.

Call 911 and let the emergency responders deal with it just as you might if the disabled car was any other make. If it was you that was on the side, that is what you’d expect.

And if you were the one on the side and some do gooder stops and pulls out a Harbor Freight tow strap, would you let him pull your car, with no earthly idea whether he knows what he’s doing? Life gets interesting being pulled along at 50+ MPH attached to someone else car with a 20 foot tow strap.

Me, I’ll do the flatbed.

 

[mswlogo]

If we had a way to share electrical energy between teslas, I could use my one car with free unlimited supercharging to juice up all my friends' Teslas...

Ugh.

The could charge a standard supercharging rate for the "transfer".

In the case of emergency it would be well worth the cost.

But it would discourage that type of usage. And if people did use it that way it would be profitable.

Everyone wins.

 

[rhumbliner]

Somebody’s thinking about this problem: https://electrek.co/2019/06/06/rivian-electric-pickup-truck-share-power-vehicle-to-vehicle-charging/

 

[aesculus]

There is no DC to AC converter in the car.

It's in there, you just cannot get access to it.

 

[brkaus]

I think it would be possible. The 240 volts ac that is the normal input to the charger has a peak of 350 volts. So the 400 volts max from the battery could probably feed the input side of the charger. They would just need a few contactors to change over from accepting to sourcing power through the charge port.

They probably don't want to make it easy to use the car as a source of power. People would be using it for back up which could degrade the battery more quickly.

The input side of the charger will not likely accept DC.

How does 240v have a peak of 350v? 240Vrms would have a higher peak, but US utilities have 240v peak to peak, not RMS.

It's in there, you just cannot get access to it.

So true! Wonder if they could program it to output 60hz?

 

[cduzz]

How long until tow trucks have the ability to L2 charge EVs?

A Generac GP5500 (a $700 generator) could put 7 miles on an X in 1/2 an hour, more for an S or 3; a bigger generator could charge it up even faster.

 

[TIppy]

The input side of the charger will not likely accept DC.

How does 240v have a peak of 350v? 240Vrms would have a higher peak, but US utilities have 240v peak to peak, not RMS.

The voltage at a 240 Vac receptacle is rms. I have a true rms voltmeter and it reads 240 volts.

The first thing the charger does is rectify the input ac voltage to dc. The applied dc voltage would pass through the bridge rectifier.

 

[TIppy]

How long until tow trucks have the ability to L2 charge EVs?

A Generac GP5500 (a $700 generator) could put 7 miles on an X in 1/2 an hour, more for an S or 3; a bigger generator could charge it up even faster.

AAA talked about doing this a few years ago, but I don't think anything came of it.

 

[mswlogo]

There is no DC to AC converter in the car.

the only practical thing to do on the road for a quick juice would be DC to DC.

DC to AC to AC to DC would have to be so large to charge quickly and even then it would be pretty inefficient. It has the AC to DC but the large DC to AC does not exist and would be costly.

we need a SC on wheels.

 

[aesculus]

AAA talked about doing this a few years ago, but I don't think anything came of it.

Yeah. They even had an article and a picture of a truck. When I contacted them about it they could not find a source for the service.
https://electrek.co/2016/09/06/aaa-ev-emergency-charging-truck/

 

[Decibelle]

Source: Electrek

This is what we need.

 

[cduzz]

the only practical thing to do on the road for a quick juice would be DC to DC.

DC to AC to AC to DC would have to be so large to charge quickly and even then it would be pretty inefficient. It has the AC to DC but the large DC to AC does not exist and would be costly.

we need a SC on wheels.

I disagree; I think that adding 5-10 miles is typically all that's necessary to get a car to a stationary charging location. Only a heroic moron would run their BEV flat with absolutely no idea of how they were going to get their next charge; it'd be interesting to get the "how close were they when they ran out" average number, but I'd be shocked if it was more than 10 miles.

As far as time (time == expense) goes, the loading / unloading / drive time is not trivial. I think a truck AC charging a BEV for 20-40 minutes (to add 10-30 miles) and escorting the BEV to a stationary charging point is comparable to a truck flat-bedding the same BEV to a charging location.

You could likely get by with a mobile service vehicle instead of a flatbed -- plenty of people with an ICE call for service when their car "won't start" and an ordinary truck/van filled with standard sized 12v batteries shows up and the tech installs one and gets the car back on the road.

 

[kingkong5]

Is it possible to physically push the Tesla? I guess without power you can't get it into Neutral, and can you steer and brake without power? If so, I would be happy to help push the car to the charger, to help out a stranded motorist.

 

[TIppy]

Is it possible to physically push the Tesla? I guess without power you can't get it into Neutral, and can you steer and brake without power? If so, I would be happy to help push the car to the charger, to help out a stranded motorist.

I think it depends on how long it has been sitting since zero miles. I remember seeing a video by Bjorn Nyland where he ran out of juice, but there was a convenience store in sight. He got out and pushed his car there and charged just enough to get to a supercharger. It took a while because it was a standard outlet that provided maybe 3 or 4 miles per hour.

On another of his videos, he wasn't close to an outlet and had to call a flatbed. He had to wait so long the car went into battery preservation mode. He couldn't even get it into tow mode. The tow truck operator had to forcible drag it onto the truck.

 

[cypho]

If the car can be put into gear your can transfer a charge via regen. Tie trailer hitch to tow hook and give it a tug.

 

[TIppy]

If the car can be put into gear your can transfer a charge via regen. Tie trailer hitch to tow hook and give it a tug.

The manual says there is a fire danger if you tow the car. It may be that the car isn't prepared to properly thermal manage charging during an extended regen. Although, I don't see much of a difference from driving down a mountain road using regen.

 

[cypho]

The manual says there is a fire danger if you tow the car. It may be that the car isn't prepared to properly thermal manage charging during an extended regen.

Scary. Would that also mean there is a fire risk driving down/out of the mountains?

 

[TIppy]

Scary. Would that also mean there is a fire risk driving down/out of the mountains?

I made the same observation. Do you usually have to use 60kw of regen when you drive down a mountain road?

 

[whitex]

To bad there isn’t a way to “jump” them (give them some juice). I think it’s so rare it’s hard to justify hooks in the cars to allow such a thing.

I've posted about the utility of this for years. From a hardware perspective it seems that the only thing that would be required is an adapter for the "wall" end of the mobile charger that fits the charge port. The car would, obviously, need a software update to support this. I guess the need is rare enough that it's not worth their trouble. And possibly they don't want to send the message that people run out of juice often enough to warrant this technology.

Technically possible, Nissan has been talking about allowing your car to power your house. In Tesla's case, their free supercharging would be the biggest stumbling block - with free energy for life, you could power your house with daily supercharging, and potentially supplement your income by reselling your free charge to other Teslas (maybe just camp our at a busy supercharger, offer folks a charge for $50 instead of waiting in line, then you get in line, charge for free, then sell that charge again when done - people can get very creative).