[HN Gopher] Towing a Tesla at 70 MPH replenishes battery at fast...
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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.
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