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Commercially Available Bike Generators Are Not Sustainable (2011)

solar.lowtechmagazine.com

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Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#41

Post by [deleted] »

KennyBlanken wrote: post #28
scotty79 wrote: post #5

You could attach pedals directly to motor axle and control charging power drawn precisely to ensure smooth rotation in absence of the flywheel. It could be really small.

No, you can't. Most generators have to be spun at a thousand or several thousand RPMs to put out any sort of amount of power. Your average inexperienced person can pedal at maybe 80rpm comfortably, but probably considers even that to be "fast." A road cyclist with a year or so under their belt will do 100rpm if they put their mind to it and are positioned well biomechanically. Above that, to do it and be smooth and e…

[deleted]

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#42

Post by emj »

stephen_g wrote: post #33
pocksuppet wrote: post #29

Earlier quoted context omitted.

When did lead-acid stop being cheaper than any version of lithium?

Pretty recently, maybe in the last year or so?. It's pretty crazy to see it - CATL have started selling LiFePO4 cells as low as US$63/kWh while lead acid tends to cost more than US$100 per kWh! Obviously a finished battery + retail margin is going to cost more than those figures but we're coming to the point where it will just be cheaper than lead acid on an amp-hour to amp-hour basis. Of course, on a Total Cost of O…

Lead acid is cheaper because they are really easy to recycle so in a low tech env they are preferable.

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#43

Post by wumms »

erelong wrote: post #19

Might have changed their attitude since then as they posted in 2022 about a DIY guide on making a bike generator: https://solar.lowtechmagazine.com/2022/03/how-to-build-a-pra...

> Our dashboard also includes a 220V circuit. That makes it compatible with grid-powered devices (110V in the US, 240V in the UK).

Retro-look nit: all are outdated nominal voltages. The US is 120 V (since the 1960s), while the UK and EU are 230 V (since the mid-1990s).

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#44

Post by alex_young »

wolfi1 wrote: post #32
rgmerk wrote: post #13

Earlier quoted context omitted.

Not to mention they’re talking about lead-acid batteries, which have been replaced for pretty much every application, except (for now) starter motor batteries for combustion vehicles, by the various lithium batteries.

even EVs still have lead acid batteries, not all, but most

"have" is doing most of the work here. Most EVs have a small 12v battery to power 12v components. But the driving the car to the store part is done with lithium.

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#46

Post by mrob »

sunshinesnacks wrote: post #26
NewsaHackO wrote: post #22

Earlier quoted context omitted.

I thought he was posting about some retro product until I saw the USB ports in the energy delivery. Weird that he edited his photos to look like that, and used retro components otherwise.

I think the photos look like that to achieve a very small file size. The whole site is hosted and a small solar and battery powered server, so every MB matters.

For photographic images, dithered PNGs have worse quality:size ratio than JPEGs. If you want small files and are willing to sacrifice quality you can turn the JPEG compression up or reduce the resolution.

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#47

Post by Gibbon1 »

eru wrote: post #35
rgmerk wrote: post #34

Earlier quoted context omitted.

I would too...but an off-grid solar and battery setup sufficient to run the induction stove and microwave is still well into four figures - cheap for a developed country resident who wants some basic comforts in their wilderness lodge, but still well out of reach for a subsistence farmer in the poorest parts of the world.

Increasingly becoming more affordable. Especially as financing becomes easier. And you don't have to buy everything all at once.

That's the thing, like the used to be very expensive swing compressor ice chests that you can buy in the US for $150. You'd only need a 100 amp hour battery and a 100W solar panel to power it.

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#48

Post by ygra »

fergie wrote: post #39

I'm suprised that the author didn't consider dynohubs which were also a thing in back in 2011, and are getting slightly better all the time.

Are there options that don't limit the output power? Typically the light power is limited, so dynamos only provide around 5 W or so, which already makes them not so attractive even for charging your phone on a bike.

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#49

Post by thenthenthen »

physicalecon wrote: post #24
NewsaHackO wrote: post #22

Earlier quoted context omitted.

I thought he was posting about some retro product until I saw the USB ports in the energy delivery. Weird that he edited his photos to look like that, and used retro components otherwise.

The author does all sorts of odd-looking optimizations in order to make the web page run on a single host of cheap battery/solar powered compute. It does seem a bit extreme, but the proof of the pudding is in the eating: this website has been featured on the HN front page many times and I’ve not seen it ever falter. The same cannot be said for the many run of the mill “infinite scalability” cloud based SPA’s that mak…

It is an experiment, over the years various people have contributed “odd-looking” optimisations, its a great project!

Re: Commercially Available Bike Generators Are Not Sustainable (2011)

#50

Post by stephen_g »

emj wrote: post #42
stephen_g wrote: post #33

Earlier quoted context omitted.

Pretty recently, maybe in the last year or so?. It's pretty crazy to see it - CATL have started selling LiFePO4 cells as low as US$63/kWh while lead acid tends to cost more than US$100 per kWh! Obviously a finished battery + retail margin is going to cost more than those figures but we're coming to the point where it will just be cheaper than lead acid on an amp-hour to amp-hour basis. Of course, on a Total Cost of O…

Lead acid is cheaper because they are really easy to recycle so in a low tech env they are preferable.

I don’t know about that - yes it’s simpler to recycle but the cycle life is at least four times longer (I had accidentally understated in my post, did some more reading and lead acid is worse than I remembered), but apparently advanced LiFePO4 cells are getting potentially more like eight or nine times the cycle count!

So if you think about the amount of materials - lead acid are almost double the weight vs. lithium batteries per amp hour to start with, then multiply by two because of the usable capacity difference, times four to eight for the cycle life… So you’re talking having to recycle something like sixteen to thirty-two times the weight of the lithium batteries in lead, before the LiFePO4 batteries would have even reached their end of life!

It’s really almost unbelievable how much better and cheaper the lithium batteries have become!

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