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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)

#31

Post by msla »

Gibbon1 wrote: post #18
chihuahua wrote: post #15

Earlier quoted context omitted.

To be fair (as a joke), it's from Low Tech Magazine. Lithium batteries are too high-tech for them. They want you to power your mechanical blender, mixer, and other machines with a drive belt. Turn the drum of your washing machine with a wood fire heating the water.

Solar panels I think are too high tech for them. I remember reading about low tech efficient cook stoves for poor countries and thinking the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

> the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

Those would definitely be hits.

Also, solar panels are old. Bell Labs demonstrated the first practical silicon solar cell in 1954. At some point, you're just trying to split (possibly nonexistent) hairs for an aesthetic, as opposed to making a principled stand against technology.

https://www.aps.org/apsnews/2009/04/bell-labs-silicon-solar-...

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

#32

Post by wolfi1 »

rgmerk wrote: post #13
usrusr wrote: post #4

Needs "2011" in the title. For example the section about friction drive hasn't been true for about a decade now

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

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

#33

Post by stephen_g »

pocksuppet wrote: post #29
KennyBlanken wrote: post #25

Earlier quoted context omitted.

[flagged]

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 Ownership (TCO) basis, it was already cheaper quite a while ago (for the last 5 years I'd guess). It was a combination of LiFePO4 batteries having such longer cycle lives than any lead-acid chemistry, and the greater depth of discharge meaning you could use a lot more of the energy. So if you build a new lead-acid based system, you'd need almost double the amp-hours of batteries to supply the same amount of energy with a safe depth of discharge, and you'd still have to replace them much sooner. So you'd not only have to factor buying a lot more batteries with lead acid but also replacing all the lead acid batteries at least once while a LiFePO4 system would continue to operate.

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

#34

Post by rgmerk »

Gibbon1 wrote: post #18
chihuahua wrote: post #15

Earlier quoted context omitted.

To be fair (as a joke), it's from Low Tech Magazine. Lithium batteries are too high-tech for them. They want you to power your mechanical blender, mixer, and other machines with a drive belt. Turn the drum of your washing machine with a wood fire heating the water.

Solar panels I think are too high tech for them. I remember reading about low tech efficient cook stoves for poor countries and thinking the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

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.

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

#35

Post by eru »

rgmerk wrote: post #34
Gibbon1 wrote: post #18

Earlier quoted context omitted.

Solar panels I think are too high tech for them. I remember reading about low tech efficient cook stoves for poor countries and thinking the misses would rather have an induction burner, microwave, and an ice chest running off a solar panel.

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.

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

#36

Post by Walf »

tocs3 wrote: post #2

Some things I would like to see are pedal controlled devices. Something like a pedal controlled wheelchair, not powered by the pedals just control the forward and back motion. My mother with sever arthritis can still pedal but has a very hard time walking. It would be a little exercise doing something that needs to be done (getting around). A pedal controlled remote control lawnmower would be nifty also.

Have you seen what people are doing with hoverboards + wheelchairs? Carer- & user-operated variations. Not professional solutions, but certainly fill a need.

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

#37

Post by mmooss »

> An energy loss of 42 to 67.5 percent of naturally means that it takes 42 to 67.5 percent more effort or time to power a device (say, a blender) via electricity compared to powering the same device mechanically.

Nope. If input is 100W, loss is 60%, and resulting in output of 40W, then to increase output to 100W you don't need 60% more input (which would output 64W) you need 150% more input.

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

#38

Post by scotty79 »

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…

You can have a motor with planetary gearbox built in.

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

#40

Post by lostlogin »

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.

> dynohub

Thanks, I learned something. I’m suprised how little drag they seem to add.

https://www.cyclingabout.com/dynamo-hub-power-drag-testing-s...

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