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Towing a Tesla at 70 MPH replenishes battery at fast charger rates
- Simulacra 5y agoWhat if they had a Tesla merry-go-round where instead of charging your Tesla, you connected it to this giant horizontal ferris wheel that spun it around and charged the battery? It could be wind powered!
- ojosilva 5y agoI guess conveyor belts under the wheels would have similar results, probably with less moving parts. But then... why bother, just plug the car to the power source making your marry-go-round go round! Otherwise this is a lot like putting salt on a birds tail to catch it... https://en.wikipedia.org/wiki/Salting_a_bird%27s_tail https://en.wikipedia.org/wiki/Salting_a_bird%27s_tail
- stavros 5y agoIs the argument that if you could have salted the tail you could have just caught the bird?
- dhosek 5y agoYou said this as a joke, but I found myself (at least for a little while) wondering whether this might be more efficient than having the wind turbine generate electricity and then have that electricity power the charger. But then I remembered that there is the cost of moving the relatively heavy vehicle on the merry-go-round and realized it wouldn't actually work.
- unknown_error 5y agoWhat if you had a driveable wind turbine? They have solar panels on Priuses, might as well add wind to Teslas. The faster you drive, the more wind there is! Now if you had a solar-powered Prius towing a wind-powered Tesla on the deck of a nuclear-powered carrier, you're just one creative accountant away from starting your own renewable defense company.
- Dylan16807 5y agoYou're still converting to electricity somewhere, and moving around electricity is vastly more efficient than moving around mechanical energy. Always convert at the source. Even when your output is mechanical it's hard to beat electrical wires. But here the output is battery charge; no contest.
- Simulacra 5y agoYes, I did say that as a joke, but I guess some took it too seriously. It would never work but it was the first image that came to mind, a merry go round of Tesla's.
- hughrr 5y agoI had a similar idea which involved a large amount of gerbils in a giant wheel. They can convert sunflower seeds (which are of course solar powered) into energy 24/7. Thanks to your stroke of genius instead of using a generator and charging your EV you can just put a wheel next to it and leave the Tesla on it now. I haven’t worked out what to do with half a ton of gerbil corpses, shit and sunflower seed shells yet though.
- muststopmyths 5y agoBiogas, obviously !
- contravariant 5y agoIf this technology improves enough we should eventually be able to mount the gerbil wheel inside of the Tesla.
- _Microft 5y agoYou have to pull it forward instead of backward but beside that it is not too different from a wind-up car, don't you think? Teslas do not support car-to-car charge transfer for a situation like this, do they? Nice to know that this actually works though.
- devoutsalsa 5y agoCharging stations should be giant hands that pull the car backwards!
- jcims 5y agoThen pinch the wheels and do it again and again until an unholy grating sound comes from under the vehicle.
- devoutsalsa 5y agoI wonder if we'll ever have recharging drones that sense your car is running low, pull ahead of you, and just start towing your car for a ways so you don't even have to stop.
- croon 5y agoI assume this is tongue-in-cheek, but just pulling up close to you and springing out a charging cable arm would be more efficient.
- devoutsalsa 5y agoCould you charge a car while driving it? I guess you can charge a laptop while using it. Why not!
- xeromal 5y agoI don't think current cars can do that but I'm sure could be expanded to
- Retric 5y agoAnd even better just embed some wires in the road and charge everyone at highway speeds. Either ground-level power supply through conductive rails or inductive coils both work with different tradeoffs. https://en.wikipedia.org/wiki/Electric_road https://en.wikipedia.org/wiki/Electric_road
- ErikVandeWater 5y ago> Just embed some wires in the road... No offense but that is the most loaded phrase I've heard this week. That would be a major overhaul of both roads and electric car designs.
- Retric 5y agoSeveral different systems are all at demonstration phases. EX: https://www.theguardian.com/environment/2018/apr/12/worlds-first-electrified-road-for-charging-vehicles-opens-in-sweden https://www.theguardian.com/environment/2018/apr/12/worlds-f... I suspect the hard part is getting every car manufacturer to agree to the same system not designing something that works.
- sokoloff 5y agoIt 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.
- bellyfullofbac 5y agoHah, 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.
- wazoox 5y agoPlus 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.
- raverbashing 5y agoNot 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.
- efraim 5y agoNot true, a rope is fine.
- wazoox 5y agoI 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.
- temp0826 5y agoSo basically teslas are wind-up toys. I wonder how efficient this could be made (I'm picturing something like a dyno)
- croon 5y agoShort answer: not at all. You're just moving the energy expenditure behind lossy generation.
- kingsuper20 5y agoA hamster wheel.
- lapetitejort 5y agoRegenerative braking is so neat. I drove up a steep windy road to go on a hike with my plugin hybrid. On the way down I tried to let gravity do all of the acceleration and regenerative braking do all of the deceleration. At the bottom of the hill I had racked up +3 miles in total. Another fringe benefit is that brake pads wear out slower and produce less pollution.
- unknown_error 5y agoShow HN: lapetitejort goes hiking, discovers perpetual motion
- lapetitejort 5y agoThat would be a neat test. Find a steep hill, preferably as straight as possible, and test how many times an electric car can traverse it before running out of batteries. Would the distance traveled exceed that on a flat road with no generation? By how much? I'm sure someone in San Fran has already tested this.
- cj 5y agoMy intuition would say you'd never have longer range driving up and down a hill compared to driving flat in a straight line (and never braking). I would imagine that at best, you could maybe match the range. If there's any scenario where going up and down a hill would yield more range than driving flat, I'd be very interested in how/why.
- lapetitejort 5y agoYeah, rethinking it, assuming you start and end at the same spot, the milage at the beginning is the max you can achieve, full stop. Simple conservation of energy. So the question becomes, how many miles do you lose at the end?
- dreamcompiler 5y agoGoing up/down at 20 MPH and going flat at 80 MPH might be this scenario. If the velocity difference is big enough, wind resistance will have a bigger impact on range than the thermodynamic inefficiency of regen braking.
- pcarolan 5y agoWe have trains in chicago that reach whiskers up to charging lines above them. Same as the trolley systems in San Francisco. What if every major city to city freeway stretch had these in a lane for electric vehicles?
- dmayle 5y agoI don't know whether or not it is legal, but I have seen an electric car with tram whiskers before. I think I saw it in San Francisco, and I think it was a Prius. Some quick Googling fails to turn it up, though. EDIT Found a link: https://thebolditalic.com/hacked-prius-running-on-muni-power-lines-the-bold-italic-san-francisco-80cdbe55d68e https://thebolditalic.com/hacked-prius-running-on-muni-power...
- athenot 5y agoThat is awesome but the article's date is April 1st 2014.
- dmayle 5y agoBe that as it may, I saw the actual car before I ever saw the article. Maybe it was him, maybe the article is fake, but it inspired someone to try it for real. Either way, I've seen a real life car doing this. EDIT I've found confirmation that the article is an April Fool's joke. I still, however, have seen a car doing this (or at least attempting to do this) on the streets of San Francisco.
- jtbayly 5y agoI question your memory. Lol.
- dmayle 5y agoFair enough... Memory is definitely fallible. In my memory, the car is blue, and what I remember seeing is someone pulling the poles off of the line, but just like we've seen with neural networks, maybe my brain is backfilling the events after having read the story.
- unknown_error 5y agoWhat if you had two Teslas taking turns towing each other at 70 MPH? You could increase the range to (INFINITY*EFFICIENCY)-MATHS! That's a lot of muskjuice.
- moistbar 5y agoWhy stop there? You could get a whole circle of Teslas towing each other and never even have to stop moving!
- mixmastamyk 5y agoThen, have them turn a turbine to generate electricity, qed.
- Jeff_Brown 5y agoObviously a fast tow will generate a faster charge, but does the total amount of energy imparted depend only on distance? Or maybe it actually falls slightly at higher speeds? (The latter is my intuition.)
- rektide 5y agoRandom piece of trivia i found interesting, the dash shows a watthours/mile used view while towing. There's a good bit of variance as the video goes on, but there's a couple periods where it seems to top out at -1200 watthours/mi. 54 mi/h * 1200 w*h / mi = ~65kW watts (87 HP) charging, which is a common rate from superchargers.
- ols 5y agoThe most spectacular example of regenerative braking are trains that are used in Scandinavia, heavily loaded with iron ore that is transported to the coast: "In Scandinavia the Kiruna to Narvik electrified railway carries iron ore on the steeply-graded route from the mines in Kiruna, in the north of Sweden, down to the port of Narvik in Norway to this day. The rail cars are full of thousands of tons of iron ore on the way down to Narvik, and these trains generate large amounts of electricity by regenerative braking, with a maximum recuperative braking force of 750 kN. From Riksgränsen on the national border to the Port of Narvik, the trains use only a fifth of the power they regenerate. The regenerated energy is sufficient to power the empty trains back up to the national border. Any excess energy from the railway is pumped into the power grid to supply homes and businesses in the region, and the railway is a net generator of electricity." (via https://en.wikipedia.org/wiki/Regenerative_brake#Conversion_to_electric_energy:_the_motor_as_a_generator https://en.wikipedia.org/wiki/Regenerative_brake#Conversion_... )
- mechanicalpulse 5y agoThis is fascinating. So they are essentially harvesting the gravitational potential energy of the iron ore at altitude to charge the batteries (and then some) for the cargoless return trip. Outstanding.
- furiousjulius 5y agoReminds me of this dam operation around here that pumps water up to a mountain top reservoir during the day when power is cheap and then lets it go at night when it can generate and sell the electricity for more money. I was always in awe of the lake size battery they created.
- rpmisms 5y agoMaybe this could be applied to water towers? That's a lot of potential energy just sitting there.
- deleted 5y ago
- danboarder 5y agoSo he was getting supercharger speeds (50% battery in about a half hour) which is awesome! The Tesla has its own built in "supercharger" if you can find an alternative way to power it. My idea then is this - could a dyno be modified to be powered and function as competitive to a Tesla supercharger? Basically towing it in-place. It would be rad to see this work! I could imagine connecting it to a geared waterwheel for mechanical power if you lived next to a fast moving river, for example.
- worldsayshi 5y agoThat sounds quite clever! Another potential for low cost infrastructure in remote places.
- ricardobeat 5y agoIt's unlikely that a dyno + all the associated infrastructure would be lower cost than a 150kW charger - they cost ten to twenty thousand dollars apparently.
- TylerE 5y agoNo, it quite explicitly states this is "fast" (e.g. home) charging and NOT even v1 supercharger speeds. "putting back electricity into the batter at a rate of 65 kW - not quite Supercharger speeds, not even V1 or V2 Superchargers that could muster up to 150 kW, but still pretty decent."
- ajross 5y agoThere are no home chargers that can supply 65 kW to anything. That's 270A of 240VAC current (which per most codes would need to be on a 340A circuit), where even large homes have a 200A circuit from the utility for the entire building. Home charging is AC charging, and peaks out around 48A/11kW. The term "fast charging" refers to DC chargers that skip the transformer in the car (which is sized only for 11 kW or so) and do it in the charger device, supplying high voltage DC directly to the battery. And this gets into the dozens and hundreds of kW. Tesla's early superchargers were 75 kW, most CHAdeMO in the US is 50 kW, etc... It's faster than some "fast chargers", yeah.
- rad_gruchalski 5y agoWhat would be great to see is what's the energy balance between tesla towing another tesla at this speed.
- moomin 5y agoI think in the video they said they were getting about a third of the energy consumed, so I'm guessing it would be similar.
- dcanelhas 5y agoThey would clearly have been better off putting a diesel generator on a trailer behind the tesla, for fuel efficiency. 4 gal in 20 minutes the video said? That's about a 160kW generator https://www.hardydiesel.com/resources/diesel-generator-fuel-consumption-chart/ https://www.hardydiesel.com/resources/diesel-generator-fuel-... I wonder how diesel generator + tesla compares to an actual diesel car.
- Smoosh 5y agoI've sometimes wondered if it would be viable to build a "range extender" for electric cars which is basically a generator which is designed to integrate with the vehicle, but can be easily removed. Then people could fit them when they were going on longer trips converting the car to a plug-in serial hybrid. Car dealerships could perhaps rent them out and do the install/removal.
- dreamcompiler 5y agoRange extenders exist. The 2014 BMW i3 offered one as an option. But now that batteries can provide 200+ miles of range there's less need for them and most EV companies have stopped making them. (Of course this hasn't stopped people from building their own.) https://www.autobytel.com/car-ownership/technology/what-is-the-bmw-i3-range-extender-123805/ https://www.autobytel.com/car-ownership/technology/what-is-t...
- ngngngng 5y agoEven for high range cars, this makes so much sense to me. The biggest situation keeping me from getting an electric truck right now is towing something long distance since it kills your range, and often the long distance is way out in the middle of nowhere away from any chargers. This might be oversimplified, but trains have been giant diesel generators powering electric motors for decades now, so why not add diesel generators to cars?
- dreamcompiler 5y ago
- avalys 5y agoThis is interesting to see quantified but not surprising at all - this isn’t really any different than regenerative braking from coasting down a steep hill.
- crackercrews 5y agoThe Mercedes got 5 MPG while towing the Tesla at freeway speeds. [1] 1: https://youtu.be/nILM_DEdBqM?t=336 https://youtu.be/nILM_DEdBqM?t=336
- throwaheyy 5y agoMakes sense. A MB C200 has 135 kW max from the engine, the Tesla’s battery is taking half of that, and losses in the energy transfer would be extra.
- economusty 5y agoI don't think you have much losses in the transfer, the strap is probably efficient. Although they would be extra so you are correct.
- SomeHacker44 5y agoGP almost certainly meant losses in the transfer from mechanical energy to chemical energy by way of the cars motors being used as generators, then charging the batteries.
- throwaway0a5e 5y agoDon't forget the double loss from sending the rotational energy to the ground and back.
- uncoder0 5y agoUnsprung mass always surprises.
- rootusrootus 5y agoI'm surprised it was that good. I get 8 MPG from my F250 when towing a travel trailer that doesn't have the brakes engaged.
- elihu 5y agoThis seems like an interesting solution to the "what to do if my battery runs out in the middle of nowhere" problem. Normally, you'd either have to have to call a tow truck or have someone with a generator come along and recharge. However, towing for awhile (probably at much less than 70 mph for safety reasons) to recharge the battery enough to get to the next town is something that could presumably be done by just about any passing car if you have a tow strap (which could be stored in the EV for such an occasion).
- bin_bash 5y agoOn the Long Way Up they did just this to recharge their Rivians
- lttlrck 5y agoThat is a fantastic show. Rivian and Harley (electric bikes) did great.
- kllrnohj 5y agoOnly if any of those passing cars are gas-powered. If the passing cars are themselves also EVs, then there's both more obvious forms of energy transfer, but also you'll be taking that much range (and more) from the EV doing the towing.
- r00fus 5y agoCost asymmetry - if I had the spare battery capacity (assuming I'm only doing local drives) I'd happily donate it to someone stranded. It's like giving a fiver to fill up emergency gas if they're broke at a gas station.
- elihu 5y agoTransferring energy from one car to the other isn't quite that straightforward, even though it's something that sounds like it ought to be easy. (The simplest thing would be jumper cables, but there's not usually any easily-accessible high voltage terminals, and the batteries might be different voltages anyways. And you'd want to limit curren, and so on....) Maybe if the new Ford F150's 220-volt outlet becomes a common feature, then charging from one car to anther will be easier (though very slow). I think the main towing advantage a typical ICE car would have over an EV with extra battery capacity is the ability to shift into 1st or 2nd gear. It's not really an intrinsic property of EVs that they can't have transmissions, but so far the major manufacturers have decided it's not worth it. (The Taycan is a notable exception.)
- worldsayshi 5y agoCouldn't we use smart kites that would fly around hooking up to your car as sails whenever there's a lot of wind in an area with open skies? Get towed, charge a bit and/or save battery. The car automatically sends some fee payment as a thanks. Requires a lot of smart infrastructure that we don't have but it seems like one of those things that should be doable once we've figured out autonomous driving...
- recursive 5y agoHow often will someone be driving slower than the wind? Almost never.
- worldsayshi 5y agoYou can sail faster than the wind when you push against a medium though. Veritasium has a very relevant interesting episode on this: https://youtu.be/jyQwgBAaBag https://youtu.be/jyQwgBAaBag Although I agree it would be challenging to get any significant speed from it.
- recursive 5y agoLove that episode, but I don't think this would work at all. Attaching a kite to that vehicle would only slow it down.
- nimbius 5y agoJust a little conjecture here, but i find the whole experiment fascinating. A tesla model S is around 5000 pounds. not the lightest car on the road by any standard...but towing it behind a consumer Ford F150 will drag the mileage of the truck to 14MPG. not too shabby compared to your long-haul tractor trailers that get about 6...but thats the free rolling weight of the vehicle, not its weight with regenerative braking turned on. id be very curious to know what the final hitch and tow weights are respectively. from what i can tell, a supercharger will get you charged in about an hour. so...70 miles? most trucks cant maintain that speed in hills or corners, so unless you live in nebraska, youll be on the road a lot longer than an hour. other states might not let you hit 70 at all....can it be done at lower speeds? given the wind conditions on any given day, you might not be able to safely maintain a 70mph tow. other states (california) impose tow restrictions on just how fast you can go. RV owners probably wont buy a tesla based on this knowledge but id love to see more data from this kind of testing...could the energy from the regeneration be used to charge RV batteries too? can this regenerative system be applied to trucks to power heaters and air conditioners during layovers and downtime?
- Brainmulch 5y agoI think you have just described something like a traditional or plug-in hybrid that recovers energy that would be wasted under braking or puts the ICE under additional load to keep the specific fuel consumption as low as possible
- throwaway0a5e 5y ago>A Tesla model S is around 5000 pounds A whole host of 90s pickups are ~5000lb depending on how they're spec'd out. The Model S is fat. But so are a lot of other modern cars so whatever. 5k isn't that much at the end of the day though. Perfectly within the bounds of what a scrapper or farmer will tow with a compact truck. >not too shabby compared to your long-haul tractor trailers that get about 6 Heavy trucks punch an 8'6" by 13'6" hole in the air. The comparison is comical.
- millerm 5y agoBut it’s not just 5k lbs free rolling. The regenerative brakes are an opposing force and increasing the load. So, it could be equivalent to 10k lbs. I have no idea how to calculate that though.
- nixpulvis 5y agoA friend of mine recommended I watch this video after I was asking him about the limits of these things: https://www.youtube.com/watch?v=oJL9MasBFvM&ab_channel=EngineeringExplained https://www.youtube.com/watch?v=oJL9MasBFvM&ab_channel=Engin... I attempted to summarize below: "ah yes, it's because the batteries take up a vastly large percentage of the vehicles weight. For towing (hauling?) this is a critical figure, whereas it generally doesn't matter for a passenger car. That said, IIUC, this is equivalent to range, it's just that many gas cars choose to sell lower percentage weight tanks since they go plenty far already, and that way you accelerate faster." Sorry for the strange comment style.
- jborichevskiy 5y agoIsn't this just transferring energy from the car towing to the Tesla itself? My understanding is this production of power induces some friction, that otherwise would've been closer to neutral. In other words, if the wheels were completely free to spin, would not the towing car require less power to tow? Or is my understanding of this off? Physics was a long time ago
- Obi_Juan_Kenobi 5y agoYes, there's no claim of free energy or perpetual motion here. The author even discusses approximately how efficient the charging is in the video.
- jborichevskiy 5y agoOh yeah I guess I worded it wrong; I wasn't imagining free energy. Framing it as an efficiency question is more clear, thanks. In other words, this way of converting $natural_resource to Tesla battery level is less efficient than say, plugging into a power grid as there's an extra conversion step (ground to brakes/ambient friction).
- zelon88 5y agoThis technology was used as early as WW1 on diesel-electric submarines. The primary electric drive motors could be driven by the diesel engines to recharge the batteries while on the surface.
- theHIDninja 5y agoI wonder how much less efficient this is than charging it through normal means. Can someone more intelligent than me run the numbers on that?
- mancerayder 5y agoThe Model 3 manual says not to tow for long distances and to use a flatbed truck for that.
- raspberry-eye 5y agoFinally, a use for the hyperloop
- raspberry-eye 5y agoE we hee as t if. The hyperloop was slow but free.
- raspberry-eye 5y agoVacuum at 70mph fir charging to location away from the loop
- eurasiantiger 5y agoIf we’re doing this, cars could be spring-driven.
- pugworthy 5y agoMy daughter has a small Schoolie (converted school bus) she lives in, as well as a tiny Fiat 500e for day driving. We've always wondered if there wasn't some way to tow it effectively, and allow it to charge at the same time. You could turn on regen if you needed a charge, or turn it off and get better mileage with the bus.
- mlacks 5y agowould it be possible to have a "treadmill" at supercharger/ gas stations to simulate this experiment?
- joelbondurant 5y agoTesla's coal powered cars are ridiculous.
- ubermonkey 5y agoI wondered if other electrics could do this when I saw it as a touted feature of the Rivian electric pickups in Ewan MacGregor's The Long Way Up show.
- jiveturkey 5y ago… by consuming the power provided by the tow vehicle
- sunshineforever 5y agoSo I'm thinking, might it be easier in some instances to build spinning wheels for the Teslas to sit on top of in order to charge them?