DIY 1,500W solar power electric bike (2022)
electrek.co
electrek.co
He told me his biggest build-regret was the solar panels. Mounting the solar panels on the bike makes everything much more complicated—which means it's more expensive and more delicate. And even if it doesn't shake itself apart, you're constantly thinking about where and how you're parking it.
The right solution for solar powered biking is to keep the solar panels off the bike, fixed in place, facing the right direction. Then you can use lots of cheap, heavy panels, and just plug the damn bike in when you get home.
[1] for example: https://www.amazon.com/Flexible-Monocrystalline-Bendable-Sem...
It costs $90, not including the protection circuitry.
Even if you pay a lot for electricity (e.g. $0.35 per kWh, like in PG&E service regions), you'd need to be drawing 100W for 7 hours per day, for 365 days, before you break even.
I guess realistically you're more likely to break even after 2 years? Do these small panels 'wear out' over time, or will they work for several years?
You can reasonably expect it to lose less than 1% of original efficiency a year, so they should last decades.
Note that none of the above is about saving money. Other than indirectly because it lets you use a bike for trips that otherwise would require a car, and cars cost a lot more money to own. The above are also uses that I have for an ebike (I don't have one, but those are potential uses making me interested in one), and solar would help make it work out.
This bike seems to have been designed to carry kids at the bike, not haul stuff.
I own this bike: it's very good at carrying kids, pretty good at carrying stuff, and exceptionally good value. Rad has been shrinking the back wheel to lower cargo position as iterations progress, which is nice.
I've owned a RadCity before and it wasn't shitty at all. The dang thing is still running after 7k miles of rough treatment and crashes. The only problem I really had is with the spoke pattern on the drive wheels. They used way too thick spokes that didn't like being bent at such a sharp angle.
Not quite what I expected when I read the title.
Btw, the panel is 50W, and I assume the battery is stock, 672 Wh. That's 14+ hours of best-case sunlight to recharge fully. I wonder how practical is it.
My personal preferred way to do this would be to have a stationary battery to charge up, and better solar panel positioning like you say, but that costs a bit more for that stationary battery. And if the only thing that battery/solar setup is used for is charging the bike, and you don't actually need more power then all that extra power is just gonna go to waste.
Still a fun project though, and not something I built to make a return on.
Modern fridges are often inverter drive, so should be easier to incorporate a DC power source. And they generally run all the time because they do variable-frequency drive.
Best part, it keeps working during power outages. Extra points for putting on a USB charging port (only works during the day, but still!).
If you leave the bike out in the sun all day, you can probably add 10-15 miles of range, which would be practical for some people (not everyone of course, but for many people, an e-bike wouldn't be practical even with infinite range).
But yeah 7-10mi realistically in most of the US or 5mi in the winter. That's not terrible, but it does require pretty perfect alignment and no shaddowing.
In a pedelec after a certain point you and the battery are working together to maintain speed and it really doesn't take much battery. But there are so many variables that it's hard to talk about it meaningfully.
Storing the bike outdoors continuously in the sun, wears on the condition considerably faster than indoors.
Having the solar panel attached makes for "all in one" articles, but seems rather limited on practicality for most people.
Then you can bring your bike inside, in the shade, etc. — not having to always find sunlight to park in.
The only way bringing the solar panel with the bike makes sense is a multi-day ride. But as is being pointed out, you're going to be spending a lot more time sunbathing rather than biking under power.
The cost figures in this article about [rooftop,] wind do not take into account latest gen [Dyneema] ultralight rooftop solar:
"Rooftop wind energy innovation claims 50% more energy than solar at same cost" (2022) https://pv-magazine-usa.com/2022/10/14/rooftop-wind-energy-i...
> The scalable, “#motionless” #WindEnergy unit can produce 50% more energy than rooftop solar at the same cost, said the company.
> The technology leverages aerodynamics similar to #airfoils in a race car to capture and amplify each building’s airflow. The unit requires about 10% of the space required by solar panels and generates round-the-clock energy. Aeromine said unlike conventional wind turbines that are noisy, visually intrusive, and dangerous to migratory birds, the patented system is motionless and virtually silent.
> An #Aeromine system typically consists of 20 to 40 units installed on the edge of a building facing the predominant wind direction. The company said the unit can minimize energy storage capacity needed to meet a building’s energy needs, producing energy in all weather conditions. With a small footprint on the roof, the unit can be combined with rooftop solar, providing a new tool in the toolkit for decarbonization and energy independence.
"18 Times More Power: MIT Researchers Have Developed Ultrathin Lightweight Solar Cells" (2022) https://scitechdaily.com/18-times-more-power-mit-researchers... :
> When they tested the device, the MIT researchers found it could generate 730 watts of power per kilogram when freestanding and about 370 watts-per-kilogram if deployed on the high-strength Dyneema fabric, which is about 18 times more power-per-kilogram than conventional solar cells.
> “A typical rooftop solar installation in Massachusetts is about 8,000 watts. To generate that same amount of power, our fabric photovoltaics would only add about 20 kilograms (44 pounds) to the roof of a house,” he says.
> They also tested the durability of their devices and found that, even after rolling and unrolling a fabric solar panel more than 500 times, the cells still retained more than 90 percent of their initial power generation capabilities.
E.g. Hyperlite Mountain Gear sells Dyneema ultralight backpacking packs and coats. There are Dyneema Patch Kits that work for various types of gear.
Wise to look at Ultralight backpacking gear before buying regular camping gear. Solarcore Aerogel is warm and light and also in encased in PVA foam rubber which is like a new wet suit. https://twitter.com/westurner/status/1600820322567041024 Kayaking bags are waterproof, but are there yet Dyneema ones?
730-370 watts/kilogram is the number to beat (for DIY electric bicycle applications)
And rooftop wind is competitive (for charging offline batteries)
Presumably, bicycling is like ultralight hiking: wHr/kg is the or a limit https://en.wikipedia.org/wiki/Kilowatt-hour
A pedaling electric bicycler could tow a solar wagon, eh
I guess the sensible way would be just having bigger, fold down solar panel array and to deploy it where you stop.
Things may work out if you plan on having a stationary camp somewhere remote.
There are no easy answers.
Also, the electronics are mounted out in the open and on top of a small bit of wood, that works well in the lab but if you're going to be biking and end up being rained on it may well cause issues, just using splash proof connectors isn't enough, you need to protect the electronics from the elements by eliminating direct contact with the elements. Much like in a car: all of the connectors under the hood are waterproof and they are under the hood, not out in the weather.
That said, it's a neat idea.
Source: I cushion my robots this way, haven't gotten to the ebike yet.
On the whole it isn't perfect but good enough for many years, I've run this setup for a year now and have once (at 5K km) inspected the wiring and the battery welds and everything seems to be holding up quite well. Things to be careful with: overpressuring the tires would reduce the amount of shock absorbing capacity quite a bit (and is definitely not recommended with tires this wide anyway), the rolling resistance of these is fairly high but that is just how they are designed. Then, obviously there is bumping in to things and falling at speed, which fortunately hasn't happened. But if it did I would immediately consider the battery pack a write-off in spite of being super well protected. I've done about 10K on it now and when it hits 20 I'll take the whole thing apart to see if there is any wear that is hidden from view. I'm mostly concerned with the battery welds and the wiring, those are the weak points, even with all of the wiring contained within the enclosure, routed carefully to never cross over any other wires and with the welds checked using a FLIR during a pretty rapid discharge (twice as fast as the motor could ever do).
The OP has mounted the charge controller and the motor controller to a piece of wood (which will flex a bit but not much) which in turn appears to be protected in only one axis (side-to-side) and is either free to move or rigid in the other two. The wiring runs 'cold' without any kind of extra protection through the wood that it is mounted on. The frame is unsprung as far as I can tell, which especially for the front is not a luxury on a bike this heavy, which makes bike+battery the unsprung weight (I think I see a saddle pin with a rubber mount so there is some flex there). That battery box may have some foam in it or some other suspension for the battery which is good.
As long as he's on good asphalt this setup will work, but as soon as you go on less perfect roads I think that it will give trouble over time. DIY stuff like this looks great on the day you build it if you don't build it for abuse, but exposed wiring is dangerous and vibration as well as the weather are going to be rough on this. I'm curious what it will look like a year from now if used intensively, and also how the wire runs are on the other side of that board.
End result, everything is perfectly potted except the topside of an aluminium heatsink.
In their dreams maybe, that looks more like 40W sized poly panel, and it'll never get close to that unless they're driving it along the equator with active cooling on the other side.
So getting +50% charge in a day is not too bad.
I mean except for the 2nd passenger with rowing & leg press interface, that's......forward thinking!
Instead, the Lightyear One has focused on streamlining the solar panels in an aerodynamic way that doesn't take advantage of extra power when parked.
Feels like vandalism or just accidental collisions would be real problems
Bike also doesn't have suspension. You will feel everything with all that weight.
Never put weight on the front wheel inhibiting fast turns and reaction time.
Electric Tut-Tut with pedals might be more practical if ever allowed in bike lanes
https://electrek.co/2023/02/02/i-bought-electric-rickshaw-tu...
You could put more panels on the sides. I wonder if there's a two sided panel that could take sunlight from either side, you could have it on one side only and get the light through the wheel and spokes from the other side depending how it's facing.
The better solution is to lug around a charger, and failing that to simply carry around another battery to extend your range.
But the immediate problem is that extra E-Bike batteries are very expensive. Each OEM has their own little monopoly with their own chargers and customized plugs, and charges through the nose for replacements.
My E-bike uses a Bosch, and e.g. [1] has replacement cells for it that retail at 1/3 or even 1/4 of the full battery pack of the same capacity. The casing, charge controller etc. should add some cost, but not that much.
I think a much more practical solution is to work on bridging that gap, another commentator commented out that USB PD is stepping up to the 48v range from 20v.
But E-Bike batteries are so expensive that even if you had to carry everything with you to up-voltage portable batteries to 220v, carry the OEM charger, and then plug it into a portable standard outlet you might still come way ahead v.s. buying another OEM battery.
You'd need to stop to charge, but that's usually not an issues on longer trips.
It's insane that this is even a viable option, but that's how overpriced these batteries are.
In this case, I would assume the upgraded controller is able to drive a higher voltage in order to attained the increased current. The smaller controller likely has smaller, cheaper power transistors and related components, so it must limit itself to the maximum current (and power and heat) those transistors can handle.
BTW, the resistance of motors these days is relatively low... They can likely not handle the full amperage from the battery for very long. They simply must use controllers to switch the current.
The reason I ask is, I'm working on an ebike that had a cheap undersized controller installed such that if I drive it at full throttle long enough, the controller overheats and shuts off. My plan was to simply upgrade to a controller with a much higher amperage rating, removing that as a concern.
But it sounds like doing this could just burn out the motor? I think I can change the software of the controller to limit maximum power output, I'll have to do that I guess.
I would not have expected a controller capable of 60A to attempt to actually force 60A through a 48V, 1000W motor if the throttle was held down; I would have expected it to apply battery-level voltage to the motor (or do an internal step up/down to a constant 48V) and simply permit the motor to draw whatever amperage it pleased at that in-spec voltage.
But if you compare it to a reasonably light "ordinary" bike, driven by muscle power, this is nowhere near "eco". It's heavy, it's expensive, and it's not going to do much good for your health. If you want a vehicle with an engine, leave the pedals out and be honest about it. Otherwise, a classical bicycle is the better fit in many ways.
> It's expensive
It's cheap. An e-bike like this costs as much as some of the extras on a car.
> it's not going to do much good for your health
This is just incorrect - if you have an e-bike, you are way more likely to use it compared to a muscle powered bike, and you are going to ride longer distances with it. In sum, the positive health effects of using an e-bike regularily are larger than using a muscle-powered one.
> compare it to a reasonably light "ordinary" bike, driven by muscle power, this is nowhere near "eco"
if you count calories, and are on an average omnivore diet, e-bikes are actually more efficient than muscle-powered bikes. it's eco.
> leave the pedals out and be honest about it
?? not sure what you mean with honest?
> in a few years when it's out of fashion
opinion: e-bikes are not a fashion, but here to stay. it's far less trash than a car.
The gasoline-electro argument is kind of true for cars though, electric cars are not eco, just slightly better than gas cars.
That might be true for someone, but it's a bit of a leap in general
So I'd say the presence of e-bike is a positive for the overall health of the society compared to these people owning a car. On a 1:1 case of having the choice to ride a muscular powered bike vs ebike this is different.
What prevents people from biking is mostly weather: cold/hot, rain. Neither are fixed by an ebike.
When it's chilly, an ebike is actually worse. You heat up less and go faster, so more windchill.
Yes, if you buy a car new, and you are lucky enough to have the money and location (which is also money) to choose to buy this instead of buying a car with that extra.
In other words: it's not cheap for most people, who need a car or two anyway, and buy a second hand one.
Imagine you are in the normal situation of having two parents, both driving to their jobs, and dropping one or two children to school or other activities.
If you can replace one of your cars with an e-bike, you:
- at least one of you is white collar and can work from home or have flexible hours
- live somewhere that transportation is simple for at least half of your journeys, and that half of your driving journeys can all be done by the same person
- have only one full-time worker, who has a big enough salary to cover all needs
- live in an expensive metropolis with excellent public transport
Now, my family has only one car, but we tick three of those boxes and live in a cycling-friendly city. I would never pretend that what we do is particularly doable by a large number of people.
I agree that there more of what you list you check, the better a bike is, but I think most people could check enough of those boxes if their tried just a little. It would be worth it for them for health reasons.
As my list indicates, anyone who has this has an easier time of it, but they quite possibly paid more for their house if they live near their employer.\
> Most people are in a long term marriage like relationship
Are they? Why does this matter?
> I think most people could check enough of those boxes if their tried just a little
Most of them need relatively little effort if they have a tech job - that's my situation. They get far, far more difficult if they have a blue collar / low paying job / kids with issues / health issues of their own.
I said "marriage like" relationship. Marriage as other legal and cultural connotations that may not apply, but your relationship is still such that you can share one car.
My parents still have their bicycles which they bought 48 years ago and use them daily. Minor repairs over the years, but by and large the same vehicles. I want to see you use your ebike essentially unchanged 48 years from now. With the original battery obviously, and with its bluetooth controlled smartphone app. Good luck.
Where I live, the people who bought an ebike and use it daily/regularly are disproportionally people who were already using an ordinary bicycle regularly. (A local newspaper made a study in collaboration with the local university.) The thought that it transitions people from using cars to something more green and healthy is largely a myth. It transitioned people from burning 600 kcal on their commute to 100 kcal on their commute. And when it's raining they still use their car.
1) The user doesn't want to be sweaty at the destination e.g. work, dinner
2) The user doesn't want to be too tired at the destination e.g. park, gym
3) the destination is too far away for their level of fitness
4) the destination takes too long to get to (a fit person can go much faster on an e-bike)
(3) and (4) are especially important in the US where bicyclists have to contend with the distances created by car-centric design.
[1] https://electrek.co/2019/08/11/electric-bike-riders-more-exe...
I semi recently moved from small town Canada to big city Europe and decided to go car free and just use an electric scooter. If I could plug it in (and not have to lug around a charger) and lock it up somewhere, that would be amazing. I get about 15k-20km per charge, which is more or less perfect since I can go anywhere in the city and back home, but it would be nice to top up on some occasions.
I wonder if there's progress on thin film PV, so that you could have flexible bike solar body.