Light Year One
newdawn.lightyear.one
newdawn.lightyear.one
In-wheel motors are interesting. That changes the dynamics of the vehicle by adding what we mech-e's call "unsprung mass". Vehicle handling takes a huge hit. There's a reason there are no cars on the market with in-wheel motors at present. Additionally, you're putting expensive components in a place where they can be more easily damaged. There's also the fact that in-wheel motors can be very dangerous if there's a failure of the control system. Since there are no cars on the road like this, I'm wondering if the team truly has the expertise to tackle these issues.
But I'm not trying to be a cynic. I spent 8 years as a mechanical engineer designing hybrid and electric cars; these are simply challenges that need to be engineered around. This is a cool car, and I hope it makes it to market. We need more of this.
Lightyear's claim is that putting the motors in the wheels improves control. Could it be that unsprung mass is reduced by negating the axle?
Note a distinction between "control" and "handling". Four in-wheel motors will have better control but worse handling. Traction control can be applied to each individual motor, improving control in some cases, but on bumpy or rough roads the car will experience worse handling, as the wheels will "hop" off the surface more.
Imagine a car driving over a speed bump a little too fast. In a standard suspension, the wheels are light enough that the suspension pushes them back down to the road surface very quickly at the far end of the bump. If there is more unsprung mass, however, the wheels have more inertia, and so the suspension is not able to push the wheels down to the surface as quickly. Now imagine that same car taking a fast turn on an uneven road surface. If the wheels aren't pressed down to the surface after coming up off a bump, that wheel will lose traction, and traction is required for sticking the turn. In that case, no amount of traction control can make up for the loss of friction.
Apparently, the motor on the Tesla Model S is 70 lbs ( https://chargedevs.com/newswire/elon-musk-cooling-not-power-... ). With individualized motors, each would likely be less than this. Combined with the battery weight attached to the car's chassis, I would expect this to result in a lower ratio of unsprung mass to sprung, and thus better handling than typical on a non-battery car.
Is that their main competition, though?
This is not a feature of in-wheel motors, but individual motors. And not even much of that, because you can apply the brakes to shift power through the differential to the other wheel (a technique modern all-wheel drive cars including Teslas use for traction control). Is having a motor for each wheel really a huge improvement over that? Maybe latency can be improved a little?
Parts of the team behind it was part of a university challenge team called "Solar Challenge" and won it a few times. They drove that car through Australia the fastest without fuel of charging. That car was ugly and uncomfortable though.
All that said, I strongly doubt they'll ever be able to spin up production. I bet that everybody's best case scenario is they produce a few cars that don't totally suck and kinda/sorta make good on the efficiency / usability claims, and then some automotive bigco acquires them.
Do you know how the company is financed? What price they're aiming to hit? Have they done market research to figure out whether people actually want a probably very expensive car that is efficient, but not sporty? Does anyone actually need that range (I know I don't)?
The idea that a car could charge itself from integrated solar panels enough to cover the distance of the average daily driving is interesting but you would think Tesla thought about this and decided the math didn't work or they would already be doing it. They are in the solar power business as well after all.
Tesla has done great work in exploring the space of how you make an EV that impresses Top Gear viewers.
I'm also interested in seeing similar progress for people who just want to get from A to B cheaply and efficiently and sadly few of the existing car makers seem to be taking EVs seriously yet. I've often thought that a different set of assumptions (e.g. not caring about topspeed) might lead to a better overall car, sounds like they are exploring this area.
Especially if you want to, you know, park in a garage.
This is an idea well ahead of its time. When solar cells become REALLY cheap after the current growth curve in a decade or so, it will be an afterthought to put on solar vs paint.
They say that at 3.7KW it gains range at 35km/h, and from solar it gains range at 12km/h. This means that they expect to get 1.23KW of power from their solar cells. Top theoretical efficiency possible for any solar cell is about 33% (Shockley-Queisser limit), most efficient you can buy today is 22%. So that means they expect 5.59KW of sun energy to fall on the car per square meter. A typical car is 4.5x2 meters. Let's assume they tile the whole damn thing with highest efficiency cells except the windshield (1x2m) They then have 7m^2, so they expect solar energy to provide 799W/m^2. And it is true, sunlight reaching earth is about 1KW/m^2 at the equator in noon, but that is in perfect conditions and just there, and when cell is perfectly aimed at the sun. The car will not tilt, and some days there are clouds or haze, and we do not all live at the equator. Also, in fact, not the entire car can be tiled with solar cells, and dirt exists, especially on the road.
So the numbers they promise are pretty much at the very limit of theoretical possibility in ideal conditions, and not even remotely likely to be hit in real life.
> In fact, our solar cells provide about 20% more energy than traditional ones.
The numbers they provide are best-case. There's also this:
> Someone driving the national average of 20,000 km/year in the cloudy Netherlands would get about 40% of their mileage from solar energy.
They've clearly thought about this. I agree that solar roof on a car, as it stands today, is a gimmick at best, but the fact that your envelope calculation actually _confirms_ that solar charging is possible is enough for me to not dismiss them out of hand. This isn't utter bunk, at very least.
Edit to add: we're probably doing ourselves a disservice thinking about solar charging in terms of range; instead, consider that parking the car in the sun for a day could offset the cost of running climate control for the next 3-4 days. Someone needs to try it, sometime, so I'm glad they are.
Solar is DC. for instance Tesla powerwall is 97% efficiency for DC/DC conversion for charging its battery. So you need basically 1kW of solar to produce the needed energy to drive 12km (per hour). I think you are off by at least a factor of 3.
edit: at 20% solar efficiency that would require 5m^2.
Also, if I do the math on their AC charging. 35km/h gained --> 2905Wh energy. Standard 230AC, 16 amps is 3680W. So I guess the number there is also correct? Take about 85% efficiency, then you have 3000Wh in one hour from 230V AC
Actual figure given on website is 5m2 of panels on car. Assume 1Kw per m2 of sun power (near equator, no cloud, midday) @ 22% conversion efficiency gives 1.1kw electrical output from panels.
So one needs 5.59KW sun power input for 1.1kw output.
Still, something's fishy about this vehicle.
[0]https://www.ise.fraunhofer.de/en/press-media/press-releases/... [1]https://www.ise.fraunhofer.de/en/press-media/press-releases/... [2]https://www.oxfordpv.com/news/oxford-pv-perovskite-solar-cel...
On a luxury car like this, area is constrained and money is no object, so it may make sense to use otherwise prohibitively expensive cells to win a few extra percent efficiency. Similarly, such multi-junction cells are used on spacecraft, where the lower mass per watt makes it worthwhile.
Turns out it would add only a trivial amount of energy, and thus is just a gimmick.
>Although the energy from the solar panel might seem like a large value, it's only 2 percent of the total battery energy.
https://www.wired.com/story/could-tesla-power-its-electric-t...
But at the moment, panels are expensive and would add weight, which offsets much of the benefit.
I do want such ideas to succeed, but this is about as credible as a cryptocurrency whitepaper.
It's definitely a gimmick, but I'm not willing to dismiss them out-of-hand. I've designed and built several hybrid and electric cars with teams 1/4 of this company's size, so I don't take issue with the design or their ability to build 1 or 100 units, but rather their ability to actually bring this thing to market and be successful.
https://www.cbc.ca/news/canada/toronto/toronto-engineering-s...
Car is extremely light (you can pick it up), spindly, aerodynamic, has none of the roadworthy safety features, uses all energy for driving (no AC, headlights, etc.). These compete in the World Solar Challenge and manage a good speed (50 mph) over long distances powered by the sun. This is a good example of what is possible.
There is no way that a "traditional" car, carrying five, spare tire, safety features, headlights, bluetooth, cup holders, with apparently less solar surface area, is going to manage any sort of respectable distance or velocity powered by the sun alone.
Lesson for web designers: do not do this. Now we are talking about a silly web feature while we are supposed to look at whatever message your website is trying to convey.
edit my bad this is how much extra it would charge a day. Seems like it could hold an 800km charge which is incredible.
Opinion: Tesla should buy them.
That still has to be mounted on something, but that something easily could be the car’s structure (and it is. The site says ”The roof and hood of Lightyear One comprise of five square meters of integrated solar cells within safety glass”)
But yes, the power budget still will be small.