[HN Gopher] Towing a Tesla at 70 MPH replenishes battery at fast... ___________________________________________________________________ Towing a Tesla at 70 MPH replenishes battery at fast charger rates Author : danboarder Score : 95 points Date : 2021-06-21 13:26 UTC (9 hours ago) (HTM) web link (insideevs.com) (TXT) w3m dump (insideevs.com) | _Microft wrote: | You 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 wrote: | Charging stations should be giant hands that pull the car | backwards! | avalys wrote: | This 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. | devoutsalsa wrote: | I 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 wrote: | I 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 wrote: | Could you charge a car while driving it? I guess you can | charge a laptop while using it. Why not! | xeromal wrote: | I don't think current cars can do that but I'm sure could | be expanded to | Retric wrote: | And 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 | ErikVandeWater wrote: | > 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 wrote: | Several different systems are all at demonstration | phases. EX: 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. | elihu wrote: | Sure, but it would be worth it. | | The cost is that you'd have to re-engineer maybe ten or | twenty percent of major freeways and interstates (like | have two miles of charging per every ten to twenty miles | of regular road), and you'd need to establish a standard | for trucks and passenger vehicles and get automakers to | adopt it. (Or make it simple enough that it can be added | as an aftermarket kit.) You'd also need to install more | electrical generation capacity. (Fortunately, charging | cars while they're driving shifts most of the charging | from nighttime to daytime, when solar power can be used | for this purpose.) | | The benefit is that you could reduce long-haul trucking | fuel consumption to near zero and reduce the need for EVs | to have heavy, expensive 200-mile-or-more-range | batteries. | rsynnott wrote: | A somewhat more practical approach: | https://www.theverge.com/2019/5/9/18538030/germany- | ehighway-... | elihu wrote: | Overhead lines are probably the simplest and cheapest | option, but the downside is that you're basically limited | to trucks only due to the cable height, unless you also | have a passenger car-only lane with lower cables. | | There's a test in Sweden that uses power rails embedded | under the road surface. I like that approach because it's | more versatile and looks better, but on the other hand | it's also more expensive. | contravariant wrote: | Everything old is new again I suppose. | dronechariots wrote: | At that point, why not just have drone chariots that pull you | the whole way | croon wrote: | New headline: "Tesla reaches destination without expending | any energy!" | unknown_error wrote: | Add a few string lights and you have a poor man's Helios | SketchySeaBeast wrote: | ... And we've reinvented pod-racing. | rini17 wrote: | Or use horses or mules. Would be a sight to behold :) | BeefWellington wrote: | Or you could have dyno-based chargers that work like automated | car washes. Pull in to a stall, guided onto the drums, put in | gear, go for a coffee. | | Cons: | | - Less efficient than using an actual electrical cable. | | - Requires larger infrastructure space. | | Pros: | | - Could work with any brand that has regenerative braking. | | - Could be adapted into existing automated car washes as a | premium feature. | Jeff_Brown wrote: | Obviously 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.) | sokoloff wrote: | 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. | bellyfullofbac wrote: | 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. | dreamcompiler wrote: | 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. | marc__1 wrote: | @Peloton, here is your next big idea | bellyfullofbac wrote: | Hah, they should integrate the bike into the car and make | the modern Flintstones car. | wazoox wrote: | 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. | raverbashing wrote: | 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. | efraim wrote: | Not true, a rope is fine. | deeblering4 wrote: | Until the tow truck hits the brakes... | SketchySeaBeast wrote: | First day of statics - you can't push a rope. | quercusa wrote: | I was once involved in towing a car using a partially- | inflated water bed as a 'bumper'. We got there! | wazoox wrote: | 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. | detaro wrote: | 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. | Retric wrote: | 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. | toomuchtodo wrote: | 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). | baybal2 wrote: | Teslas have no resistor banks? | | A great omission. | dreamcompiler wrote: | 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. | [deleted] | meatmanek wrote: | 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. | nwiswell wrote: | 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. | dreamcompiler wrote: | 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? | bin_bash wrote: | that's correct. You don't get one pedal braking if it's | not charging. | Dylan16807 wrote: | I don't think the brake pedal was being used in this test, | though. | toomuchtodo wrote: | 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. | Dylan16807 wrote: | Sure, so the car stops charging and still won't | waste/damage its brakes in the tow. | sokoloff wrote: | 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. | Retric wrote: | 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. | sokoloff wrote: | 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. | crackercrews wrote: | The Mercedes got 5 MPG while towing the Tesla at freeway speeds. | [1] | | 1: https://youtu.be/nILM_DEdBqM?t=336 | temp0826 wrote: | So basically teslas are wind-up toys. | | I wonder how efficient this could be made (I'm picturing | something like a dyno) | croon wrote: | Short answer: not at all. You're just moving the energy | expenditure behind lossy generation. | kingsuper20 wrote: | A hamster wheel. | ols wrote: | The 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 Riksgransen 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_... ) | throwawayboise wrote: | What does the equation look like when you subtract the energy | used in the actual mining, though? | ols wrote: | On the other hand it would be nice to count in that the iron | ore gains value when it's moved from inside the mine to the | port. | mechanicalpulse wrote: | This 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 wrote: | Reminds 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. | dreamcompiler wrote: | Pumped hydro is one of the cheapest ways to store | electricity iff you have the topography available to create | the uphill lake and plenty of water available to compensate | for evaporation. | rpmisms wrote: | Maybe this could be applied to water towers? That's a lot | of potential energy just sitting there. | [deleted] | dharmab wrote: | Water towers are already used that way- water is pumped | in during off-peak time and used during peak time. | cobaltoxide wrote: | Not enough volume. | | And you have to maintain water in the tower in order to | keep the water distribution system pressurized. | sigstoat wrote: | pumped storage systems are so large as to be geographic | features. | | there isn't much energy in a water tower. and that water | is already doing work, pressurizing the water system. | Guvante wrote: | So I did the math and the average water tower holds | something like 1/2 kWh worth of power. (50m tall, storage | of 1m gallons, efficiency of 90%) | | Hydro power storage is fantastic but needs truly | ridiculous amounts of water and height deltas to make | sense. | avalys wrote: | You're telling me I could fill a typical water tower in 1 | hour with a 500 W pump running off a kitchen outlet? | Aperocky wrote: | You probably made a mistake somewhere. | | 3.8Mg * G * 50m ~ 1700M Joules which is about 500kWh. | NemuriBaku wrote: | I suspect the k in kWh leads to the occasional factor of | 1000 error. | hnuser123456 wrote: | https://www.wolframalpha.com/input/?i=gravitational+poten | tia... | | I got 450 kWh? Maybe you meant 1/2 MWh | FridayoLeary wrote: | The heavy iron ore is essentially a large battery storing | gravitational energy. In a way it's just another natural energy | source. Maybe in the future clean power can be generated from | pulling down mountains. | mdeeks wrote: | Apparently there is already the concept of rail train | batteries: https://www.vox.com/2016/4/28/11524958/energy- | storage-rail | | You run the trains up the hill when energy is cheap or, for | example, when the sun is out and solar works. Then when you | need it, you run the trains down hill to generate | electricity. Similar to pumped hydro where they do the same | by pumping water up hill and then draining it downhill later. | Super cool! | sigstoat wrote: | > Maybe in the future clean power can be generated from | pulling down mountains. | | it takes a lot of power to dismantle mountains and load them | onto trains. and folks get real grumpy about mining | operations leveling off mountains. | perihelions wrote: | >Maybe in the future clean power can be generated from | pulling down mountains. | | With added bonus efficiencies from combusting the coal that | fortuitously falls out! | lwansbrough wrote: | This idea is sort of being explored already: | https://www.youtube.com/watch?v=itbwXMMkBQw | | There's other ways of doing this too. Rolling a ball up a | hill, inflating a balloon under water, etc. | [deleted] | tobltobs wrote: | The same as a quarry truck in Switzerland: | https://www.autoblog.com/2019/08/26/edumper-electric-mining-... | Schweigi wrote: | Which has a nearly infinitive range because because of how | the quarry is set-up! In a way the perfect use case for | electrification. The truck is able to drive anywhere and much | more flexible - e.g. compared to a conveyor belt or cable car | solution. | brightball wrote: | I've seen something similar to this with large dump trucks made | for hauling loads down mountains. They generate so much power | fully loaded on the way down that they can make the trip all | the way back up. | elihu wrote: | This 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 wrote: | On the Long Way Up they did just this to recharge their Rivians | dcanelhas wrote: | They 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-... | | I wonder how diesel generator + tesla compares to an actual | diesel car. | Smoosh wrote: | I'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. | rad_gruchalski wrote: | What would be great to see is what's the energy balance between | tesla towing another tesla at this speed. | moomin wrote: | I think in the video they said they were getting about a third | of the energy consumed, so I'm guessing it would be similar. | danboarder wrote: | So 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 wrote: | That sounds quite clever! Another potential for low cost | infrastructure in remote places. | lapetitejort wrote: | Regenerative 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 wrote: | Show HN: lapetitejort goes hiking, discovers perpetual motion | lapetitejort wrote: | That 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 wrote: | My 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 wrote: | Yeah, 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 wrote: | Going 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. | Workaccount2 wrote: | In theory they would be identical, but in practice a flat | road would be better. There are more real world | inefficiencies with going up and down a hill. | codeulike wrote: | _Would the distance traveled exceed that on a flat road | with no generation?_ | | No. Climbing the hill the car uses extra energy (compared | to a flat road) because its fighting gravity. On the way | back down the hill regen will recover some of that gravity- | fighting energy but nowhere near all of it. | hourislate wrote: | This scenario is a little different than a car but a | Swiss company is experimenting with a Komatsu Dump Truck | that basically recharges its battery using regen braking | on it's trip down so it has enough power for the trip up. | It actually generates a surplus of an extra 10kwh because | the truck is carrying a full load down. | | https://phys.org/news/2017-09-e-dumper-world-largest- | electri... | monkeybutton wrote: | And going up it is empty. Its basically exploiting the | fact that rocks at the top of a hill have higher | potential energy than at the bottom. If you charged the | trucks with wind/solar at peak times and used them to | carry the rocks back uphill you could have yourself a | very convoluted and mechanically fraught battery! | codeulike wrote: | Like Pumped Storage Hydroelectricity | | https://en.wikipedia.org/wiki/Pumped- | storage_hydroelectricit... | UncleOxidant wrote: | A good visual demonstration of entropy. Heat death occurs | when all of the mountains have been leveled and there are | no altitude differences to exploit. | EvanAnderson wrote: | That's excellent! I'm stealing that. | unknown_error wrote: | That's actually pretty cool. It's kinda like a dam... | harnessing potential energy stored by geologic processes | and turning that into power? I'm sure there's some fancy | physics word for it that I don't know. | ineedasername wrote: | That's just pseudoscience: The earth is flat so there's no | such thing as going up hills. | seanmcdirmid wrote: | +3 miles hopefully didn't include the energy spent going up, | or the law of energy conservation would have been broken. | bin_bash wrote: | Not necessarily. The range is a function of energy over | rate of consumption. It's possible the car changed the | denominator giving it a further range estimate with less | total energy remaining. | TheSoftwareGuy wrote: | I think the wind at his back is key here. His car was | acting like a wind turbine | croon wrote: | I think OP meant winding and not windy, but even if not, | Teslas (and any other car) are designed to be | aerodynamic, not the opposite, so it's quite impossible | to yield more energy than it cost in that scenario, even | ignoring motor efficiency, regenerative braking | efficiency, and every other real world inefficiency. | underwater wrote: | Windy is a perfectly valid descriptive word for a | twisting road. | tomjakubowski wrote: | the confusion in this thread is that windy, as written, | could mean there's lots of wind (said "win-dee") or lots | of bends (or "winds", said "whine-dee"). "winding" is | less ambiguous | wolverine876 wrote: | > Teslas (and any other car) are designed to be | aerodynamic | | Why not design them to be aerodynamic for headwinds, and | maximize wind-resistance for tailwinds? I wonder how much | energy would be gained. | sva_ wrote: | I imagine there might also be an effect in play, in which | the available miles are calculated using the energy used in | the past x miles. Although it should usually take a fairly | long distance to change that approximation... I think. | Maybe something about using negative energy though | regenerative braking skews the approximation. | teeray wrote: | He used a portal at the top and bottom of the hill and has | now solved the world's energy problems, including powering | the portals | HWR_14 wrote: | +3 miles is precise enough it could easily be measurement | errors | EvanAnderson wrote: | Maybe he picked up several large people who were already at | the top. | selimthegrim wrote: | Energy trolls? | unknown_error wrote: | Maybe lapetitejort had better lawyers. | SLWW wrote: | probably the first time a comment on HN has made me | laugh. | | I hope the prosecutor has enough leverage with the court! | Justice truly is blind! | asdff wrote: | You can get this sort of benefit with a gas car with a manual | transmission too. Engine braking uses no gas, its just your | wheels turning your pistons and the friction from all of that | slows the car down. Most of the time I only hit the brakes to | go from 5mph-0mph in a manual car thanks to this. | oh_sigh wrote: | +3 miles electric, -20 miles gas (or something like that). | pcarolan wrote: | We 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? | wolverine876 wrote: | Why not wireless power? I would guess that it's highly | inefficient, and goodness knows the radiation levels that would | have to be broadcast throughout the city to charge all the | cars, but imagine if everything you had was charged | automatically in the city. | ErikVandeWater wrote: | Are all the cars going to reach up 13 feet in the air to the | charging lines? That would be a very tough sell. Not to mention | the increased danger of live power lines coming down in an | accident. | | Also, how would lane changing work? Do they have to decouple | from one set of power lines and connect to another? | pcarolan wrote: | Why not? We do it safely in busy urban areas already. As for | changing lanes, even the most basic autopilots could solve | the lane changing problem. Also, making connection can help | steer the car and coordinate with other cars in the charging | lane. | jeofken wrote: | Volvo did a trial of this. Not sure how it ended up. | | https://www.volvogroup.com/en/news-and-media/news/2018/sep/v... | rektide wrote: | Seems like a lot of physical infrastructure spread out over a | lot of area for little gain. Little gain because it doesn't | feel like charging at fixed stations is so bad, and it's not | something folks need to do that often. There's other challenges | too. You'd also need to build some system for billing, such | that people don't start to steal power. Do we trust the cars to | meter themselves? Or do we try to have the line monitor who is | using how much power continuously? | | Personally i more imagine something like this video, except | instead of physically towing a car to run it's generator, the | "tow" vehicle is merely a truck with a lot of batteries, | battery-powered charger (easy), and charge plug at the end of a | boom arm. Folks can summon a on-the-go charger & it follows | them around for ~30 minutes & charges them. | | I like the big-dream nature of your ask, how it seeks to adapt | the infrastructure of the road to the new power modality. It | seems dauntingly expensive, but it's certainly going to be more | power-effective & material-effective than battery-charger- | trucks are. | pcarolan wrote: | The other advantage is coordination and self driving. You | could pretty much get in the charging lane, go to sleep and | wake up in chicago. The whiskers can provide steering and | other vehicle coordination if you think of them as power + | data. | rektide wrote: | And you can build special roads that only your model of | cars can drive on, with your model of cpu brains. And maybe | get some government grants to build it all. | wolverine876 wrote: | > Little gain because it doesn't feel like charging at fixed | stations is so bad | | I think people would like very much never having to charge | their cars as long as they remain in the city. | dmayle wrote: | I 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... | athenot wrote: | That is awesome but the article's date is _April 1st_ 2014. | dmayle wrote: | Be 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. | worldsayshi wrote: | Couldn'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... | unknown_error wrote: | What 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 wrote: | Why stop there? You could get a whole circle of Teslas towing | each other and never even have to stop moving! | mixmastamyk wrote: | Then, have them turn a turbine to generate electricity, qed. | Simulacra wrote: | What 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 wrote: | I 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 | stavros wrote: | Is the argument that if you could have salted the tail you | could have just caught the bird? | dhosek wrote: | You 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 wrote: | What 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 wrote: | You'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. | hughrr wrote: | I 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 wrote: | Biogas, obviously ! | contravariant wrote: | If this technology improves enough we should eventually be | able to mount the gerbil wheel inside of the Tesla. | rektide wrote: | Random piece of trivia i found interesting, the dash shows a watt | _hours /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 | watt_hours/mi. 54 mi/h * 1200 w*h / mi = ~65kW watts (87 HP) | charging, which is a common rate from superchargers. ___________________________________________________________________ (page generated 2021-06-21 23:00 UTC)