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It seems like the tire wear wouldn't be worth it. You're pulling the tires at almost 100 horsepower of energy transfer. Sure, neat for a video gag though.



Hah, don't try it in Europe either, max towing speed in Europe is 40km/h or 25mph.

I guess a tow truck with a bed that has a rolling road would be an idea, prop up the car so the weight of the car isn't actually exerting force that makes the wheels harder to turn/cause extra wear. Or the "rolling road" can be replaced be a contraption that attaches to the wheels by e.g. its rims, and spins it.


This would work but it would probably make more economic sense to carry a generator to the car than to carry a wheel spinner gizmo.


Plus in Europe it's forbidden to tow with a rope like he does. You must use a rigid link, like a bar or a tube.


It's only kinda sorta legal in the US.

But like speeding as long as you show decent discretion when doing it you'll be fine.


Not true, a rope is fine.


I don't think so. Most vehicles have virtually no braking power with the engine off. It's definitely completely forbidden in France to tow with a rope, and I'm pretty sure this applies to all or at least most of UE too. In Germany, even tow dollies are forbidden.


Towing rope is legal in Germany, but you are only allowed to tow a car to get it out of the way and to the nearest repair opportunity after it has broken down, not for general transport - for that, it needs to be completely off the ground.


> Most vehicles have virtually no braking power with the engine off

You just need to press the brakes harder. Like 3 times harder, not 30.

If you park in a slope and turn the engine off you can try braking after pumping the vacuum out - it works just fine.


If you’ve always used power assisted brakes and you’re not expecting to have to press really hard on the brakes it could easily lead you to rear end the car towing you if it stops suddenly. Also, without power assisted steering, modern cars are surprisingly difficult to control.


Ye especially the steering. Small steering wheel and lower gear ratio on modern cars makes them kinda unsafe in the event of power steering loss.


Until the tow truck hits the brakes…


I was once involved in towing a car using a partially-inflated water bed as a 'bumper'. We got there!


Old tire not on a rim is the classic item to use for that use case.


First day of statics - you can't push a rope.


Not necessarily forbidden, but there's a good reason for not towing with a rope. Especially at 70MPH (which is 112 kph)

Though towing a Tesla with regerative braking is the best case. You definitely wouldn't want to tow anything that can't brake or steer with a rope.


@Peloton, here is your next big idea


Hah, they should integrate the bike into the car and make the modern Flintstones car.


It’s likely fine, 65 kW is only ~85 HP. Simply maintaining highway speeds is ~25HP, so as far as the tire is concerned it’s the equivalent of mild acceleration or breaking.

The regenerative breaking system is likely designed for long mountain roads, so it might overheat but probably not.


Teslas will switch to friction brakes when regeneration limits (peak current or battery SOC) are exceeded. I’ve sustained constant 50kw regen while downhill through Appalachia passes, no issues, with the caveat that regen current is limited if the pack is cold until it approaches operating temperature (yellow dashed lines on the regen current display indicate your reduced regen capability).


Does this mean that when the battery is full you must use the brake pedal? Or does the software automatically apply the friction brakes when you back off the accelerator?


Regen braking is noticeably less powerful when your battery is nearly full, and you have to manually use your friction brakes more. Sounds like it might be a safety issue, but in any scenario where you use regen brakes you have more than enough time to switch to physical brakes if you want to.


that's correct. You don't get one pedal braking if it's not charging.


I don't think the brake pedal was being used in this test, though.


My understanding is that above 95% SOC, even if you’re not using the brake, regen will not occur and an error is presented to the user notifying them about regen limits.


Sure, so the car stops charging and still won't waste/damage its brakes in the tow.


Teslas have no resistor banks?

A great omission.


Why would a resistor bank be better than mechanical brakes? Both get rid of excess power as heat, and you probably need the mechanical brakes anyway.


> Why would a resistor bank be better than mechanical brakes?

Resistors don't wear out like frictional brakes do.


What is implied by the GP is that the cost of ownership for regenerative brakes is lower per joule.

That's obviously true when that joule is "reused" and not so obvious when it's dissipated. Mechanical brake pads have to be replaced but I assume there is wear on the (more expensive?) parts in a regen system too.


Electric braking has close to no wear, and much cheaper EVs use it.

A resistor bank with liquid cooling will be few kilogrammes at most.


A resistor bank of the required wattage would simply be a big lump of dead weight most of the time. And it would need its own cooling fan which would add even more weight.


There's a free 1000+ lb steel heatsink - the chassis of the car.


It wouldn't be, all teslas already have liquid cooling.

Few kilogrammes at most.


It isn't worth the complexity for the rare cases when it might be useful. Even if you live at the top of a mountain, the easier solution is to just not charge to 100% to account for your "free" energy gains when leaving.


65 kW is a little over 87 horsepower (parent previously claimed ~80 HP, now edited to 85).

To get 65 kW into the battery, you have mechanical and electrical conversion losses on top of that. The tires are seeing pretty close to 100HP.


That really depends on what the 65 kW being displayed represents. If it’s the AC power from the regenerative breaks that should be extremely efficient, post AC/DC conversion things look worse etc.


The article claim is pretty clear:

> putting back electricity into the batter[y] at a rate of 65 kW

The article could be wrong, of course.


It is worth it if you run out of battery away from a charger.


I anticipate a future where mobile road repair will carry their own massive batteries by default to restart dead EVs on the side of the road.


It'd be nice if those vehicles also were hybrids that could use the gas power plant to regen the aforementioned batteries.


A Tesla will regularly put 100hp or more into just accelerating to highway speeds on an onramp. It's not exactly a tire-shredder.


For 10 seconds at a time, of course. Our old Honda does the same. Both of those actions do in fact wear the tires, but fortunately for drivers, neither car merges onto a highway for hours at a time continuously (such as charging a Tesla might).




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